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Journal of Clinical Oncology, Vol 24, No 15 (May 20), 2006: pp. 2359-2367 © 2006 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.03.2433 Immunohistochemical Test for MLH1 and MSH2 Expression Predicts Clinical Outcome in Stage II and III Colorectal Cancer Patients
From the Department of Experimental and Diagnostic Medicine, Section of Anatomic Pathology, University of Ferrara; and the Division of Clinical Oncology, St Anna Hospital, Ferrara, Italy Address reprint requests to Giovanni Lanza, MD, Dipartimento di Medicina Sperimentale e Diagnostica, Sezione di Anatomia Istologia e Citologia Patologica, Università di Ferrara, Via Fossato di Mortara 64/b, 44100 Ferrara, Italy; e-mail: lng{at}unife.it
Purpose To evaluate the prognostic significance of DNA mismatch repair (MMR) status in a large series of stage II and III colorectal cancer patients. The relationship among MMR status, adjuvant chemotherapy, and clinical outcome was also investigated. Patients and Methods The study included 718 patients with colorectal adenocarcinoma (393 stage II and 325 stage III) who underwent curative surgical resection. MMR status was determined by immunohistochemical analysis of MLH1 and MSH2 expression. Microsatellite instability (MSI) was assessed in 363 patients using mononucleotide and dinucleotide markers. Results One hundred fourteen (15.9%) carcinomas showed abnormal MMR protein (MMRP) expression (96 MLH1 negative and 18 MSH2 negative) and were classified as MMRP negative, whereas 604 tumors demonstrated normal MLH1/MSH2 immunoreactivity (MMRP positive). MLH1/MSH2 expression was closely related to MSI status (P < .001) and several clinicopathologic features. Patients with MMRP-negative carcinomas demonstrated a marked reduction in the risk of cancer-related death with respect to patients with MMRP-positive tumors (hazard ratio, 0.2579; 95% CI, 0.1289 to 0.5159). A better clinical outcome for patients with MMRP-negative tumors was observed in both stage II (P = .0006) and stage III (P = .0052) disease. In stage III disease, the survival advantage conferred by MMRP-negative tumors was more evident among patients treated with surgery alone than among patients who received adjuvant chemotherapy. A nonsignificant trend for survival benefit from adjuvant chemotherapy was observed among patients with MMRP-positive carcinomas but not among those with MMRP-negative carcinomas. Conclusion Immunohistochemical testing for MLH1/MSH2 expression provides useful prognostic information for the management of stage II and III colorectal cancer patients.
Despite great advances in our knowledge of the molecular basis of colorectal cancer, no molecular marker is actually used in the management of the disease. In particular, several genetic changes have been proposed as prognostic indicators, but none of them has been validated for clinical use.1,2 However, in recent years a growing body of evidence is accumulating that assessment of microsatellite instability (MSI) status provides useful prognostic information in this tumor type.3 MSI is characterized by the presence in tumor DNA of widespread alterations in the length of short repeated sequences called microsatellites. According to international convention,4 colorectal tumors are classified as high-frequency MSI (MSI-H) when instability occurs in at least 30% of the loci examined and as low-frequency MSI (MSI-L) when less than 30% of loci are unstable. Tumors not showing alterations in the length of the DNA sequences studied are classified as microsatellite stable (MSS). MSI-H is the hallmark of hereditary nonpolyposis colorectal cancer and occurs also in 10% to 15% of sporadic large bowel cancers.5-9 MSI-H colorectal adenocarcinomas develop through a genetic pathway different from that operating in MSS tumors10-12 and display distinctive pathologic features, such as proximal location, poor differentiation, mucinous and medullary phenotype, and marked peritumoral and intratumoral lymphocytic infiltration.13-17 In contrast, the clinicopathologic and the molecular characteristics of MSI-L large bowel tumors do not seem to be different from those of MSS carcinomas, although some specific alterations in MSI-L carcinomas have been described recently.18,19 Several investigations demonstrated that MSI-H colorectal carcinomas behave less aggressively than common large bowel tumors. The survival advantage conferred by the MSI-H phenotype was also shown to be independent of tumor stage and other clinical and pathologic variables in studies performed on large series of patients.16,17,20-27 However, in view of a possible clinical use, the prognostic significance of MSI status in stage II and stage III disease needs to be more precisely defined. In addition, recent evidence suggests that patients with microsatellite unstable colorectal cancers lack a survival benefit from fluorouracil-based adjuvant chemotherapy (FU-AC).3,28-30 Conflicting results have been reported previously with regard to this topic,31,32 and the role of MSI status as a predictive factor of benefit from FU-AC requires urgent additional evaluation. MSI-H is determined by defects in the DNA mismatch repair (MMR) system in the large majority of tumors by inactivation of the MLH1 and MSH2 genes.6,8 In hereditary nonpolyposis colorectal cancer, MSI-H is produced by germline mutations of one of the MMR genes with somatic inactivation of the remaining wild-type allele.8,9 In sporadic tumors, epigenetic silencing of the MLH1 gene by promoter methylation is the major mechanism leading to MMR deficiency and MSI-H.33-35 Genetic or epigenetic inactivation of the MLH1 and MSH2 genes is associated frequently with loss of expression of the corresponding protein, and recent investigations demonstrated that immunohistochemical analysis of MLH1 and MSH2 expression specifically identifies MSI-H colorectal carcinomas.17,36-46 Only a small fraction of MMR-defective tumors, caused by mutations in the MLH1 gene not associated with the loss of MLH1 immunoreactivity or caused by mutations in the MSH6 and PMS2 genes, are not recognized in this way. Therefore, an immunohistochemical test for MLH1 and MSH2 expression represents a rapid, cost-effective, and reliable method for the detection of the large majority of MMR-defective colorectal tumors. In this study, we evaluated the prognostic significance of MMR status as determined by genetic and immunohistochemical analyses in a large cohort of stage II and stage III colorectal cancer patients. In stage III disease, the relationship among adjuvant chemotherapy, MMR status, and clinical outcome was also investigated.
The study included 802 consecutive patients with TNM47 stage II (n = 441) or stage III (n = 361) colorectal adenocarcinoma who underwent curative surgical resection between January 1986 and December 1995 at the St Anna Hospital (Ferrara, Italy). Patients older than 85 years and those with multiple synchronous large bowel carcinomas, idiopathic inflammatory bowel disease, or familial adenomatous polyposis were excluded. Patients who received preoperative radiation therapy and those with a malignant tumor detected within the previous 5 years were also excluded. Of the 802 patients, 41 (20 with stage II and 21 with stage III disease) died postoperatively and 13 (eight stage II and five stage III) were lost to follow-up. An additional 20 patients (14 stage II and six stage III) were excluded because tumor blocks for immunohistochemical analysis were not available. Finally, 10 (1.4%) of the 728 patients examined were excluded from the study because the quality of immunostaining was considered unsatisfactory. The mean age of the remaining 718 patients (393 stage II and 325 stage III; 359 men and 359 women) was 65.0 years (median, 66 years; range, 27 to 85 years). One hundred eighty tumors were located in the right colon (cecum and ascending colon), 102 tumors were located in the transverse colon (including both flexures), 59 tumors were located in the descending colon, 207 tumors were located in the sigmoid colon, and 170 tumors were located in the rectum (comprising the rectosigmoid junction). In most analyses, tumors were subdivided in two anatomic subgroups: carcinomas of the proximal colon (right and transverse colon) and carcinomas of the distal colon (localized distally to the splenic flexure). The majority of patients were observed at the St Anna Hospital's Division of Clinical Oncology according to a standardized protocol. For the remaining patients, information regarding clinical outcome was obtained from hospital chart review and/or direct telephone interview with the patients' personal physicians. Sixty-five of the 312 patients with stage II colon cancer and 89 of the 236 patients with stage III colon cancer received postoperative FU-AC. Of the 81 patients with stage II rectal cancer, 20 received postoperative radiation therapy and six received postoperative radiation plus chemotherapy. Of the 89 patients with stage III rectal cancer, 17 received postoperative radiation therapy and 33 received postoperative radiation plus chemotherapy. Overall, 71 (18.1%) of the 393 patients with stage II disease and 122 (37.5%) of the 325 patients with stage III disease have been treated with FU-AC. Most patients received a regimen of FU 370 to 400 mg/m2 plus folinic acid (pure L-form) 100 mg/m2 daily for 5 days, every 28 days for six cycles.48 Fifty-eight patients with colon cancer (28 stage II and 30 stage III) were included in a randomized multicenter clinical trial of adjuvant chemotherapy.49 The mean follow-up in surviving patients was 93.9 months (median, 90.5 months; range, 63 to 144 months).
Histopathologic Evaluation
Immunohistochemical Analysis Tumors showing complete loss of nuclear MLH1 or MSH2 expression were classified as MLH1 negative or MSH2 negative. Nuclear immunostaining of normal epithelial cells, lymphocytes, and stromal cells served as internal positive controls in each case. Carcinomas with normal expression of MLH1 and MSH2 gene products (ie, presence of nuclear immunostaining in a large proportion of neoplastic cells) were classified as MLH1 positive and MSH2 positive. All tumors were evaluated independently by two pathologists (G.L. and R.G.) without knowledge of clinical data and MSI status. Immunohistochemical analysis of p53 protein expression was performed as reported in previous studies.16,51 Tumors showing a proportion of stained nuclei higher than 10% were classified as p53 positive.
Microsatellite Analysis In all the 363 patient samples analyzed, six microsatellite loci (BAT26, BAT40, D18S58, D18S61, D17S855, and D17S786) were examined using a fluorescence-based polymerase chain reaction (PCR) method, as reported previously.16,41 In addition, in the majority of samples, several of the following microsatellite loci have also been evaluated: BAT25, D2S123, D5S346, D17S250, D18S65, D18S69, D17S796, D17S1176, D8S261, D8S254, and D8S550. PCR products were run in an ABI PRISM 377 DNA sequencer (Perkin-Elmer Applied Biosystems Division, Foster City, CA) and analyzed by the GeneScan 3.1 version software (Perkin-Elmer).
MSI was defined as presence in the tumor DNA of PCR products of abnormal size with respect to the DNA of corresponding normal tissue. According to the guidelines of the International Workshop of Bethesda,4 tumors showing instability at
DNA Ploidy Analysis
Statistical Analysis
MLH1/MSH2 Expression, MSI Status, and Clinicopathologic Features Of the 718 colorectal adenocarcinomas examined, 604 (84.1%) showed normal nuclear expression of both MLH1 and MSH2 proteins (MLH1/MSH2 positive), 96 (13.4%) showed complete loss of MLH1 expression with normal MSH2 immunoreactivity (MLH1 negative), and 18 (2.5%) demonstrated complete loss of MSH2 expression with normal MLH1 immunoreactivity (MSH2 negative). In all of the analyses, tumors with abnormal MMR protein expression (MLH1 negative and MSH2 negative, 15.9% of samples) were grouped together and indicated as MMR protein (MMRP) negative, whereas MLH1/MSH2-positive carcinomas were indicated as MMRP positive. Microsatellite analysis was performed in 363 carcinomas (192 stage II and 171 stage III). According to international convention,4 271 tumors were classified as MSS (74.7%), 17 were classified as MSI-L (4.7%), and 75 (20.6%) were classified as MSI-H. All of the MSI-L and MSS carcinomas displayed normal MLH1 and MSH2 expression (MMRP positive). Of the 75 carcinomas classified as MSI-H by genetic analysis, 68 (90.7%) were MMRP negative (57 MLH1 negative and 11 MSH2 negative) and seven (9.3%) were MMRP positive (P < .001). Therefore, in this series, immunohistochemical analysis recognized more than 90% of MSI-H tumors, with a specificity of 100%. The relationship between clinicopathologic features and MLH1/MSH2 expression is listed in Table 1. MMRP-negative carcinomas occurred more frequently in women (P = .003) and among patients older than 70 years (P = .008) with respect to MMRP-positive tumors. In addition, MMRP-negative carcinomas were characterized by proximal location, poor differentiation, mucinous and medullary histology, and marked peritumoral Crohn's-like lymphoid reaction (all P < .001). MMRP-negative tumors were also more likely to be stage II than were MMRP-positive cancers (64% v 53%; P = .031). Finally, the large majority of MMRP-negative carcinomas were p53 negative (88%) and DNA diploid (82.6%), whereas MMRP-positive tumors were prevalently p53 positive (60%; P < .001) and DNA aneuploid (82.1%; P < .001). Similar results were obtained when the clinicopathologic features of MSI-H and MSI-L/MSS carcinomas were compared (data not shown).
Survival Analyses Patients with stage III tumors demonstrated reduced disease-specific survival with respect to patients with stage II tumors (Fig 1A; P < .0001). One hundred fifty-one (46.5%) of the 325 patients with stage III carcinomas developed distant metastases and/or local recurrence and 142 (43.7%) died as a result of the disease. In contrast, only 72 (18.3%) of the 393 patients with stage II carcinomas developed distant metastases and/or local recurrence and 66 (16.8%) died as a result of the disease (Table 2).
Patients with MMRP-negative tumors showed a better clinical outcome than patients with MMRP-positive carcinomas (Fig 1B; P < .0001). Respectively, 10 (8.8%) of the 114 patients with MMRP-negative tumors and 198 (32.8%) of the 604 patients with MMRP-positive cancers died as a result of the disease during the observation period (Table 2). Furthermore, when patients were stratified by TNM stage, the survival advantage for patients with MMRP-negative tumors was clearly evident and statistically significant in both stage II and stage III disease (Figs 1C and 1D; P = .0006 and P = .0052, respectively). In detail, the 6-year survival rates for patients with stage II MMRP-negative, stage II MMRP-positive, stage III MMRP-negative, and stage III MMRP-positive carcinomas were 97%, 82%, 78%, and 56%, respectively. The survival advantage for patients with MMRP-negative tumors in both stage II and stage III disease was also evident when only tumors of the colon (stage II, P = .0016; stage III, P = .0224) or only tumors of the proximal colon (stage II, P = .0043; stage III, P = .0121) were examined. Among the 363 patients whose tumors have been investigated by genetic analysis, MSI status was significantly related to disease-specific survival. Patients with MSI-H carcinomas showed a better clinical outcome than patients with MSI-L/MSS tumors in all cases (P = .0002; Table 2), as well as in stage II and stage III disease analyzed separately (P = .0059 and P = .0375, respectively; data not shown). In the group of 203 stage III patients who did not receive FU-AC, patients with MMRP-negative tumors demonstrated a much better clinical outcome than those with MMRP-positive carcinomas (Fig 2A; P = .0054). The 6-year survival rates were 79% and 52%, respectively. A nonsignificant trend for better survival of patients with MMRP-negative tumors was observed among the 122 stage III patients treated with FU-AC (Fig 2B; P = .3177). However, in this analysis only a small number of patients with MMRP-negative carcinomas was included (n = 9). A trend for a survival benefit from adjuvant chemotherapy was observed among the 284 stage III patients with MMRP-positive tumors, but the difference was not statistically significant (P = .0776; Fig 3A). Conversely, among the 41 patients with stage III MMRP-negative carcinomas, no difference in the duration of survival was observed between patients who received adjuvant chemotherapy and those who did not (P = .9100; Fig 3B).
In addition to tumor stage and MLH1/MSH2 expression, other clinical and pathologic variables were related significantly to disease-specific survival among the 718 patients included in the study (Table 2). A multivariate analysis according to the Cox proportional hazards model was performed in the whole series of patients including MLH1/MSH2 expression, age at surgery, sex, tumor site, TNM stage, tumor type, grade of differentiation, lymphocytic infiltration at the tumor margin, vein invasion, and FU-AC as covariates (model 1). Patients with MMRP-negative carcinomas demonstrated a marked reduction in the risk of cancer-related death with respect to patients whose tumors showed normal MLH1/MSH2 expression (hazard ratio [HR], 0.2579; 95% CI, 0.1289 to 0.5159; P = .0001; Table 3). Similar results were obtained when patients with rectal cancer were excluded from the analysis (HR, 0.2297; 95% CI, 0.1118 to 0.4719; P = .0001; data not shown).
A multivariate analysis was also performed in the group of 363 patients whose tumors have been evaluated by microsatellite genotyping. In this analysis (model 2), MSI status was included as covariate (MSI-H v MSI-L/MSS), whereas MLH1/MSH2 expression was excluded. In model 2, TNM stage, sex, MSI status, age at surgery, lymphocytic infiltration at the tumor margin, and extramural vein invasion were selected as significant independent predictors of disease-specific survival. Patients with MSI-H tumors exhibited a lower risk of cancer-related death than patients with non–MSI-H carcinomas (HR, 0.3167; 95% CI, 0.1528 to 0.6566; P = .002; Table 3).
The large majority of previous studies evaluating the prognostic or predictive value of MMR status in colorectal cancer have been performed using microsatellite analysis to assess tumor phenotype. However, genetic analysis of MSI status is time consuming and expensive, and needs specialized equipment. Recently, it has been demonstrated that immunohistochemical analysis of MLH1 and MSH2 expression is a rapid, cost-effective, and accurate method for the assessment of MMR status in colorectal adenocarcinomas.17,36-46 In this investigation, we used immunohistochemical analysis of MLH1/MSH2 expression to evaluate the prognostic significance of MMR status in a large series of stage II and stage III colorectal cancer patients. In our study, patients whose tumors demonstrated loss of MMR protein expression (MMRP negative) had a better clinical outcome than patients with MMRP-positive tumors in stage II as well as in stage III disease. Moreover, in multivariate analysis, the survival advantage for patients with MMRP-negative carcinomas was independent from several clinical and pathologic parameters. Specifically, patients with stage II MMRP-negative tumors showed an excellent clinical outcome (6-year survival rate, 97%). It is disputed whether patients with stage II colon cancer need to be treated with adjuvant chemotherapy.55,56 According to our data, stage II patients with MMRP-negative tumors (18.6% of all stage II patients and 43.2% of stage II patients with tumors localized in the proximal colon) should not require any additional treatment after surgical resection. Patients with MMRP-negative tumors demonstrated a better clinical outcome also in stage III disease. It is important to note that in stage III disease the survival advantage conferred by MMRP-negative carcinomas was clearly evident among patients who did not receive FU-AC (6-year survival rates of 79% and 52% for patients with MMRP-negative and MMRP-positive tumors, respectively). A better survival for patients with MMRP-negative tumors was also observed among stage III patients who received adjuvant chemotherapy, but the difference failed to reach statistical significance. Furthermore, a nonsignificant trend for survival benefit from adjuvant chemotherapy was observed among stage III patients with MMRP-positive tumors, but not among stage III patients with MMRP-negative carcinomas. This last finding should be interpreted with caution, given that only 41 patients with MMRP-negative carcinomas were included in the analysis. In contrast with early studies,31,32 recent investigations indicate that colorectal cancer patients with MSI-H tumors do not benefit from FU-AC. Specifically, in a study performed on 570 patients with stage II and III colon cancer who were enrolled onto prospective randomized clinical trials of FU-AC, Ribic et al29 demonstrated a survival advantage for MSI-H tumors among patients who did not receive adjuvant chemotherapy, but not among patients who received the treatment. Furthermore, a significant beneficial effect of adjuvant chemotherapy on overall survival rate was observed in the group of patients with MSI-L/MSS tumors, whereas among patients with MSI-H carcinomas a trend toward worse clinical outcome for those receiving FU treatment was detected. Likewise, in a series of 204 stage II and III colorectal adenocarcinomas, Carethers et al30 showed a survival advantage for patients receiving FU-AC among those with non–MSI-H tumors but not among those with MSI-H carcinomas. These findings are in accordance with in vitro studies showing that MMR-deficient colon cancer cell lines are less responsive than MMR-proficient cell lines to FU as well as other chemotherapeutic agents.57-63 Additional investigations are needed to determine the value of MMR status as a predictor of survival benefit from FU-AC, especially in stage III colon cancer.3 Notwithstanding, our data provide strong evidence that MMR status is a powerful prognostic indicator in stage III patients treated by surgery alone, and that two groups of patients with different clinical outcome are distinguished on the basis of this molecular parameter. Adjuvant chemotherapy is considered the standard of care for patients with stage III colorectal cancer. However, the clinical course of stage III disease is heterogeneous, and approximately 50% of patients are cured by surgery alone. In our study, stage III patients with MMRP-negative tumors not receiving adjuvant chemotherapy displayed a cancer-specific survival similar to that of patients with stage II disease. If our findings are confirmed in other investigations, the advisability to treat this group of patients with adjuvant chemotherapy should be carefully evaluated, especially if additional markers to select stage III MSI-H tumors with favorable clinical outcome will be available.64-66 In agreement with previous studies, we found an excellent correlation between the results obtained by immunohistochemical and genetic analysis in the classification of colorectal tumors according to MMR status. In fact, all of the 288 carcinomas classified as MSS or MSI-L by microsatellite analysis showed normal MLH1/MSH2 expression by immunohistochemistry. Conversely, 68 (90.7%) of the 75 MSI-H carcinomas demonstrated complete loss of MLH1 or MSH2 protein expression. In our study, seven tumors were classified as MSI-H by genetic analysis but showed normal MLH1/MSH2 expression. We performed immunohistochemical analysis of the expression of two other MMR proteins (MSH6 and PMS2) in these seven MSI-H MMRP-positive carcinomas. Four tumors displayed complete loss of MSH6 expression and normal reactivity for PMS2 and one tumor demonstrated complete loss of PMS2 expression (with normal nuclear expression of the MSH6 protein), whereas the remaining two carcinomas were MSH6 and PMS2 positive. Therefore, mutations of the MSH6 and PMS2 genes are probably involved in the development of four and one of these cancers, respectively. The two MSI-H adenocarcinomas with normal expression of all of the four MMR proteins tested are most likely generated by mutations in the MLH1 gene that inactivate the MMR activity, but do not lead to loss of MLH1 immunoreactivity.46 In this investigation, MLH1/MSH2 immunoreactivity was demonstrated to be closely related to several pathologic features, such as tumor site, tumor type, grade of differentiation, nodal status, Crohn's-like lymphoid reaction, and also to DNA ploidy pattern and p53 protein expression. These data confirm and extend other investigations in which microsatellite or immunohistochemical analysis was employed to determine the MMR status of the tumors.13,14,16,25,27,41,67-70 The prognostic significance of MLH1/MSH2 expression in large bowel cancer has been evaluated previously only in a limited number of studies performed on small series of patients.38,71-74 Here, we demonstrated that immunohistochemical analysis of MLH1/MSH2 expression is suitable for large-scale clinical investigations and provides useful prognostic information for the management of stage II and III colorectal cancer patients. In conclusion, the results of this study indicate clearly that MMR status is a powerful prognostic indicator in colorectal cancer. In a near future, immunohistochemical analysis of MLH1/MSH2 expression could be introduced as a routine diagnostic test in the pathologic assessment of large bowel tumor specimens.
The authors indicated no potential conflicts of interest.
We thank Fernanda Mora and Daniela Nardo for excellent technical assistance.
Supported by the Consiglio Nazionale delle Ricerche, "Progetto Strategico Oncologia," Grant No. CU03.00366, and by the Ministero dell'Istruzione, dell'Università e della Ricerca, and the Fondazione Cassa di Risparmio di Ferrara. Presented in part at the 3rd European Organization for Research and Treatment of Cancer–National Cancer Institute International Meeting on Cancer Molecular Markers, Brussels, Belgium, April 18-20, 2004. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
1. Compton C, Fenoglio-Preiser CM, Pettigrew N, et al: American Joint Committee on Cancer Prognostic Factors Consensus Conference: Colorectal Working Group. Cancer 88:1739-1757, 2000[CrossRef][Medline] 2. Houlston RS: What we could do now: Molecular pathology of colorectal cancer. Mol Pathol 54:206-214, 2001 3. Popat S, Hubner R, Houlston RS: Systematic review of microsatellite instability and colorectal cancer prognosis. J Clin Oncol 23:609-618, 2005 4. Boland CR, Thibodeau SN, Hamilton SR, et al: A National Cancer Institute workshop on microsatellite instability for cancer detection and familial predisposition: Development of international criteria for the determination of microsatellite instability in colorectal cancer. Cancer Res 58:5248-5257, 1998 5. Rodriguez-Bigas MA, Boland CR, Hamilton SR, et al: A National Cancer Institute workshop on hereditary nonpolyposis colorectal cancer syndrome: Meeting highlights and Bethesda guidelines. J Natl Cancer Inst 89:1758-1762, 1997 6. Wheeler JM, Bodmer WF, Mortensen NJ: DNA mismatch repair genes and colorectal cancer. Gut 47:148-153, 2000 7. Chung DC, Rustgi AK: The hereditary nonpolyposis colorectal cancer syndrome: Genetics and clinical implications. Ann Intern Med 138:560-570, 2003 8. Peltomäki P: Role of DNA mismatch repair defects in the pathogenesis of human cancer. J Clin Oncol 21:1174-1179, 2003 9. de la Chapelle A: Genetic predisposition to colorectal cancer. Nat Rev Cancer 4:769-780, 2004[CrossRef][Medline] 10. Kinzler KW, Vogelstein B: Lessons from hereditary colorectal cancer. Cell 87:159-170, 1996[CrossRef][Medline] 11. Chung DC: The genetic basis of colorectal cancer: Insights into critical pathways of tumorigenesis. Gastroenterology 119:854-865, 2000[CrossRef][Medline] 12. Haydon AM, Jass JR: Emerging pathways in colorectal-cancer development. Lancet Oncol 3:83-88, 2002[CrossRef][Medline] 13. Kim H, Jen J, Vogelstein B, et al: Clinical and pathological characteristics of sporadic colorectal carcinomas with DNA replication errors in microsatellite sequences. Am J Pathol 145:148-156, 1994[Abstract] 14. Jass JR, Do KA, Simms LA, et al: Morphology of sporadic colorectal cancer with DNA replication errors. Gut 42:673-679, 1998 15. Dolcetti R, Viel A, Doglioni C, et al: High prevalence of activated intraepithelial cytotoxic T lymphocytes and increased neoplastic cell apoptosis in colorectal carcinomas with microsatellite instability. Am J Pathol 154:1805-1813, 1999 16. Gafà R, Maestri I, Matteuzzi M, et al: Sporadic colorectal adenocarcinomas with high-frequency microsatellite instability: Pathobiologic features, hMLH1 and hMSH2 expression, and clinical outcome. Cancer 89:2025-2037, 2000[CrossRef][Medline] 17. Ward R, Meagher A, Tomlinson I, et al: Microsatellite instability and the clinicopathological features of sporadic colorectal cancer. Gut 48:821-829, 2001 18. Whitehall VLJ, Walsh MD, Young J, et al: Methylation of O-6-methylguanine DNA methyltransferase characterizes a subset of colorectal cancer with low-level DNA microsatellite instability. Cancer Res 61:827-830, 2001 19. Mori Y, Selaru FM, Sato F, et al: The impact of microsatellite instability on the molecular phenotype of colorectal tumors. Cancer Res 63:4577-4582, 2003 20. Thibodeau SN, Bren G, Schaid D: Microsatellite instability in cancer of the proximal colon. Science 260:816-819, 1993 21. Bubb VJ, Curtis LJ, Cunningham C, et al: Microsatellite instability and the role of hMSH2 in sporadic colorectal cancer. Oncogene 12:2641-2649, 1996[Medline] 22. Halling KC, French AJ, McDonnell SK, et al: Microsatellite instability and 8p allelic imbalance in stage B2 and C colorectal cancers. J Natl Cancer Inst 91:1295-1303, 1999 23. Gryfe R, Kim H, Hsieh ETK, et al: Tumor microsatellite instability and clinical outcome in young patients with colorectal cancer. N Engl J Med 342:69-77, 2000 24. Wright CM, Dent OF, Barker M, et al: Prognostic significance of extensive microsatellite instability in sporadic clinicopathological stage C colorectal cancer. Br J Surg 87:1197-1202, 2000[CrossRef][Medline] 25. Samowitz WS, Curtin K, Ma KN, et al: Microsatellite instability in sporadic colon cancer is associated with an improved prognosis at the population level. Cancer Epidemiol Biomarkers Prev 10:917-923, 2001 26. Choi SW, Lee KJ, Bae YA, et al: Genetic classification of colorectal cancer based on chromosomal loss and microsatellite instability predicts survival. Clin Cancer Res 8:2311-2322, 2002 27. Diep CB, Thorstensen L, Meling GI, et al: Genetic tumor markers with prognostic impact in Dukes' stages B and C colorectal cancer patients. J Clin Oncol 21:820-829, 2003 28. Barratt PL, Seymour MT, Stenning SP, et al: DNA markers predicting benefit from adjuvant fluorouracil in patients with colon cancer: A molecular study. Lancet 360:1381-1391, 2002[CrossRef][Medline] 29. Ribic CM, Sargent DJ, Moore MJ, et al: Tumor microsatellite-instability status as a predictor of benefit from fluorouracil-based adjuvant chemotherapy for colon cancer. N Engl J Med 349:247-257, 2003 30. Carethers JM, Smith EJ, Behling CA, et al: Use of 5-Fluorouracil and survival in patients with microsatellite-unstable colorectal cancer. Gastroenterology 126:394-401, 2004[CrossRef][Medline] 31. Elsaleh H, Joseph D, Grieu F, et al: Association of tumour site and sex with survival benefit from adjuvant chemotherapy in colorectal cancer. Lancet 355:1745-1750, 2000[CrossRef][Medline] 32. Hemminki A, Mecklin JP, Järvinen H, et al: Microsatellite instability is a favorable prognostic indicator in patients with colorectal cancer receiving chemotherapy. Gastroenterology 119:921-928, 2000[CrossRef][Medline] 33. Cunningham JM, Christensen ER, Tester DJ, et al: Hypermethylation of the hMLH1 promoter in colon cancer with microsatellite instability. Cancer Res 58:3455-3460, 1998 34. Herman JG, Umar A, Polyak K, et al: Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma. Proc Natl Acad Sci U S A 95:6870-6875, 1998 35. Kuismanen SA, Holmberg MT, Salovaara R, et al: Genetic and epigenetic modification of MLH1 accounts for a major share of microsatellite-unstable colorectal cancers. Am J Pathol 156:1773-1779, 2000 36. Dietmaier W, Wallinger S, Bocker T, et al: Diagnostic microsatellite instability: Definition and correlation with mismatch repair protein expression. Cancer Res 57:4749-4756, 1997 37. Thibodeau SN, French AJ, Cunningham JM, et al: Microsatellite instability in colorectal cancer: Different mutator phenotypes and the principal involvement of hMLH1. Cancer Res 58:1713-1718, 1998 38. Cawkwell L, Gray S, Murgatroyd H, et al: Choice of management strategy for colorectal cancer based on a diagnostic immunohistochemical test for defective mismatch repair. Gut 45:409-415, 1999 39. Marcus VA, Madlensky L, Gryfe R, et al: Immunohistochemistry for hMLH1 and hMSH2: A practical test for DNA mismatch repair-deficient tumors. Am J Surg Pathol 23:1248-1255, 1999[CrossRef][Medline] 40. de la Chapelle A: Microsatellite instability phenotype of tumors: Genotyping or immunohistochemistry? The jury is still out. J Clin Oncol 20:897-899, 2002 41. Lanza G, Gafà R, Maestri I, et al: Immunohistochemical pattern of MLH1/MSH2 expression is related to clinical and pathological features in colorectal adenocarcinomas with microsatellite instability. Mod Pathol 15:741-749, 2002[CrossRef][Medline] 42. Lindor NM, Burgart LJ, Leontovich O, et al: Immunohistochemistry versus microsatellite instability testing in phenotyping colorectal tumors. J Clin Oncol 20:1043-1048, 2002 43. Ruszkiewicz A, Bennett G, Moore J, et al: Correlation of mismatch repair genes immunohistochemistry and microsatellite instability status in HNPCC-associated tumours. Pathology 34:541-547, 2002[Medline] 44. Hendriks Y, Franken P, Dierssen JW, et al: Conventional and tissue microarray immunohistochemical expression analysis of mismatch repair in hereditary colorectal tumors. Am J Pathol 162:469-477, 2003 45. Rigau V, Sebbagh N, Olschwang S, et al: Microsatellite instability in colorectal carcinoma. The comparison of immunohistochemistry and molecular biology suggests a role for hMSH6 immunostaining. Arch Pathol Lab Med 127:694-700, 2003[Medline] 46. Shia J, Ellis NA, Klimstra DS: The utility of immunohistochemical detection of DNA mismatch repair gene proteins. Virchows Arch 445:431-441, 2004[CrossRef][Medline] 47. Sobin LH, Wittekind C: UICC TNM Classification of Malignant Tumours (ed 5). New York, NY, John Wiley & Sons, 1997 48. International Multicentre Pooled Analysis of Colon Cancer Trials (IMPACT) Investigators: Efficacy of adjuvant fluorouracil and folinic acid in colon cancer. Lancet 345:939-944, 1995[CrossRef][Medline] 49. Di Costanzo F, Sobrero A, Gasperoni S, et al: Adjuvant chemotherapy in the treatment of colon cancer: Randomized multicenter trial of the Italian National Intergroup of Adjuvant Chemotherapy in Colon Cancer (INTACC). Ann Oncol 14:1365-1372, 2003 50. Jass JR, Sobin LH: World Health Organization. International Histological Classification of Tumours. Histological Typing of Intestinal Tumours (ed 2). Berlin, Germany, Springer-Verlag, 1989 51. Lanza G, Gafà R, Matteuzzi M, et al: Medullary-type poorly differentiated adenocarcinoma of the large bowel: A distinct clinicopathologic entity characterized by microsatellite instability and improved survival. J Clin Oncol 17:2429-2438, 1999 52. Jass JR, Atkin WS, Cuzick J, et al: The grading of rectal cancer: Historical perspectives and a multivariate analysis of 447 cases. Histopathology 10:437-459, 1986[Medline] 53. Graham DM, Appelman HD: Crohn's-like lymphoid reaction and colorectal carcinoma: A potential histologic prognosticator. Mod Pathol 3:332-335, 1990[Medline] 54. Lanza G, Gafà R, Santini A, et al: Prognostic significance of DNA ploidy in patients with stage II and stage III colon carcinoma: A prospective flow cytometric study. Cancer 82:49-59, 1998[CrossRef][Medline] 55. Benson AB III, Schrag D, Somerfield MR, et al: American Society of Clinical Oncology recommendations on adjuvant chemotherapy for stage II colon cancer. J Clin Oncol 22:3408-3419, 2004 56. Zaniboni A, Labianca R: Adjuvant therapy for stage II colon cancer: An elephant in the living room? Ann Oncol 15:1310-1318, 2004 57. Hawn MT, Umar A, Carethers JM, et al: Evidence for a connection between the mismatch repair system and the G2 cell cycle checkpoint. Cancer Res 55:3721-3725, 1995 58. Carethers JM, Hawn MT, Chauhan DP, et al: Competency in mismatch repair prohibits clonal expansion of cancer cells treated with N-methyl-N'-nitro-N-nitrosoguanidine. J Clin Invest 98:199-206, 1996[Medline] 59. Fink D, Aebi S, Howell SB: The role of DNA mismatch repair in drug resistance. Clin Cancer Res 4:1-6, 1998[Abstract] 60. Carethers JM, Chauhan DP, Fink D, et al: Mismatch repair proficiency and in vitro response to 5-fluorouracil. Gastroenterology 117:123-131, 1999[CrossRef][Medline] 61. Meyers M, Wagner MW, Hwang HS, et al: Role of the hMLH1 DNA mismatch repair protein in fluoropyrimidine-mediated cell death and cell cycle responses. Cancer Res 61:5193-5201, 2001 62. Arnold CN, Goel A, Boland CR: Role of hMLH1 promoter hypermethylation in drug resistance to 5-fluorouracil in colorectal cancer cell lines. Int J Cancer 106:66-73, 2003[CrossRef][Medline] 63. Bignami M, Casorelli I, Karran P: Mismatch repair and response to DNA-damaging antitumour therapies. Eur J Cancer 39:2142-2149, 2003[CrossRef][Medline] 64. Guidoboni M, Gafà R, Viel A, et al: Microsatellite instability and high content of activated cytotoxic lymphocytes identify colon cancer patients with a favorable prognosis. Am J Pathol 159:297-304, 2001 65. Watanabe T, Wu TT, Catalano PJ, et al: Molecular predictors of survival after adjuvant chemotherapy for colon cancer. N Engl J Med 344:1196-1206, 2001 66. Prall F, Dührkop T, Weirich V, et al: Prognostic role of CD8+ tumor-infiltrating lymphocytes in stage III colorectal cancer with and without microsatellite instability. Hum Pathol 35:808-816, 2004[CrossRef][Medline] 67. Risio M, Reato G, di Celle PF, et al: Microsatellite instability is associated with the histological features of the tumor in nonfamilial colorectal cancer. Cancer Res 56:5470-5474, 1996 68. Messerini L, Vitelli F, De Vitis LR, et al: Microsatellite instability in sporadic mucinous colorectal carcinomas: Relationship to clinico-pathological variables. J Pathol 182:380-384, 1997[CrossRef][Medline] 69. Chapusot C, Martin L, Mungra N, et al: Sporadic colorectal cancers with defective mismatch repair display a number of specific morphological characteristics: Relationship between the expression of hMLH1 and hMSH2 proteins and clinicopathological features of 273 adenocarcinomas. Histopathology 43:40-47, 2003[CrossRef][Medline] 70. Wright CL, Stewart ID: Histopathology and mismatch repair status of 458 consecutive colorectal carcinomas. Am J Surg Pathol 27:1393-1406, 2003[CrossRef][Medline] 71. Perrin J, Gouvernet J, Parriaux D, et al: MSH2 and MLH1 immunodetection and the prognosis of colon cancer. Int J Oncol 19:891-895, 2001[Medline] 72. Kruschewski M, Noske A, Haier J, et al: Is reduced expression of mismatch repair genes MLH1 and MSH2 in patients with sporadic colorectal cancer related to their prognosis? Clin Exp Metastasis 19:71-77, 2002[CrossRef][Medline] 73. Parc Y, Gueroult S, Mourra N, et al: Prognostic significance of microsatellite instability determined by immunohistochemical staining of MSH2 and MLH1 in sporadic T3N0M0 colon cancer. Gut 53:371-375, 2004 74. Smyth EF, Sharma A, Sivarajasingham N, et al: Prognostic implications of hMLH1 and p53 immunohistochemical status in right-sided colon cancer. Dis Colon Rectum 47:2086-2091, 2004[CrossRef][Medline] Submitted June 23, 2005; accepted March 1, 2006.
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Copyright © 2006 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
30% of microsatellite loci were classified as MSI-H, tumors demonstrating instability at less than 30% of microsatellite loci were classified as MSI-L, and tumors without detectable MSI were classified as MSS. 
2 test or the Fisher's exact test, as appropriate. Survival curves were generated according to the method of Kaplan and Meier and compared by the log-rank test. Multivariate analyses were performed with the Cox proportional hazards model. Patients who died as a result of causes unrelated to colorectal cancer were censored at the time of death. The reported P values are two-sided and P values of less than .05 were considered to indicate statistical significance. All data were analyzed using the SPSS statistical software, Version 8.0 (SPSS Inc, Chicago, IL). 
