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Journal of Clinical Oncology, Vol 24, No 1 (January 1), 2006: pp. 123-128 © 2006 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.03.5964 Low Value of [18F]-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography in Primary Staging of Early-Stage Cervical Cancer Before Radical HysterectomyFrom the Departments of Obstetrics and Gynecology, Nuclear Medicine, Radiology, Pathology, and Radiation Oncology, Chang Gung Memorial Hospital; and Graduate Institutes of Basic Medical Sciences and Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan. Address reprint requests to Chyong-Huey Lai, MD, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital Linkou Medical Center, 5 Fu-Shin St, Kueishan, Taoyuan 333, Taiwan; e-mail: sh46erry{at}ms6.hinet.net
PURPOSE: The role of positron emission tomography (PET) with [18F]-fluoro-2-deoxy-D-glucose (FDG) in early-stage cervical cancer is unclear. We aimed to investigate the clinical benefit of FDG-PET in primary staging before radical hysterectomy and pelvic lymphadenectomy (RH-PLND).
PATIENTS AND METHODS: Patients with untreated stage IA2 to IIA adenocarcinoma (AD) or adenosquamous carcinoma (ASC) or nonbulky ( RESULTS: There were 36 SCCs, 20 ADs, and four ASCs. Of the 60 patients, 10 (16.7%) had pelvic LN metastases, and one (1.7%) had para-aortic LN (PALN) metastasis histologically. FDG-PET detected the single PALN metastasis (one of one patient) but detected only one (10%) of the 10 pelvic LN metastases. The PET false-negative pelvic LN micrometastases measured a median of 4.0 x 3.0 mm (range, 0.5 x 0.5 to 7 x 6 mm). The second stage of this trial will be continued without PET. CONCLUSION: This study shows that dual-phase FDG-PET has little value in primary, nonbulky, stage IA2 to IIA and MRI-defined, LN-negative cervical cancer.
Early-stage cervical cancer can be cured on an average rate of 80% with either radical surgery or definitive radiation. Pelvic lymph node (LN) metastasis is the most important prognostic factor in early-stage cervical cancer.1-3 Therefore, the evaluation of pelvic LN status becomes a crucial part in management. Magnetic resonance imaging (MRI) is better than computed tomography (CT) in defining tumor volume and depth of stromal invasion. Both methods rely on size and morphologic criteria to recognize LN metastasis, but small metastatic LNs are more often than not undetected.4-8 The [18F]-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) scan gives functional imaging of malignant cells. It has been shown to be superior to MRI and/or CT for evaluation of various malignancies.9 High sensitivity and specificity of FDG-PET in the detection of para-aortic LN (PALN) metastasis in patients with advanced/recurrent cervical cancer and in post-therapy surveillance has already been reported.10-16 A few investigators considered FDG-PET useful in detecting metastatic pelvic LNs,11,17,18 although controversial results have also been reported.13,19 However, the predictive value of PET in the assessment of pelvic LNs in early-stage cervical cancer is not yet clear. Sentinel LNs (SLNs) are the first LNs to receive lymphatic drainage from the primary tumor. When nodal metastases occur, SLNs will be initially involved. Therefore, the presence or absence of metastasis in the SLN should reflect the overall state of the entire drainage area. Aside from the success in melanoma and breast cancer, several reports advocate the use of SLN detection in cervical cancer.20-24 However, there has been no consensus reached because of limited sample sizes and various techniques of lymphatic mapping and SLN detection.25 We conducted a prospective study to investigate the potential benefits and limitations of combined FDG-PET and SLN identification in patients with early-stage cervical cancer undergoing radical surgery as the primary treatment. An interim analysis was performed when 60 patients were accrued, which led to the current report.
Study Population Eligible patients were cervical cancer patients scheduled to receive type II or III radical hysterectomy (RH) and pelvic lymphadenectomy (PLND)26 as the primary treatment and had to meet the following eligibility criteria: (1) histologically confirmed invasive carcinoma of the uterine cervix; (2) International Federation of Gynecology and Obstetrics (FIGO) stage IA2, IB, or IIA disease27; (3) squamous cell carcinoma (SCC; 4 cm by MRI) or adenocarcinoma (AD) or adenosquamous carcinoma (ASC) of any size; (4) MRI showed no suspicious LNs (score 2); (5) age 18 to 70 years; (6) no medical or surgical contraindications to RH-PLND; and (7) written informed consent. Patients with any of the following conditions were excluded: (1) small-cell carcinoma; (2) MRI showing suspected pelvic LNs (score 3) or SCC with MRI-defined cervical tumor diameter greater than 4 cm or stromal invasion greater than two thirds; (3) histologically proven metastasis to PALN; (4) ever received radiotherapy and/or chemotherapy for cervical cancer; (5) history of allergy to the radiotracer technetium-99msulfur colloid; (6) unable to cooperate with the PET or lymphoscintigraphic procedure, as judged by the physician in charge or nuclear medicine physician in charge; (7) a previous diagnosis of cancer other than nonmelanoma skin cancer; and (8) concomitant pregnancy.
MRI Imaging
PET Imaging
Image Analysis
For dual-phase PET, we combined early and late images to determine whether the lesion observed was fixed or not and to calculate changes in SUV from early to late results. Films of MRI/CT were analyzed separately by an experienced radiologist who was blinded to the FDG-PET results. The 5-point scoring criteria were also used for MRI/CT image interpretation and were as follows: score 0 = a normal finding; 1 = visible LNs less than 0.5 cm in size considered reactive and unrelated to metastasis; 2 = any LN of 1 cm or a little less in length, giving an overall equivocal impression; 3 = LNs more than 1 cm in length in the short axis and/or multiple LNs (n
Study Procedures and Determination of Lesion Status
Preoperative Lymphoscintigraphy
SLN Identification The radioactive LN, with a count equal to at least 10-fold greater than the background radiation level, was considered sentinel and removed after recording its location. The radioactivity of the SLN was measured ex vivo. After taking all SLNs, pelvic LN basins were scanned again to confirm no residual radioactivity 10-fold greater than the background. A complete PLND was then performed. The non-SLNs located below the bifurcation were considered as lower pelvic LNs. PALNs were not routinely dissected unless they were positive on preoperative FDG-PET or any LN metastasis was documented intraoperatively. RH was not required to be abandoned as a result of intraoperative proven LN metastasis.
Pathologic Evaluation Handling radioactive specimens was performed according to the recommendations of the College of Anatomic Pathologists.28 The other non-SLNs and the remainder of SLNs were fixed in 10% formalin for hematoxylin and eosin staining, whereas cytokeratin immunohistochemistry study was performed only for the remainder of each SLN.
Statistical Analysis
A total of 62 patients were registered initially. Two patients were not eligible because their initial diagnosis of cervical AD was changed to endometrial cancer after the protocol workups. These two patients were treated according to the endometrial cancer protocol, and their disease was proven by final pathology. The remaining 60 eligible patients completed preoperative and intraoperative surveys. Patient characteristics of the eligible patients are listed in Table 1.
Of the 60 patients, 10 (16.7%) had pelvic LN metastases and one (1.7%) had PALN metastasis histologically. Five (19.2%) of the 26 AD/ASC patients and five (13.9%) of the 36 SCC patients had pelvic LN metastases. The difference in LN metastatic rates between patients with AD/ASC and SCC was not significant (P = .5). FDG-PET detected the single PALN metastasis, but detected only one (10%) of the 10 pelvic LN metastases. The PET and histologic findings of patients with LN metastases are listed in Table 2. The median dimension (long x short axis) of metastatic LNs was 15 x 7 mm (range, 2 x 1 to 25 x 6 mm), and the median dimension of the cancerous component inside the nodes was 4.0 x 3.0 mm (range, 0.5 x 0.5 to 7 x 6 mm). In the single success of pelvic LN metastasis demonstrated by PET (patient 3), the metastatic foci measured 6 x 5 mm.
In contrast, the single PALN metastasis was found in an AD patient (patient 7) whose PALN and right common iliac and left external iliac LNs were identified as SLNs by lymphoscintigraphy (Fig 1A), and PALN metastasis was demonstrated by dual-phase PET with pelvic LN metastases undetected (PET was false negative; Figs 1B and 1C). CT-guided biopsy of PALN could not be performed because re-examining MRI failed to localize the PET-positive PALN (Fig 1D). The patient underwent exploration. The metastatic PALN contained a cancerous part measuring 5 x 2 mm (Fig 2).
The PET and histologic results of patients with metastatic LNs are listed in Table 3. On a patient basis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for detecting metastatic pelvic LNs with PET were 10%, 94%, 25%, 84%, and 80%, respectively. As a matter of fact, the stopping boundary of an extremely low sensitivity of PET ( 10%) was reached at the interim analysis. The protocol committee decided that the second stage of this trial will be continued with nonbulky stage IA2 to IIA SCC for SLN without PET. The further details for SLN will be reported after the trial is completed. However, for further exploring the role of FDG-PET in cervical AD/ASC, patients with AD/ASC will maintain PET with SLN detection (for tumor diameter 4 cm and stage IIA) or without SLN detection (for tumor diameter > 4 cm and stage IIB).
The diagnosis efficacy of FDG-PET in pelvic LN assessment compared with MRI or CT for early-stage cervical cancer is controversial. It is attractive to combine PET with SLN detection to investigate the potential benefits and limitations of sophisticated lymphatic mapping for the management of early cervical cancer. We are aware of no prior report using both PET and SLN mapping in this scenario. To our surprise, dual-phase FDG-PET detected only one (10%) of the 10 pelvic LN metastases in our series. The PET false-negative pelvic LN micrometastases measured up to 7.0 mm in diameter, whereas the metastatic foci measured 6 x 5 mm in the single success (patient 3) of PET. The clinical value of SLN detection depends on the detection rate and the negative predictive value of negative SLN. The SLNs were submitted for frozen section because we wanted to know whether frozen section would be good enough for abandoning removal of non-SLNs when SLNs were negative. The answers to these important questions will be revealed after the full study is completed. If the accuracy of frozen section should be unsatisfactory, the value of SLN procedures for guiding the extent of LN dissection in a one-stage surgery would be compromised. However, identifying SLNs could highlight which nodes should be examined with more intense pathologic evaluation. Reinhardt et al18 reported a prospective surgical/pathologic study of 35 FIGO stage IB to II cervical cancer patients who underwent RH-PLND and had a preoperative abdominal and pelvic FDG-PET and MRI. On a patient basis, LN staging resulted in a sensitivity of 91% with PET and 73% with MRI (P > .05). On an LN site basis, PET achieved a positive predictive value of 90%, and MRI achieved a positive predictive value of 64% (P < .05). In the series by Reinhardt et al,18 the overall pelvic LN metastasis rates was 31.4% (11 of 35 patients). Among these 11 patients with pelvic LN metastases, PET detected 10 metastases, and MRI detected eight metastases. As a matter of fact, of the MRI-negative patients (n = 27), only three had histologically proven pelvic LN metastasis, and PET detected two of these metastases. Narayan et al17 compared PET with CT/MRI in 27 stage IB to IV cervical cancer patients; PET detected 83% of pelvic LN metastasis (10 of 12 metastases) and MRI detected 50% of pelvic LN metastases (six of 12 metastases) in the 24 patients with assessable pelvic LNs. In their series, the pelvic LN metastasis rate was 50% (12 of 24 patients). Sugawara et al11 reported an 86% sensitivity rate with PET in seven cervical cancer patients (stage IB to IIB) with known LN metastases (one by surgical assessment and six by clinical follow-up). In contrast, Williams et al19 retrospectively reviewed 18 patients with gynecologic malignancies and MRI, CT, and PET scans before LN dissection (504 nodes obtained), 16 of whom had cervical cancers (14 primary and two recurrent cancers). Eight patients (50%) had 34 (6.7%) surgically proven metastatic pelvic LNs. On an individual nodal basis, the sensitivity rates were 53.7% for MRI, 48.1% for CT, and 24.5% for PET. Belhocine et al13 reported 22 untreated cervical cancer patients (FIGO stage unknown), of whom 18 underwent PLND. Five patients (27.8%) had pelvic LN metastasis. PET detected only two metastases (sensitivity: 40% on a patient basis and 20% on a nodal basis), whereas MRI detected five metastases. As a rule of thumb, the higher the ratios of histologic pelvic LN metastasis and/or simultaneous MRI/CT-positive pelvic LN, then the higher the sensitivity of PET will be expected. On the contrary, the added benefit of FDG-PET in a group of patients with negative MRI is relatively small. No patient was excluded for preoperative FDG-PETdetected occult metastasis in the current study. However, there were two patients with FIGO stage IB1 and IIA AD treated before the trial started whose solitary lung metastases were found by FDG-PET. Therefore, FDG-PET is not recommended before RH-PLND for early cervical SCC. Although it is still controversial whether AD/ASCs are more aggressive than their SCC counterparts stage for stage,31,32 they are relatively less well studied because of the limited number of cases. Therefore, we decided to continue to enroll all AD/ASC cervical cancer patients for PET study onto a separate trial regardless of type of primary treatment. In a recently published report, 29 cervical cancer patients and 15 endometrial cancer patients were enrolled onto a study to evaluate the diagnostic performance of nanoparticle-enhanced MRI. MRI was performed before (size criteria) and after the use of ultrasmall particles of iron oxide before lymphadenectomy. On a node by node basis, the sensitivity of detecting LN metastasis was significantly better using ultrasmall particles of iron oxide (93%) compared with size criteria alone (29%).33 It is still unknown whether this new approach could work as well for early-stage nonbulky cervical cancer. In conclusion, this study shows that dual-phase FDG-PET has little value in primary staging of nonbulky stage IA2 to IIA disease and MRI-defined LN-negative cervical cancer (especially SCC) before RH-PLND. Pragmatic use of this expensive imaging technology should be based on well-designed and well-conducted prospective studies targeting specific indications. It is also crucial that cost-effectiveness analyses of using PET scan according to clinical indications should be evaluated.34,35
The authors indicated no potential conflicts of interest.
Supported by Grants No. NSC-93-NU-7-182-003 from the National Science Council and the Institute of Nuclear Energy Research, Taiwan, and CMRPG32022 and CMRPG32029 from Chang Gung Memorial Hospital. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
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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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