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Originally published as JCO Early Release 10.1200/JCO.2008.20.8827 on February 17 2009 © 2009 American Society of Clinical Oncology.
Impact of Body Mass Index on Colorectal Cancer Treatment and Outcomes: Need for Prospective and Comprehensive DataDepartment of Medical Oncology, Royal Melbourne Hospital; BioGrid Australia, Melbourne; and Department of Medical Oncology, Western Hospital, Parkville, Victoria, Australia
Department of Surgery, Western Hospital, Parkville, Victoria, Australia
Department of Surgery, Royal Melbourne Hospital, Melbourne, Victoria, Australia
Department of Surgery, Box Hill Hospital, Box Hill, Victoria, Australia
Department of Medical Oncology, Royal Melbourne Hospital; BioGrid Australia, Melbourne; and Department of Medical Oncology, Western Hospital, Parkville, Victoria, Australia
Department of Medical Oncology, Royal Melbourne Hospital, Melbourne; and Department of Medical Oncology, Western Hospital, Parkville, Victoria, Australia
Department of Medical Oncology, Royal Melbourne Hospital; BioGrid Australia; Ludwig Institute for Cancer Research, Melbourne; and Department of Medical Oncology, Western Hospital, Parkville, Victoria, Australia To the Editor: The recent article by Meyerhardt et al1 adds to the increasing literature suggesting a greater risk of cancer recurrence in the obese patient.2–4 However, the impact of obesity in routine clinical care, including patient enrolment onto clinical trials, has yet to be explored. Also, the challenge of isolating the effect of body mass index (BMI) from that of the multiple associated factors that may also influence patient outcomes is worthy of additional discussion. To inform these issues, we present analyses from a prospective database of colorectal cancer (CRC) patients treated at five Victorian hospitals between 2000 and 2008. Data for 1,099 patients were examined, including 609 males and 490 females, with a median age of 67.95 years (range, 15.28 to 96.79 years). In the study by Meyerhardt et al, the obese patients were a median 8 years younger than the normal-weight patients (median 55 v 63 years). Analysis of our clinical series (Table 1) revealed a similar difference (median 61.9 v 69.6 years; P < .0001). Although, as expected, the median age of a trial population is younger, enrollment on the study analyzed by Meyerhardt et al seems representative of the BMI distribution of the general CRC population. Consistent with this impression, in our cohort there was no apparent influence of BMI on trial entry, with the BMI distribution of the total of 186 patients with stage IV cancer at presentation being similar to the subset of 61 patients who were trial participants (Fig 1).
Study of stage II and III CRC patients revealed that obese patients seem to be receiving adjuvant chemotherapy at similar rates to their fellow normal-weight patients (Table 1), although this could be confounded by the relationship between age (a major influence on chemotherapy use5) and obesity. Of potential concern was a trend for delayed initiation of treatment in obese patients (nine of 25 [36.0%]) compared with normal-weight patients (16 of 78 [20.5%]); this requires additional study, given that the median age of the obese patients is much younger. As discussed by Meyerhardt et al, arbitrary dose reductions in the obese patient are common, even in the clinical trial setting, and these alone could account for inferior outcomes in patients with a high BMI.3,6 A previous publication from this group also demonstrated that diabetes significantly increased the risk of cancer recurrence,7 but this was not mentioned in the current study, presumably because the data were not available. As seen in Table 1, we found a clear relationship between increasing BMI and diabetes, steadily increasing from a low of 6% of underweight patients, through 14% of normal weight patients, to 37% of obese patients (P < .0001). This suggests that the effect of either BMI or diabetes cannot be reliably examined in isolation. Our data provide reassurance that obese patients are being enrolled onto clinical trials, and this adds weight to the assertion by Meyerhardt et al that their study population is likely representative of the general CRC population. However, we would suggest that in the absence of data on multiple potential confounding factors, including chemotherapy dosing and diabetes, the specific relationship between obesity and cancer outcomes remains uncertain. Furthermore, although obese patients seem to be receiving standard care, additional exploration of the impact of obesity on the time to initiation of adjuvant chemotherapy is also warranted. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The author(s) indicated no potential conflicts of interest. REFERENCES
1. Meyerhardt JA, Niedzwiecki D, Hollis D, et al: Impact of body mass index and weight change after treatment on cancer recurrence and survival in patients with stage III colon cancer: Findings from Cancer and Leukemia Group B 89803. J Clin Oncol 26:4109–4115, 2008. 2. Meyerhardt JA, Tepper JE, Niedzwiecki D, et al: Impact of body mass index on outcomes and treatment-related toxicity in patients with stage II and III rectal cancer: Findings from Intergroup Trial 0114. J Clin Oncol 22:648–657, 2004. 3. Dignam JJ, Polite BN, Yothers G, et al: Body mass index and outcomes in patients who receive adjuvant chemotherapy for colon cancer. J Natl Cancer Inst 98:1647–1654, 2006. 4. Meyerhardt JA, Catalano PJ, Haller DG, et al: Influence of body mass index on outcomes and treatment-related toxicity in patients with colon carcinoma. Cancer 98:484–495, 2003.[CrossRef][Medline] 5. Ananda S, Field KM, Kosmider S, et al: Patient age and comorbidity are major determinants of adjuvant chemotherapy use for stage III colon cancer in routine clinical practice. J Clin Oncol 26:4516–4517, 2008 author reply 4517-4518. 6. Lyman G: Undertreatment of cancer patients with chemotherapy is a global concern. J Oncol Pract 4:114–115, 2008. 7. Meyerhardt JA, Catalano PJ, Haller DG, et al: Impact of diabetes mellitus on outcomes in patients with colon cancer. J Clin Oncol 21:433–440, 2003.
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Copyright © 2009 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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