Tuesday, December 27, 2011 (Last Updated: 12/28/2011)TUESDAY, Dec. 27 (HealthDay News) -- Obese patients with colon cancer are less likely to have deficient mismatch repair (dMMR) tumors and have a worse prognosis compared with normal-weight patients, independent of other tumor variables, according to a study published online Dec. 27 in the Journal of Clinical Oncology.
Frank A. Sinicrope, M.D., of the Mayo Clinic in Rochester, Minn., and colleagues analyzed data from 2,693 patients with TNM stage II or III colon carcinomas who participated in North Central Cancer Treatment Group (NCCTG) or National Surgical Adjuvant Breast and Bowel Project (NSABP) randomized trials of adjuvant chemotherapy. The associations between body mass index (BMI) and MMR status, and BMI and survival, were analyzed by logistic regression and Cox models, respectively.
The researchers found that, overall, 16 percent of tumors showed dMMR and 23 percent of patients were obese (BMI, ≥30 kg/m²). Obesity was significantly associated with lower rates of dMMR tumors, even after adjusting for tumor site, tumor stage, sex, and age. Obese patients with colon cancer had significantly higher recurrence rates, shorter time to recurrence, worse disease-free survival (DFS), and worse overall survival (OS) rates compared with normal-weight patients, even after adjusting for other variables. Rates of dMMR were higher in obese women than in obese men (13 versus 8 percent). Patients with dMMR colon cancers had significantly longer DFS and OS than patients with proficient MMR tumors.
"Colon cancers from obese patients are less likely to show dMMR, suggesting obesity-related differences in the pathogenesis of colon cancer. Although obesity was independently associated with adverse outcome, the favorable prognostic impact of dMMR was maintained among obese patients," the authors write.
Hematology & Oncology
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