Rankin, Cathyrn

Abstract Purpose: Obesity is associated with an increased risk of colon cancer. However, the influence of body mass index (BMI) upon the outcome of colon cancer survivors and its relationship to gender remains unknown. Experimental Design: BMI (kg/m2) was calculated and categorized in patients with TNM stage II and III colon carcinomas (n= 4,381) enrolled in 7 randomized trials of 5-fluorouracil-based adjuvant chemotherapy. Cox proportional hazards modeling was used to determine the association of BMI with disease-free and overall survival. Results: Among colon cancer patients, 868 (20%) were obese (BMI ≥30 kg/m2) of which 606 were class 1 (BMI 30–34 kg/m2) and 262 were class 2,3 (BMI ≥35 kg/m2). Obese versus normal-weight patients were more likely to be younger, have distal tumors, show intact DNA mismatch repair (MMR), and have increased lymph node metastases (p <0.017). The association of BMI and MMR status was dependent upon patient age (p= 0.031). In a multivariate analysis, BMI was significantly associated with both disease-free (p=0.030) and overall survival (p=0.0017). Men with class 2,3 obesity showed reduced overall survival compared to normal weight men [HR 1.35 (1.02, 1.79); p=0.039]. Women with class I obesity had reduced overall survival [HR 1.24 (1.01, 1.53), p=0.045] compared to normal weight women. BMI was not predictive of therapeutic benefit. Conclusions: Obesity is associated with intact DNA mismatch repair status and was an adverse, independent prognostic variable in colon cancer survivors. Interventions to reduce obesity have the potential to improve patient outcomes in colon cancer survivors. Citation Information: Cancer Prev Res 2010;3(1 Suppl):B111.

Abstract Purpose: Obesity is associated with an increased risk of colon cancer. However, the influence of body mass index (BMI) upon the prognosis of colon cancer survivors and its relationship to gender remains unknown. Experimental Design: BMI (kg/m2) was categorized in patients with TNM stage II and III colon carcinomas (n= 4,381) enrolled in 7 randomized trials of 5-fluorouracil-based adjuvant chemotherapy. Cox proportional hazards models were used to determine the association of BMI with disease-free (DFS) and overall survival (OS). Results: Among colon cancer patients, 868 (20%) were obese (BMI >30 kg/m2) of which 606 were class 1 (BMI 30-34 kg/m2) and 262 were class 2,3 (BMI >35 kg/m2). Obese versus normal-weight patients were more likely to be younger (p=0.038), have distal tumors (0.058), show intact DNA mismatch repair (MMR) (p=0.035), and have more lymph node metastases (p=0.017). In a multivariate analysis, BMI was significantly associated with both DFS (p=0.030) and OS (p=0.0017). Men with class 2,3 obesity showed reduced OS compared to normal weight men [HR 1.35 (1.02, 1.79); p=0.039]. Women with class I obesity had reduced OS [HR 1.24 (1.01, 1.53), p=0.045] compared to normal weight women. Overweight status was associated with improved OS in men (p= 0.006) and underweight women had significantly worse OS (p= 0.019). BMI was not predictive of therapeutic benefit. Conclusions: Obesity is an independent prognostic variable in colon cancer survivors and shows gender-related differences. These data suggest that obesity-related biological factors can influence clinical outcome. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 904.