Influence of body mass index on outcomes and treatment-related toxicity in patients with colon carcinoma

BACKGROUND. Obesity is a risk factor for the development of colon carcinoma. The influence of body mass index (BMI) on long-term outcomes and treatment-related toxicity in patients with colon carcinoma has not been well characterized. METHODS. This cohort study was conducted within a large, randomized adjuvant chemotherapy trial of 3759 men and women with high-risk, Stage II and Stage III colon carcinoma who were treated between 1988 and 1992 throughout the United States. With a median follow-up of 9.4 years, the authors examined the influence of BMI on disease recurrence, overall survival, and treatment-related toxicity. RESULTS. Compared with women of normal weight (BMI, 21.0-24.9 kg/m²), obese women with colon carcinoma (BMI ≥ 30.0 kg/m²) experienced significantly worse overall mortality (hazard ratio [HR], 1.34; 95% confidence interval [95% CI], 1.07-1.67) and a nonsignificant increase in the risk of disease recurrence (HR, 1.24; 95% CI, 0.98-1.59). The influence of BMI among women was not related to any differences in chemotherapy dose-intensity across categories of BMI. In contrast, BMI was not related significantly to long-term outcomes among male patients in this cohort. Among all study participants, obese patients had significantly lower rates of Grade 3-4 leukopenia and lower rates of any Grade ≥ 3 toxicity compared with patients of normal weight. CONCLUSIONS. Among women with Stage II-III colon carcinoma, obesity was associated with a significant increase in overall mortality as well as a borderline significant increase in disease recurrence. Nonetheless, obesity was not associated with any increase in chemotherapy-related toxicity.