Body Mass Index and Body Surface Area and Their Associations with Outcomes in Stage II and III Colon Cancer

Our study aims were to measure the associations between body mass index (BMI) and body surface area (BSA) with outcomes for stage II and III colon cancer and to evaluate if the effect of obesity is modified by disease stage and receipt of adjuvant therapy.

Using a prospective cohort of stage II and III colon cancer patients who were referred between 2001 and 2005, we compared 3-year relapse-free survival (3-year RFS), 5-year cancer-specific survival (5-year CSS), and 5-year overall survival (5-year OS) rates among different BMI and BSA categories. Cox proportional-hazards models were constructed to explore the relationships between different body compositions and outcomes while adjusting for confounders.

Postoperative height and weight were used to classify 913 patients as normal weight (n = 424, BMI <25 kg/m²), overweight (n = 319, BMI 25–30 kg/m²), and obese (n = 170, BMI >30 kg/m²). Using Mosteller formula, 684 subjects had normal BSA (≤2.0 m²) and 229 had high BSA (>2.0 m²). Obese subjects experienced similar 3-year RFS (61.9 vs. 66.5 vs. 63.6 %, p = 0.51), 5-year CSS (65.6 vs. 72.4 vs. 68.0 %, p = 0.22), and 5-year OS (60.8 vs. 64.0 vs. 62.2 %, p = 0.69) when compared to overweight subjects and those with normal BMIs, respectively. Likewise, individuals with high BSA had similar outcomes as those with normal BSA (66.2 vs. 63.6 %, p = 0.64 for 3-year RFS, 70.3 vs. 68.6 %, p = 0.62 for 5-year CSS, and 64.5 vs. 61.9 %, p = 0.48 for 5-year OS). In Cox models, advanced age, male gender, stage III disease, and poor performance status correlated with inferior RFS, CSS, and OS, but BMI and BSA did not.

Obesity as measured by either BMI or BSA was not associated with differences in outcomes in stage II and III colon cancer.