Obesity is an independent prognostic variable in colon cancer survivors.
OBJECTIVE
Obesity is associated with an increased risk of colon cancer. However, the influence of body mass index (BMI) on the prognosis of colon cancer survivors and its relationship to gender remains unknown.


METHODS
BMI (kg/m(2)) was categorized in patients with tumor-node-metastasis stage II and III colon carcinomas (n = 4,381) enrolled in seven randomized trials of 5-fluorouracil-based adjuvant chemotherapy. Cox proportional hazards models were used to determine the association of BMI with disease-free survival (DFS) and overall survival (OS).


RESULTS
Among colon cancer patients, 868 (20%) were obese (BMI, >or=30 kg/m(2)), of which 606 were class 1 (BMI, 30-34 kg/m(2)) and 262 were class 2,3 (BMI, >or=35 kg/m(2)). Obese versus normal-weight patients were more likely to be younger, have distal tumors, show intact DNA mismatch repair, 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 with normal-weight men [hazard ratio, 1.35; 95% confidence interval, 1.02-1.79; P = 0.039]. Women with class I obesity had reduced OS [hazard ratio, 1.24; 95% confidence interval, 1.01-1.53; P = 0.045] compared with 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.
Sinicrope
Frank A
FA
Divisions of Oncology and Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA. sinicrope.frank@mayo.edu
Foster
Nathan R
NR
Sargent
Daniel J
DJ
O'Connell
Michael J
MJ
Rankin
Cathryn
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D001823:Body Composition; D015992:Body Mass Index; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D004249:DNA Damage; D004260:DNA Repair; D018572:Disease-Free Survival; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D009367:Neoplasm Staging; D009765:Obesity / Q000150:complications* / Q000175:diagnosis; D050177:Overweight; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D017741:Survivors; D016896:Treatment Outcome; D055815:Young Adult
D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil