Higher BMI linked to improved survival for patients with metastatic colorectal cancer

Issue: June 25, 2016

CHICAGO — Overweight and obese patients with metastatic colorectal cancer experienced significantly prolonged OS compared with normal weight patients, according to the results of a pooled analysis presented at the ASCO Annual Meeting.

Further, patients with metastatic colorectal cancer who had BMI below 18.5 experienced significantly worse OS and PFS.

“We confirm previous research that obesity improves outcomes for patients with metastatic colorectal cancer and also that patients classified as thin experience poor prognosis,” Thomas Aparicio, MD, PhD, gastroenterology professor at Avicenne Hôpital, Assistance Publique-Hopitaux de Paris in France, told HemOnc Today. “Notably, bevacizumab [Avastin, Genentech] is effective in obese and nonobese patients at the same rate, but the reason behind the improved prognosis remains unknown; some think that immune modulation or chemotherapy tolerance may be a factor.”

Previous research has shown having a high or low BMI is associated with poor prognosis in early-stage colorectal cancer, and low BMI is associated with poor prognostic in metastatic colorectal cancer.

Aparicio and colleagues assessed metastatic colorectal cancer outcomes according to BMI at various time points, as well as how BMI impacted therapy dose reductions.

The analysis included data from 2,085 patients who were enrolled into one of eight Fédération Francophone de Cancérologie Digestive (FFCD) first-line metastatic colorectal cancer trials between 1991 and 2013.

Twelve percent of patients enrolled were obese (BMI > 30), including 7.7% who were obese during 1991 to 1999, 14.5% who were obese during 2000 to 2006, and 13.6% who were obese during 2007 to 2013.

Researchers grouped patients by BMI and compared obese patients (BMI 30) to patients classified as normal or overweight and compared patients classified as skinny (BMI < 18.5) to non-skinny patients (BMI > 18.5).

Compared to normal and overweight patients (BMI, 18.5 -29), obese patients experienced longer median OS (19.5 months vs. 16.6 months; HR = 1.15; 95% CI, 1-1.33) but comparable median PFS (7.9 months vs. 7.3 months; HR = 1.06; 95% CI, 0.93-1.22) and objective response rate (42% vs. 38.5%; OR = 1.02; 95% CI, 0.77-1.37).

When researchers evaluated patients with a BMI above vs. below 25, they found patients with the higher BMI experienced significantly prolonged OS (18.5 months vs. 16.3 months; HR = 1.13; 95% CI, 1.02-1.25) and a higher ORR (42% vs. 36%; OR = 1.23; 95% CI, 1.01-1.5).

Results of subgroup analyses showed obesity was associated with improved outcomes among men for OS (P = .03) and PFS (P = .05).

Patients with a BMI less than 18.5 had lower OS (HR = 0.75; 95% CI, 0.6-0.94) and PFS (HR = 0.75; 95% CI, 0.6-0.93).

A greater proportion of patients classified as obese experienced dose reductions in the first cycle than patients classified as normal/overweight (34% vs. 17%; P < .001).

“One of the limitations was the lack of detailed obesity data and biological profiles. We need to further analyze the role of BMI in patients with metastatic colorectal cancer by comparing the biologic profiles of patients classified as thin and obese,” Aparicio said. – by Nick Andrews

Reference:

Aparicio T, et al. Abstract 3532. Presented at: ASCO Annual Meeting; June 3-7, 2016; Chicago.

Disclos ure: Aparicio reports consultant/advisory roles with and speakers’ fees from Roche, speakers fees from Sanofi, and travel expenses from Ipsen and Novartis. Please see the abstract for a list of all other researchers’ relevant financial disclosures.