ASCO 2014 Report: First line treatment efficacy in colorectal cancer affected by gender and tumor location

by Bruce Sylvester – Gender and tumor location predict efficacy in first-line treatment metastatic colorectal cancer, researchers reported a poster presentation at ASCO 2014.

In the FIRE-3, investigators compared first-line therapy with FOLFIRI plus either cetuximab or bevacizumab in 592 KRAS exon 2 wild-type metastatic colorectal cancer. In this newly-reported sub-analysis of FIRE-3, the investigators  analyzed the efficacy of the same regimens by gender and primary tumor location within a RAS wild-type population (n=342).

They defined primary tumor location as:  right sided colorectal cancer :  coecum to hepatic flexure; left sided colorectal cancer : splenic flexure to rectum. They excluded colon transversum tumors (n=9).

They calculated differences in overall response rate, progression-free survival and overall survival in both treatment arms using standard analytical and statistical tools.

They found that, for location, left sided colorectal cancer had better efficacy results fo r response and both survival measures, when compared with right sided colorectal cancer, reaching statistical significance in the cetuximab arm for both progression-free survival (<0.0001) and overall survival (<0.0001)

Women trended toward lower tumor response rates, shorter progression-free survival and shorter overall survival compared to men.

The authors concluded, “Treatment efficacy depends on primary tumor location and patients’ gender. Effects were more prominent in patients receiving FOLFIRI plus cetuximab where male patients with LCRC [left sided colorectal cancer ] tumors are favored.”

Citation: 2014 ASCO Annual Meeting; General Poster Session, Gastrointestinal (Colorectal) Cancer Abstract No 3600