Overweight Colorectal Cancer Patients Outlive Those With the Lowest BMI, New Study Finds

A new study presented at the European Society for Medical Oncology 17th World Congress on Gastrointestinal Cancer 2015 found that metastatic colorectal cancer (mCRC) patients with higher body mass index (BMI) outlived patients with the lowest BMI. Those who had the lowest BMI lived on average 2-and-a-half months less than patients who were overweight or obese.

The study examined over 6000 patients who were treated with bevacizumab alongside chemotherapy and were participating in a trial that examined overall survival and progression-free survival.

Initially researchers believed that obese patients would respond more poorly to treatments for stage 4 colorectal cancer because previous studies have shown a positive relationship between obesity and increased risk for colorectal cancer.

Lead study author Yousuf Zafar, MD, MHS, associate professor of medicine at Duke Cancer Institute in Durham, North Carolina, suggested that lower weight patients may have received an adequate first-line treatment but then became too sick to receive subsequent lines of therapy. He added that cancer-related cachexia, or progressive weight loss due to severe chronic illness, may have overwhelmed any harm from obesity.

“An important next step in this work would be a closer study of how cachexia worsens patient outcomes in mCRC,” Dr Zafar said in a statement. “We need to understand whether it is the biology of cachexia that harms these patients more, or whether their outcome is worsened by receipt of sub-par treatment. Or it could be a combination of both.”

While the study found that patients of differing BMI’s survived at different rates, patients of all weight classes experienced similar rates of progression-free survival.