Long-term weight loss after diagnosis may lower survival in colorectal cancer

Weight loss 5 years after colorectal cancer diagnosis appeared associated with lower long-term survival, study data showed.

“Growing evidence suggests that weight gain is associated with an increased risk [for] colorectal cancer,” Jonathan M. Kocarnik, PhD, of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues wrote. “To the best of our knowledge, fewer studies have evaluated adult weight change as it relates to colorectal cancer survival, but have suggested that postdiagnostic weight loss may be associated with lower survival.”

The researchers used four cancer registries to identify patients diagnosed with colorectal cancer from 1997 to 2008 (n = 2,049). Patients reported their height and weight 2 years before diagnosis, and researchers administered follow-up questionnaires 5 years after diagnosis. Kocarnik and colleagues used Cox regression analysis to evaluate associations between weight or BMI with OS and cancer-specific survival.

Most patients reported weight gain 5 years after diagnosis (53%; median weight gain, 5 kg), while 12% reported that their weight had not changed. Thirty-five percent reported weight loss (median, -4 kg).

During a median follow-up of 5.1 years, 344 patients died, 91 of whom died of colorectal cancer. Long-term weight loss appeared associated with lower OS (HR = 1.13; 95% CI, 1.07-1.21), as well as lower colorectal-cancer specific survival (HR = 1.25; 95% CI, 1.13-1.39).

Relative weight loss (>5% vs. ≤5% change), change in BMI category (overweight to normal vs. remaining overweight) and BMI reduction also appeared linked with lower long-term survival.

“The findings of the current study suggest the importance of avoiding weight loss among long-term survivors of colorectal cancer, even among those who are overweight or obese,” the researchers wrote.

Kocarnik and colleagues acknowledged that these findings conflicted with guidelines, which advise patients to “achieve and maintain a normal weight.

“Patients and physicians should be aware of the potential decreased survival among those patients who experience weight loss after colorectal cancer, even many years after diagnosis,” the researchers wrote. “Additional research is warranted to evaluate the additional contribution of diet, physical activity and body composition for colorectal cancer survival within the context of weight change after diagnosis.”

Researchers also suggested future research evaluate whether the weight change is intentional or marks declining health. – by Andy Polhamus

Disclosures: Kocarnik reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.