BMI at the time of and after diagnosis of colorectal cancer was linked with mortality risk, according to a retrospective observational study involving more than 3,400 individuals.

Participants were between 18 and 80 years of age, were diagnosed with stage I to III colorectal cancer, and also had surgery. Investigators measured BMI at diagnosis and 15 months later. Among the results:

• At diagnosis, those whose BMI was <18.5, as well as those whose BMI was ≥35, had increased mortality risks.

• Conversely, patients who were high-normal weight (BMI 23 to <25), low-overweight (BMI 25 to <28), and high-overweight (BMI 28 to <30) had lower mortality risks.

• Those with BMI between 30 and <35 showed no difference in risk.

• Links between post-diagnosis BMI and mortality were similar, but patients with BMI between 30 and <35 had significantly lower mortality risks.

The authors concluded that recommending weight loss right after diagnosis in those who are overweight may be unwarranted.

Citation: Kroenke C, Neugebauer R, Meyerhardt J, et al. Analysis of body mass index and mortality in patients with colorectal cancer using causal diagrams. [Published online ahead of print May 19, 2016]. JAMA Oncol. doi:10.1001/jamaoncol.2016.0732.