Obesity, Physical Activity Linked to Risk in Subset of Colorectal CA

Obesity, Physical Activity Linked to Risk in Subset of Colorectal CA
Obesity, Physical Activity Linked to Risk in Subset of Colorectal CA

(HealthDay News) – Obesity and physical inactivity are associated with a higher risk of WNT/β-catenin (CTNNB1)-negative colorectal cancer, but are not associated with CTNNB1-positive cancer risk, according to a study published online Feb. 26 in Cancer Research.

To examine whether tumor CTNNB1 status influences cellular sensitivity to obesity and physical activity, Teppei Morikawa, MD, PhD, from the Dana-Farber Cancer Institute in Boston, and colleagues used tissue immunohistochemistry data on nuclear CTNNB1 expression from 861 incident rectal and colon cancers identified during follow-up of 109,046 women in the Nurses' Health Study and 47,684 men in the Health Professionals Follow-up Study.

The researchers found that greater body mass index correlated with a significantly elevated risk of CTNNB1-negative cancer (multivariate hazard ratio [HR], 1.34 for 5kg/m2 increment; Ptrend = 0.0001) but not with the risk of CTNNB1-positive cancer (multivariate HR, 1.07 for 5kg/m2 increment; Ptrend = 0.36). There was a significantly lower risk of CTNNB1-negative cancer with higher physical activity levels (multivariate HR, 0.93 for 10 metabolic equivalent task [MET]-hours/week increment; Ptrend = 0.044) but no association with CTNNB1-positive cancer risk (multivariate HR, 0.98 for 10 MET-hours/week increment; Ptrend = 0.6).

"These data suggest that energy balance status exerts its effect in a specific carcinogenic pathway that is less likely dependent on WNT/ CTNNB1 activation," write the authors. "In the future, we may be able to identify individuals who are susceptible to the development of CTNNB1-negative tumors, and lifestyle preventive measures can be taken."

Abstract
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