The Cancer-Weight Connection: Five Key Findings

When it comes to cancer, weight matters. 

American Cancer Society researchers have been studying the connections between weight and cancer since publishing the first epidemiological evidence that obesity increases risk of death from all causes – as well as from cancer and cardiovascular disease – in 1979. That finding came from the long-term follow-up study, Cancer Prevention Study I (CPS-I).

Society researchers have continued to make major discoveries in this area, uncovering the following five key findings from Cancer Prevention Study II (CPS-II):

1. Being overweight or obese poses great risk: A person’s risk of developing or dying from several cancers – breast, colon and rectum, endometrial, esophagus, pancreas, and kidney, among others – is greatly increased if he or she is at an unhealthy weight. Additionally, men and women with high waist circumferences are also at increased risk for cancer death.

2. Physical activity, proper diet lowers risk: In part because it helps people maintain a healthy weight, exercise reduces cancer risk for certain types of cancers including postmenopausal breast, colon, and endometrial. More broadly, men and women whose lifestyle conformed to ACS Guidelines for Nutrition and Physical Activity had a significantly lower risk of death from cancer.

3. Sitting too much may up risk: For women – even those who are physically active – spending too much time sitting is associated with an increased chance of dying from cancer.

4. Weight cycling does not appear to increase mortality: Multiple cycles of weight loss and gain do not appear to increase cancer mortality for men and women, so people who are overweight or obese should continue to be encouraged to lose weight.

5. Colorectal cancer survival worse for those very overweight: Those who are very overweight and obese have poorer survival after a colorectal cancer diagnosis.

CPS-II and other Society studies have also led to many more findings about the links between weight and cancer.