YALE CANCER SCIENTIST YALE CANCER SCIENTIST
HEALTH I-TEAM SCIENTIST JENNIFER FRANK CONN

Research: breast cancer treatment should address obesity Jenifer FrankConn. Health I-Team Writer Published 3:23pm, Friday, December 26, 2014 Yale cancer scientist Melinda Irwin says that the connection between obesity and cancer are so strong – as are recent findings about the effectiveness of exercise and diet in treating cancer – that pharmaceutical companies should be required to include these two lifestyle components in drug trials. Photo: Contributed Photo, Jenifer Frank/Contributed Photo

0

ACCORDING TO Yale cancer scientist Melinda Irwin says that the connection between obesity and cancer are so strong — as are recent findings about the effectiveness of exercise and diet in treating cancer — that pharmaceutical companies should be required to include these two lifestyle components in drugtrials.

A mandate is needed, Irwin said, because the pharmaceutical industry, which funds most large-scale drug trials, "has no incentive to fund lifestyle behavioral interventions. Why would they? There’s no pill totake."

Irwin studies the effects of weight loss and exercise on breast cancer survivors. Her comments echo those by the American Society of Clinical Oncology, which has issued a new position paper calling obesity "a major unrecognized risk factor forcancer.”

"As many as 84,000 cancer diagnoses each year are attributed to obesity, and overweight and obesity are implicated in 15 percent to 20 percent of total cancer-related mortality," the group says in its position paper published in the online version of the Journal of Clinical Oncology Oct.1.

It calls for medical school curriculums to be revamped to teach oncologists how to help their patients "lose weight and make other healthy lifestylechanges."

The National Cancer Institute says obesity is linked to poorer outcomes in cancer patients, undercuts the effectiveness of drugs to treat cancer and may increase a patient’s risk of developing new cancers and other diseases. Obesity has been associated with greater risks of postmenopausal breast cancer and colon cancer and cancers of the prostate, kidney, pancreas, esophagus, gallbladder andothers.

Exercise reducesrisk

Medical advances in breast cancer treatment over the past 30 years have spurred some researchers to focus now on how to keep the increasing numbers of survivorshealthy.

Earlier in her career, Irwin studied cancer prevention, finding that moderate physical activity decreased levels of estrogen, a hormone that can be associated with breast cancer, by about 10 percent, an outcome she calls "totallysignificant."

Since then, Irwin, the co-program leader of Cancer Prevention and Control Research at the Yale Cancer Center, has focused on breast cancer survivors who are overweight and obese, also doing some research into patients with ovariancancer.

In 2008, she published the Yale Exercise and Survivor Study (YES), which looked at the effect of aerobic exercise — in this case, brisk walking– on levels of insulin and "insulin-like growth factors" (IGF) in postmenopausal breast cancer survivors. Insulin and IGF can be signs, or "biomarkers," of increased risk of breastcancer.

The study showed that the women who exercised moderately — about 30 minutes of walking five days a week — had lower insulin rates than the more sedentarygroup.

The following year, in a second YES study, Irwin examined the effects of moderate exercise on body composition, including weight and bone mineral density, among breast cancer survivors. Breast cancer survivors often gain weight, partly as a result of their treatment. Also, they are often more vulnerable to bone fractures, because the cancer drugs decrease bone mineraldensity.

This second YES study showed positive changes in body composition among the women who participated in moderate aerobicexercise.

"I was always interested in exercise because it’s always sort of a stepchild to weight anddiet,"

Irwin said. "You always hear about weight and diet, and exercise is never really considered. And yet there are significant direct effects of exercise, independent of body weight, or BMI [body mass index], on certainoutcomes."

She said breast cancer survivors who were exercising a few years after their diagnosis "had about a 50 percent lower risk of recurrence or mortality, compared to those notexercisi