Knowing how much exercise is enough to prevent health problems can be confusing, but two recent studies have shown that years of physical inactivity prior to diagnosis was associated with increased risk of developing ovarian cancer and of dying from the disease.

The research is based on two large pooled analyses of several studies from the Ovarian Cancer Association Consortium.

The investigations were published online ahead of print in Cancer Epidemiology, Biomarkers & Prevention (CEBP) and the British Journal of Cancer (BJC).

“Women may be overwhelmed with mixed messages about physical activity or exercise recommendations and opt to be inactive because they feel that they cannot meet the recommended amount of physical activity. Our findings suggest that any amount of regular, weekly recreational physical activity may reduce the risk for and improve survival from ovarian cancer, while a lack of regular exercise throughout adulthood is associated with an increased risk of developing and dying from ovarian cancer,” says Kirsten Moysich, PhD, MS, senior author of the studies and Distinguished Professor of Oncology in the Department of Cancer Prevention and Control at Roswell Park.

The study published in CEBP evaluated nine studies from the Ovarian Cancer Association Consortium, and included 8,309 ovarian cancer patients and a control group of 12,612 women without cancer.

Women who reported a lifetime of recreational physical inactivity had a 34% increased risk of being diagnosed with ovarian cancer — findings that are similar to the results of a companion study in cervical cancer.

The association between inactivity and ovarian cancer risk was seen in both normal-weight and overweight or obese women.

The BJC study included 6,806 women diagnosed with invasive epithelial ovarian cancer, and evaluated the association between recreational physical inactivity in the years prior to diagnosis and the risk of mortality after diagnosis.  

Inactive women had between 22% and 34% higher risk of mortality compared to women reporting at least some regular weekly activity.

Again, the findings were seen in both normal-weight and overweight women.

“While the current evidence regarding the association between different amounts of physical activity and ovarian cancer remains mixed, our findings demonstrate that chronic inactivity may be an important independent risk and prognostic factor for ovarian cancer,” says Rikki Cannioto, PhD, EdD, Research Affiliate in the Department of Cancer Prevention and Control at Roswell Park and first author on both studies. “Given the prevalence of physical inactivity at the population level, these findings could have important public health and clinical implications, particularly in the context that few modifiable prognostic factors have been previously identified for ovarian cancer, and only modest improvements in ovarian cancer survival have occurred in recent decades.”

“Less than 45% of women who are diagnosed with ovarian cancer will survive for five years,” says Professor Penny Webb, PhD, Group Leader at QIMR Berghofer Medical Research Institute in Australia and a co-author of both papers. “Given the poor prognosis, many women want to know what they can do to reduce their risk of getting ovarian cancer and to improve their prognosis once diagnosed. These studies suggest that regular physical activity could help.”

Sources: BJC & CEBP