Physical inactivity may be independent risk, prognostic factor for ovarian cancer

Years of physical inactivity prior to ovarian cancer diagnosis appeared associated with increased risk for and mortality from the disease, according to results of two studies.

Kirsten Moysich, PhD, MS, distinguished professor of oncology in the department of cancer prevention and control at Roswell Park Cancer Institute, and colleagues sought to measure the effect of physical inactivity on ovarian cancer risk and outcomes.

Kirsten Moysich

The study — results of which appeared in Cancer Epidemiology, Biomarkers & Prevention — included data from 8,309 women with ovarian cancer in the Ovarian Cancer Association Consortium, as well as 12,612 women without cancer.

Women who reported a lifetime of physical inactivity demonstrated a 34% increased risk for ovarian cancer. Researchers observed the elevated risk among women of normal weight, as well as those who were overweight or obese.

In a separate study, Rikki Cannioto, PhD, EdD, research affiliate in the department of cancer prevention and control at Roswell Park, and colleagues evaluated the association between recreational physical inactivity prior to diagnosis and mortality risk after diagnosis.

The study — results of which appeared in British Journal of Cancer — included data from 6,806 women diagnosed with invasive epithelial ovarian cancer.

Results showed inactive women had a 22% to 34% greater risk for mortality after diagnosis than women who reported regular weekly activity. Once again, researchers observed the elevated risk among normal-weight and overweight women.

“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,” Moysich said in a press release. “Our findings suggest that any amount of regular, weekly recreational physical activity may reduce the risk for and improve survival from ovarian cancer, whereas a lack of regular exercise throughout adulthood is associated with an increased risk for developing and dying of ovarian cancer.”

HemOnc Today spoke with Moysich — involved with both studies — about the potential implications of the results.

Question: What prompted this research?

Answer: There was literature on physical activity and ovarian cancer risk, but the findings were very inconsistent. We believe this is because physical activity is difficult to assess correctly. Both women and men overestimate their physical activity, so we do not really have an accurate measure. We thought most participants would not exaggerate their levels of inactivity because no one is proud of being inactive. By focusing on inactivity, we may overcome some of the limitations associated with studying physical activity.

Q: Why are these results important?

A: I am very excited about these findings, along with other work that we are doing on this topic. Our results send a very important public health message that doing absolutely nothing — depriving oneself from any exercise — is associated with the development of a serious disease, and women who are diagnosed with this form of disease are more likely to die of ovarian cancer. Our message is that you have to do some form of exercise. Women who are physically inactive need to be aware of the 34% to 54% greater likelihood of being diagnosed with ovarian cancer.

Q: Do other factors increase the effect of physical inactivity on ovarian cancer risk?

A: Ours is the only study that found a modifiable risk factor for ovarian cancer in all different histological subtypes. We recognize that serous ovarian cancer, the most common subtype, is different from clear cell ovarian cancer. Previous studies that focused on modifiable risk factors — such as obesity or smoking — may have found an association for one subtype but not another. In our study, the findings persisted across all histological subtypes. Obesity was not associated with an increased risk for the most common subtype of ovarian cancer. The public health message may have been that if a woman loses weight, she will not be at risk for certain rare types of ovarian cancer. Now, we can say that if you do not exercise, the risk for any subtype of ovarian cancer is increased.

Q: Were you surprised by any of the results?

A: We were not. We hypothesized that physical inactivity would be bad for etiology and prognosis, and this is exactly what we found.

Q: What are the potential explanations for the association between physical inactivity and ovarian cancer risk?

A: The obvious explanation is the change in body fat. Obesity or being overweight is not good for many diseases, including various cancer types and some subtypes of ovarian cancer. However, our findings are independent of BMI. We found the same associations in women of normal weight and in those who were overweight or obese, so we cannot say that obesity or being overweight explains our findings. This, again, strengthened our conclusions. Exercise has a positive influence on hormone levels, so there is a healthier hormonal environment. Exercise reduces inflammation. We have known for a long time that inflammation is associated with a number of diseases, including ovarian cancer, and exercise has a positive influence on the immune system. We recognize that a healthy immune system helps to protect us from developing cancer and many other diseases.

Q: What is next for research on this topic?

A: We plan to look into other cancers. Researchers at Roswell Park just published a paper indicating that physical inactivity is associated with increased risk for cervical cancer. We have submitted papers looking at physical inactivity in head and neck, bladder and kidney cancers. We also are working on two papers that show physical inactivity is associated with increased risk for lung cancer and lymphoma. Along with my colleagues, I am beginning to work on studies examining physical inactivity and cancer survival where we found that patients who are physically inactive are more likely to die of lung cancer and breast cancer.

Q: What should p hysicians tell their patients about exercise as a prevent ive measure for ovarian cancer?

A : I am excited about this work because there is a lot of potential for intervention. I would tell physicians to impress upon their patients the importance of exercise. People need to incorporate some type of physical activity into their daily activities. This could include taking the stairs instead of the elevator, or parking their car far away at the supermarket. I have a very sedentary job. I occasionally take a break and walk up a flight of stairs so I do not sit all day. There are many physical activity recommendations from different societies. There are so many that they may be overwhelming or become confusing, so people may opt out of exercise or physical activity. Our message is that doing nothing is not OK. It does not have to be a triathlon or half-marathon, but anything helps. – by Jennifer Southall

F or more information:

Kirsten Moysich, PhD, MS, can be reached at Roswell Park Cancer Institute, Elm and Carlton streets, Buffalo, NY 14263; email: kirsten.moysich@roswellpark.org.

Reference s :

Cannioto RA, et al. Br J Cancer. 2016; doi:10.1038/bjc.2016.153.

Cannioto RA, et al. Cancer Epidemiol Biomarkers Prev. 2016; doi:10.1158/1055-9965.EPI-15-1330.

Disclosure: Moysich reports no relevant financial disclosures. Please see the full studies for lists of the other researchers’ relevant financial disclosures.