Less sleep, frequent snoring shorten breast cancer survival

Short sleep duration and frequent snoring prior to cancer diagnosis may shorten OS among postmenopausal women with breast cancer.

Amanda I. Phipps, MPH, PhD, assistant professor of epidemiology at University of Washington, and colleagues assessed the association between sleep characteristics prior to cancer diagnosis and subsequent cancer survival among postmenopausal women who participated in the Women’s Health Initiative.

Amanda I. Phipps

The analysis included data from 21,230 Women’s Health Initiative participants, in whom a first primary invasive cancer had been diagnosed during follow-up. All women had provided information about sleep characteristics at baseline.

Phipps and colleagues used Cox regression to calculate HRs for associations between prediagnostic sleep characteristics and cancer-specific survival for all cancers, as well as individually for common malignancies. They adjusted for age, cancer site, smoking status, physical activity and other variables.

An analysis of all cancer sites combined showed no significant associations between cancer survival and any individual sleep characteristic prior to diagnosis.

However, women who reported short sleep duration — defined as 6 hours or less per night — plus frequent snoring, defined as 5 or more nights per week, achieved significantly shorter cancer-specific survival than those who slept 7 to 8 hours per night and did not snore (HR = 1.32; 95% CI, 1.14-1.54).

When researchers focused on women with breast cancer, results showed short sleep duration (HR = 1.46; 95% CI, 1.07-1.99) and frequent snoring (HR = 1.34; 95% CI, 0.98-1.85) each were associated with shorter breast cancer survival.

Women who reported both short sleep duration and frequent snoring achieved considerably shorter breast cancer survival than women who reported longer sleep duration and no snoring (HR = 2.14; 95% CI, 1.47-3.13).

Phipps spoke with HemOnc Today about these findings and their potential implications.

Question: What prompted you to assess the po tential link s between sleep duration , snoring and cancer survival?

Answer: We already know that sleep has been associated with an increased risk for several types of cancer. Our thinking was that the impact of sleep on the development of cancer probably does not stop at the time of a cancer diagnosis. Sleep has so many far-reaching effects on so many health outcomes, it seemed plausible to us that poor sleep could really have an impact on the ability of a person to survive their cancer.

Q: What do you consider the key finding from your study?

A: Sleep is important, and it seems to be especially important among women with breast cancer. Among these women, short sleep duration and frequent snoring has an effect on the death rate from their disease. Although we already know there are a number of reasons to promote healthy sleep, our study offers one more reason for people to get the sleep their body needs.

Q: Did any of the results surprise you?

A: We had not entirely anticipated the results we saw with respect to snoring. This has not been discussed thoroughly in previously published literature, and we plan to study it further.

Q: Why do you suspect that breast cancer specifically is affected by lack of sleep and snoring?

A: This is the big question that we are unable to answer from this particular study. In this study of postmenopausal women, breast cancer is the malignancy we see most frequently. It may just be that we had a large enough sample of women to really see an effect and that other cancer types were not as common, so it was harder for us to identify an association. We do not have a good biological explanation for why it affected breast cancer specifically. We want to look into this with future research.

Q: What should physicians tell their patients about the importance of their sleep patterns?

A: The general sleep recommendation for patients with breast cancer, other cancer types and even for people without cancer is for adults to receive 7 to 8 hours of sleep per night. This reflects the far-reaching impact of sleep on a variety of health outcomes, and our results are consistent with that recommendation.

Q: What will your future research entail?

A: We are launching a new study to assess sleep apnea and cancer survival. In our study, we were able to look at snoring, which could be an indication of sleep apnea in a number of individuals. Sleep apnea is a growing epidemic, so we are looking at the possible association with cancer survival. – by Jennifer Southall

For more information:

Amanda I. Phipps , MPH, PhD , can be reached at University of Washington, 1959 N.E. Pacific St., Box 357236, Seattle, WA 98195; email: aiphipps@u.washington.edu.

Reference:

Phipps AI, et al. J Clin Sleep Med. 2016;12:495-503.

Disclosure: Phipps reports no relevant financial disclosures.