News Release

Prolonged nightly fasting may reduce risk of breast cancer recurrence

Peer-Reviewed Publication

JAMA Network

Fasting less than 13 hours per night was associated with an increased risk for breast cancer recurrence in women with early-stage breast cancer, according to an article published online by JAMA Oncology.

Studies in rodents suggest that prolonged fasting during sleep can protect mice fed a high-fat diet against abnormal glucose metabolism, inflammation and weight gain, all of which are associated with poor cancer outcomes.

Ruth E. Patterson, Ph.D., of the University of California, San Diego, and coauthors examined whether the duration of nightly fasting can predict breast cancer prognosis.

The study included data collected from 2,413 women with early-stage breast cancer and without diabetes who were 27 to 70 at diagnosis and who participated in the Women's Healthy Eating and Living study between 1995 and 2007.

The present study looked at invasive breast cancer recurrence and new primary breast tumors during an average of 7.3 years of follow-up, as well as death from breast cancer or any cause during an average 11.4 years of surveillance.

Women in the study were an average age of 52.4 years and had an average fasting duration of 12.5 hours per night.

The authors report that a short nightly fast of fewer than 13 hours was associated with a 36 percent higher risk for breast cancer recurrence compared with fasting 13 or more hours per night. However, shorter fasting was not associated with a higher risk for death from breast cancer or from any other causes.

Other analysis indicates that each two-hour increase in nightly fasting was associated with lower hemoglobin A1c levels and a longer duration of nighttime sleeping.

The authors note their study used self-reported dietary data, which can be a limitation because it can be prone to biases.

"Our study introduces a novel dietary intervention strategy and indicates that prolonging the length of the nightly fasting interval could be a simple and feasible strategy to reduce breast cancer recurrence. In this cohort of patients with early-stage breast cancer, a longer nightly fasting interval was also associated with significantly lower concentrations of HbA1c and longer sleep duration. Given the associations of nightly fasting with glycemic control and sleep, we hypothesize that interventions to prolong the nightly fasting interval could potentially reduce the risk of type 2 diabetes, cardiovascular disease and other cancers. Thus, findings from this study have broad and significant implications for public health. Randomized trials are needed to adequately test whether prolonging the nightly fasting interval can reduce the risk of chronic disease," the authors conclude.


(JAMA Oncol. Published online March 21, 2016. doi:10.1001/jamaoncol.2016.0164. Available pre-embargo to the media at

Editor's Note: The study includes funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Media Advisory: To contact corresponding study author Ruth E. Patterson, Ph.D., call Yadira Galindo at 619-543-6163 or email

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