Avoiding food at night may reduce breast cancer recurrence

Women diagnosed with early-stage breast cancer may lower their risk of tumors coming back if they avoid eating for 13 hours or more each night, a study published Thursday said.

The findings in the Journal of the American Medical Association (JAMA) Oncology build on previous studies in rodents that showed night-time fasting could ward off high blood sugar, inflammation and weight gain, all of which may worsen cancer outcomes.

The current study is based on survey data collected from 2,413 women with early-stage breast cancer — and without diabetes — between 1995 and 2007.

The women ranged in age from 27 to 70 at diagnosis. They were followed for an average of seven years after diagnosis for any new tumors, and any deaths from breast cancer or other causes were tracked for 11 years.

Those who fasted less than 13 hours per night saw a 36 per cent higher risk of breast cancer recurrence compared to those who refrained from eating for 13 or more hours per night.

“Prolonging the overnight fasting interval may be a simple, non-pharmacological strategy for reducing a person’s risk of breast cancer recurrence and even other cancers,” said lead author Catherine Marinac, a doctoral candidate at the University of California San Diego Moores Cancer Center.

“Previous research has focused on what to eat for cancer prevention, but when we eat may also matter because it appears to affect metabolic health.”

Patients who did not eat at night for longer periods also slept better and showed more normal glucose metabolism than those who snacked before bed. However, the benefits of night-time fasting were not as apparent when it came to the study’s analysis of the risk of dying from breast cancer.

Those who fasted less than 13 hours per night appeared to face a higher risk of dying from breast cancer, but researchers determined the difference was not statistically significant.

Since the study relied on self-reported dietary data, authors said more rigorous research should be done, using randomized controlled trials, to better understand the health benefits of avoiding food at night.

“If future trials confirm that habitual prolonged nightly fasting improves metabolic health, this would be an important discovery in prevention that could reduce the risk of cancers, type two diabetes, and cardiovascular disease,” said senior author Ruth Patterson, leader of the cancer prevention program at Moores Cancer Center.