Nightly Fast Duration May Influence Breast Cancer Recurrence

Prolonged nightly fasting may help to reduce breast cancer recurrence

medwireNews: US researchers suggest that women might be able to reduce their risk of recurrent breast cancer by fasting overnight for at least 13 hours.

Ruth Patterson, from San Diego Moores Cancer Center in La Jolla, California, and co-investigators collated data for 2413 participants of the Women’s Healthy Eating and Living study from time-stamped food diaries and medical records detailing age, disease stage and comorbidity.

As reported in JAMA Oncology, the nightly fast was calculated by subtracting the time between the first and last meal of the day from 24 hours.

The average nightly fast was 12.5 hours. After adjusting for a raft of confounding factors, women in the bottom two tertiles for fast length, defined as less than 13 hours, were 1.36 times more likely to experience breast cancer recurrence than those in the top tertile who fasted for 13 hours or longer.

The authors note that a nightly fast of less than 13 hours did not increase the risk of breast cancer-specific mortality or all-cause mortality compared with a longer fast. Nor were number of eating episodes per day or eating after 8 pm associated with the risk of breast cancer recurrence or mortality.

Nevertheless, multivariate analysis confirmed that each 2-hour increase in the length of the nightly fast was associated with a significant 0.37 mmol/mol reduction in haemoglobin A1c level and a significant 0.2 hours of sleep more per night.

There was no significant correlation between nightly fast length and body mass index or C-reactive protein concentration, although both measures were significantly higher in women who ate after 8 pm than those whose last meal was earlier.

The authors note that several studies have suggested there may be a link between breast cancer and diabetes or hyperglycaemia, and that other research points to links between food consumption late at night, circadian rhythm disruption, sleep patterns and cancer risk.

They therefore conclude: “Prolonging the length of the nightly fasting interval may be a simple, nonpharmacologic strategy for reducing the risk of breast cancer recurrence.
“Improvements in glucoregulation and sleep may be mechanisms linking nightly fasting with breast cancer prognosis.”

Marinac CR, Nelson SH, Breen CI, et al. Prolonged nightly fasting and breast cancer prognosis. JAMA Oncol 2016; Advance online publication 31 March. doi:10.1001/jamaoncol.2016.0164

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