Calorie restriction could be a non-toxic way of slowing down spread of breast cancer, a study said.
The triple negative subtype of breast cancer - one of the most aggressive forms - is less likely to spread, or metastasise, to new sites in the body when mice were fed a restricted diet.
"Calorie restriction promotes epigenetic changes in the breast tissue that keep the extracellular matrix strong," said Nicole Simone, an associate professor at Thomas Jefferson University in the US.
"A strong matrix creates a sort of cage around the tumour, making it more difficult for cancer cells to escape and spread to new sites in the body," Simone noted.
When mouse models of triple negative cancer were fed 30 percent less than what they ate when given free access to food, the cancer cells decreased their production of microRNAs 17 and 20 (miR 17/20).
This group of miRs is often increased in triple negative cancers that metastasise.
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Breast cancer patients are often treated with hormonal therapy to block tumour growth, and steroids to counteract the side effects of chemotherapy.
However, both treatments can cause a patient to have altered metabolism which can lead to weight gain.
Recent studies have shown that too much weight makes standard treatments for breast cancer less effective, and those who gain weight during treatment have worse cancer outcomes.
"That is why it is important to look at metabolism when treating women with cancer," Simone added.
If calorie restriction is as effective in women as it is in animal models, then it would likely change the expression patterns of a large set of genes, hitting multiple targets at once without toxicity.
The study appeared in the journal Breast Cancer Research and Treatment.