Study finds it reduces the risk of disease spreading to other organs

A low calorie diet may help prevent the spread of one of the deadliest forms of breast cancer.

Scientists believe that radiotherapy used to treat tumours would be more effective if women were eating a third less than usual.

In the US study a low calorie diet appeared to prevent the spread of triple negative breast cancer, a particularly aggressive form of the disease.

It affects around a fifth of all women with breast cancer – about 10,000 new cases a year – and is more common in the under-40s.

It spreads very quickly, with tumours often returning after treatment.

One theory is that dieting may decrease chance of cancer spreading by strengthening the tissue surrounding the tumour.

Many breast cancer patients are treated with hormonal therapy to block tumour growth and steroids to counteract the side effects of chemotherapy.

But both treatments can alter the metabolism – which in turn, can trigger weight gain, with the average woman gaining 10lb in the first year of treatment.

Previous studies have shown that being overweight makes breast cancer treatment less effective, and those who gain weight during treatment have worse cancer outcomes.

‘That’s why it’s important to look at metabolism when treating women with cancer,’ said study leader Dr Nicole Simone, from the department of Radiation Oncology at Thomas Jefferson University, Philadelphia.

The study involved feeding one group of mice a third less than another group.
‘We found that the diet turned on a programme that protected mice from metastatic disease,’ explained Dr Simone.

The study, published in the journal Breast Cancer Research and Treatment, found that in the dieting mice, cancer cells decreased their production of microRNAs 17 and 20 (miR 17/20).

These are molecules that play a vital role in influencing the pathways responsible for many disease processes.

Researchers have found that in triple negative cancers that spread, this group of microRNAs is often increased.

Dr Simone has previously discovered that calorie restriction boosts the effectiveness of radiation therapy.

The new study set out to examine which molecular pathways were involved in this effect.

The researchers found that the microRNAs decreased the most when mice were treated with both radiation and calorie restriction.

This decrease in turn increased the production of proteins involved in strengthening the tissue surrounding the tumour.

Dr Simone said: ‘Calorie restriction promotes epigenetic changes in the breast tissue that keep the extracellular matrix strong.

This is a scaffold that provides support to the cells.

Dr Simone added: ‘A strong matrix creates a sort of cage around the tumor, making it more difficult for cancer cells to escape and spread to new sites in the body.’

The findings should help pave the way for new drugs to treat cancer. In theory, a drug that decreased miR 17 could have the same effect on the extracellular matrix as calorie restriction.

However, the researchers say that targeting a single molecular pathway, such as the miR17, is unlikely to be as effective as calorie restriction.

Written by Anna Hodgekiss and Sophie Borland for The Daily Mail, May 27, 2014.

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