Controlling diet may help prevent spread of deadly breast cancer: study

Limiting the intake of foods rich in asparagine such as dairy, beef, poultry and eggs may potentially help prevent the spread of a deadly type of breast cancer, researchers including one of Indian origin claim.

Researchers found that by limiting asparagine in laboratory mice with triple-negative breast cancer, they could dramatically reduce the ability of the cancer to travel to distant sites in the body.

In the study, published in the journal Nature, the team used dietary restrictions to limit asparagine among other techniques.

Foods rich in asparagine include dairy, whey, beef, poultry, eggs, fish, seafood, asparagus, potatoes, legumes, nuts, seeds, soy and whole grains. Foods low in asparagine include most fruits and vegetables.

"Our study adds to a growing body of evidence that suggests diet can influence the course of the disease," said Simon Knott, associate director at Cedars-Sinai Medical Center in the US.

If further research confirms the findings in human cells, limiting the amount of asparagine cancer patients ingest could be a potential strategy to augment existing therapies and to prevent the spread of breast cancer, Knott added.

"This study may have implications not only for breast cancer, but for many metastatic cancers," said Ravi Thadhani, vice dean, Research and Graduate Research Education, at Cedars-Sinai.

The researchers studied triple-negative breast cancer cells, which grow and spread faster than most other types of cancer cells.

It is called triple negative because it lacks receptors for the hormones estrogen and progesterone and makes little of a protein called HER2.

As a result, it resists common treatments - which target these factors and has a higher-than-average mortality rate.

The researchers discovered that the appearance of asparagine synthetase - the enzyme cells used to make asparagine - in a primary tumor was strongly associated with later cancer spread.

They also found that metastasis was greatly limited by reducing asparagine synthetase, treatment with the chemotherapy drug L-asparaginase, or dietary restriction.

When the lab mice were given food rich in asparagine, the cancer cells spread more rapidly.

"The study results are extremely suggestive that changes in diet might impact both how an individual responds to primary therapy and their chances of lethal disease spreading later in life," said Gregory J Hannon from University of Cambridge in the UK.

Investigators now are considering conducting an early- phase clinical trial in which healthy participants would consume a low-asparagine diet.

If the diet results in decreased levels of asparagine, the next scientific step would involve a clinical trial with cancer patients.

That trial likely would employ dietary restrictions as well as chemotherapy and immunotherapy, Knott said.