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by Dr. C.H. Weaver M.D. 5/2019

Early research suggests that a vegan or vegetarian diet low in the amino acid methionine may help improve treatment of triple-negative breast cancers. These findings were reported in the journal Clinical Cancer Research.

The majority of breast cancers are hormone receptor-positive, meaning that the cancer cells are stimulated to grow from exposure to the female hormones estrogen and/or progesterone. Other breast cancers are referred to as HER2-positive, which means that they overexpress the human epidermal growth factor receptor 2, a biologic pathway that is involved in replication and growth of a cell.

Breast cancers, on the other hand, that are not stimulated to grow from exposure to estrogen or progesterone and do not overexpress HER2 (HER2 negative) are called triple-negative breast cancers. Triple-negative breast cancers tend to be more aggressive than other breast cancers and have fewer treatment options because hormonal therapies that target hormone receptors or HER2 are ineffective.

Because patients with triple-negative breast cancer have limited treatment options, finding effective therapies is an important area of research. In a recent study, researchers tested a dietary approach to improving treatment of triple-negative breast cancer. Specifically, they evaluated whether patients who consumed lower levels of a nutrient known as methionine had a better response to therapies targeted against triple-negative disease.

Methionine is an essential amino acid, a building block of proteins, which is high in meat, fish, some legumes, and nuts, but low in fruits and vegetables. It appears that some cancers get weaker when they don’t get enough methionine. In particular, methionine appears to cause cancer cells to increase the amount of a receptor on their surface called TRAIL-R2. As a result, drugs that target TRAIL-R2 can more easily find the cancer cells and bind to them, which kills the cancer cells.

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To test how effectively methionine deficiency could help in the treatment of triple-negative breast cancer, the researchers performed a laboratory test in which they used triple-negative breast cancer cells that were either exposed to methionine or deprived of the amino acid. They studied how much TRAIL-R2 cells from each group produced on their surface and used a drug targeted against TRAIL-R2 (lexatumumab) on the cells.

Cancer cells that were deprived of methionine and had the highest expression of TRAIL-R2 were the most vulnerable to lexatumumab. In other words, the drug was most effective in cells that weren’t exposed to methionine.

Based on these findings, it’s reasonable to think that a diet low in methionine may make targeted treatment for triple-negative breast cancer more effective. Methionine restriction may be worth exploring in future clinical trials.


Strekalova E, Malin D, Good DM, Cryns VL. Methionine Deprivation Induces a Targetable Vulnerability in Triple-Negative Breast Cancer Cells by Enhancing TRAIL Receptor-2 Expression. Clinical Cancer Research. 2015 June 15;21(12):2780-91. doi: 10.1158/1078-0432.CCR-14-2792

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