Herbal hope in breast cancer battle

Published on Wednesday 2 November 2005 00:04

EVENING primrose oil may prove to be a powerful weapon against aggressive breast cancer, scientists have revealed.

In laboratory tests, a substance found in the oil not only suppressed an important breast cancer gene but also amplified the effects of a drug used in advanced stages of the disease.

Thousands of women in the UK take evening primrose oil to alleviate menstrual symptoms. But new findings suggest one of its active ingredients may also combat some of the most serious cases of breast cancer.

A compound in the oil called gamma-linolenic acid (GLA) was found to inhibit the action of a gene responsible for about 30 per cent of breast cancers.

Patients with the mutant Her-2/neu oncogene generally have aggressive tumours and a poor prognosis.

GLA reduced the levels of protein made by the gene which promotes tumour growth.

It also caused a 30- to 40-fold increase in the response of breast cancer cells to Herceptin, a drug given to women once the disease has metastasised, or spread to other parts of the body. GLA increased levels of programmed cell death, or apoptosis, in cells also exposed to Herceptin.

Research leader Professor Ruth Lupu, of Northwestern University, in Evanston, Illinois, said: "In our tests, treating the cancer cell lines with both GLA and Herceptin led to a synergistic increase in apoptosis and reduced cancer growth.

"Therefore, although further studies are necessary before GLA can enter clinical trials, these findings may reveal a previously unrecognised way of influencing the poor outcome of Her-2/neu-positive cancer patients."

Both GLA and Herceptin act on the gene, but they have different effects, said the scientists whose research appears in the Journal of the National Cancer Institute.

Herceptin neutralises molecules of the gene protein found on the surface of cancer cells. GLA, on the other hand, interferes with machinery that produces more of the protein.

"Results of the study reveal a valuable means by which an inexpensive herbal medicine might regulate breast cancer cell growth," said Prof Lupu.

In the tests, GLA did not appear to affect normal cells.

Earlier research at Northwestern University has shown that GLA sensitises breast cancer tumours to other chemotherapy drugs, such as Taxol, Taxotere and Navelbine. It also enhances anti-oestrogen drugs such as tamoxifen and Faslodex.

Other herbal sources of GLA besides evening primrose oil include borage oil and black current seed oil.

Dr Sarah Rawlings, of the charity Breakthrough Breast Cancer, said: "These early findings are interesting. However, this study was carried out in breast cancer cells, and much more research is needed to discover what effect GLA will have in patients with breast cancer.

"This research does not suggest that women with breast cancer should routinely take evening primrose oil, and any woman with questions about treatment should discuss them with her doctor."