Complementary Treatments Highlighted at Recent Meeting

The addition of the sleep hormone melatonin can boost the effectiveness of tamoxifen and help reverse tamoxifen (Nolvadex) resistance in the treatment of breast cancer, reported David E. Blask, MD, PhD, at a meeting on Comprehensive Cancer Care: Integrating Complementary and Alternative Therapies. Melatonin was one of several experimental approaches to breast cancer described at the meeting.

Studies on Melatonin and Breast Cancer

According to Dr. Blask, who is senior research scientist at the Bassett Research Institute of Mary Imogene Bassett Hospital in Cooperstown, New York, laboratory experiments have shown that melatonin shares several links with breast cancer. One link is that nighttime production of melatonin in women with breast cancer is severely blunted, and the degree of blunting correlates with the size of the tumor, as well as its estrogen receptor (ER) status.

Another link is that when ER positive breast cancer cells are exposed in the laboratory to physiologic levels of melatonin, their growth is inhibited substantially compared to other breast cancer cells. Melatonin and tamoxifen produced a greater effect against breast cancer cells than either alone. In addition, the pretreatment of breast cancer cells with melatonin made them more sensitive to tamoxifen.

In a small study of breast cancer patients (half ER positive and half ER negative) who had become resistant to tamoxifen, melatonin was given alone for 1 week and tamoxifen was resumed together with the sleep hormone for up to 1 year or until tumor progression. Of the group, eight (57%) experienced stabilized disease for a median of 4 months, four (29%) experienced partial regression of tumor, and three (14%) experienced progression of disease.

In another study of heavily pretreated patients with metastatic, ER-negative breast cancer, 5 (31%) of 21 patients who received tamoxifen alone experienced no improvement. Of the 19 who received tamoxifen and melatonin (as in the study described above), 12 extended their expected survival for 1 year.

Coenzyme Q10 Also Under Study

Another naturally occurring substance, co-enzyme Q10 (CoQ-10), is also under scrutiny as a breast cancer treatment. Richard A. Willis, PhD, professor in the Department of Human Ecology and acting director of biomedical research at the University of Texas at Austin, reported that some cancer patients are more likely to have low levels of Co-Q10 than other people.

In an open trial in which antioxidants, essential fatty acids, and 90 mg of Co-Q10 were given for 18 months to 32 breast cancer patients who had positive axillary lymph nodes, lymphocyte and natural killer cell counts were significantly increased. Six patients experienced partial regression of their tumor; all patients remained alive after 18 months.

When the trial was extended by another 6 months with doses increased as deemed appropriate, three more patients experienced partial tumor regression, Dr. Willis said. However, patients were receiving other treatments, too, such as chemotherapy and radiation “so to say it’s the CoQ-10 is pushing the evidence too far.” However, two studies from Italy and Florida reported in May found that the approach increased survival.

Soy Products as Preventives

Stephen Barnes, PhD, reported on the use of soy products as breast cancer preventives. He said that consumption of these foods during the neonatal and prepubertal periods decreases proliferating breast cells’ susceptibility to estrogens— in effect, providing the same protection as the 17-beta-estradiol present during pregnancy.

In laboratory studies, genistein—one of the phytoestrogens present in soy—reduces incidence of tumors when fed to dimethylbenzantracene (DMBA)-treated rats. This and other research “suggests that early-life exposure to these compounds is very important in later development of cancer,” Dr. Barnes said.