(NaturalNews) Here's another case of a so-called "wonder drug" heavily promoted by Big Pharma having a darker side than anyone knew. It turns out aromatase inhibitors (sold under the names Femara, Aromasin, and Arimidex), widely prescribed to huge numbers of women who've been diagnosed with estrogen receptor-positive breast cancer, could be so toxic in the body they do nothing to prolong life -- and might even shorten it.
Based on the findings of several studies, most doctors now recommend one of the aromatase inhibitor (AIs) after women with estrogen-positive breast cancer have initial treatment with surgery and often chemotherapy and radiation therapy. An AI medication has been considered a better choice than the other anti-estrogen treatment, tamoxifen, because AIs have been thought to have more benefits and fewer serious side effects.
However, research just published in the Journal of the National Cancer Institute
concludes that the toxic impact of aromatase inhibitors apparently explains why breast cancer patients taking AIs don't live any longer than women taking tamoxifen. Bottom line: the study suggests that even if AIs slow down or halt the growth of estrogen driven breast cancer, women may lose their lives not to a malignancy -- but to the negative impact the drugs have on their bodies.
AIs block the enzyme aromatase, which turns the hormone androgen into small amounts of estrogen in the body. So they reduce the amount of estrogen available that can stimulate the growth of estrogen-driven breast cancer
cells. This class of drugs doesn't halt ovaries from making estrogen, so AIs are only used in post-menopausal women. The medications are normally prescribed as an alternative to tamoxifen or after earlier treatment with tamoxifen (which often has intolerable side effects).
Overall, AI therapy alone is associated with a reduction in breast cancer recurrence -- but doesn't result in women living any longer. What's more, the drugs have been found to produce a host of concerning adverse toxic
effects on the body. And it's this toxicity that may explain the lack of overall survival benefit in postmenopausal breast cancer patients, according to researchers Eitan Amir, of the Division of Medical Oncology and Hematology at Princess Margaret Hospital in Toronto, Ontario, and colleagues.
The research team conducted a systematic review of all randomized trials which compared AIs and tamoxifen in postmenopausal women. Using results from seven trials involving 30,023 breast cancer
patients, the scientists performed a meta-analysis of the data. The results showed that, compared to tamoxifen, longer use of AIs was associated with more heart disease and bone fractures. However, tamoxifen users had higher rates of blood clots and cancer of the womb. There were no differences in the risk of stroke or other types of cancer. Overall there was no survival benefit to AIs, even though the drugs
seem to have a positive effect on breast cancer recurrence.
The researchers concluded that the toxicity of AIs was most likely behind the drugs failure to prolong life. Using tamoxifen first and then switching to AIs for 2 to 3 years was associated with a lower risk of death unrelated to breast cancer compared to the use of either AIs or tamoxifen alone. The scientists speculate that this is because switching between the two drugs lowers the toxicity of AIs in the body.
In an accompanying editorial, Nancy E. Davidson, M.D., Shannon Puhalla, M.D., and Rachel C. Jankowitz, M.D., of the UPMC Cancer Center at Magee-Womens Hospital, concluded that doctors should "..choose initial endocrine therapy for the individual patient with careful attention to the risk of breast cancer recurrence, the risk of toxicity, and comorbidities."