5 Years of Tamoxifen Good, 10 Years Better?

I can tell you right now, that if the study on Tamoxifen that just came out in the Lancet is correct, sales of antidepressants to breast cancer survivors will soar. Tamoxifen is a well-studied drug that helps reduce the risk of recurrence for estrogen-receptor positive breast cancer. The standard of care has long been a daily dose for 5 years following primary cancer treatment. Both male and female breast cancer patients have taken Tamoxifen to lower the odds of cancer's return by 50% and many patients are willing to put up with the side effects to get those odds.

But many of those patients also take an antidepressant to help moderate the hot flashes, low libido, vaginal dryness and osteoporosis that the estrogen suppressor can cause. Even with a little Effexor to help ease the blues and the other side effects, many women quit taking Tamoxifen before their 5 years are up - citing frustration, ongoing discomfort, and problems with sexual function, to name a few.

So when the study came out showing that 10 years of Tamoxifen is even more effective than the standard 5 years, I felt like taking an extra dose of "happy pills" myself. Full disclosure: I took the drug for 2 years and then begged my oncologist to let me switch to Aromasin, which had milder side effects. I am not a full-fledged Tamoxi-Babe, I caved.

The study everybody's talking about involved more than six thousand women with early stage estrogen-sensitive breast cancer. Women all over the world who had already taken Tamoxifen for 5 years were divided into two groups - half of them stopped the drug, while the other half continued for another 5 years.

Results showed a 3.7% reduction in breast cancer recurrence when the drug was taken for 10 years. This benefit came with a slight rise in risk for endometrial cancer - one possible side effect of Tamoxifen.

AstraZeneca makes Nolvadex - one brand name for Tamoxifen, and they provided some of the funding for this study.

Naturally they would not mind providing twice as much of this drug for us as they do now. Nor would the makers of many fine antidepressants protest if they were asked to produce double the amount of pills for breast cancer patients and their long-suffering spouses and supporters. But perhaps that is beside the point.

I'll admit that I haven't read the entire study, so I don't know if the research addresses the issue of whether or not the patients were tested for Tamoxifen resistance. This drug helps many, but it does not benefit each and every patient. It is most effective for pre-menopausal women, but it also interferes with fertility. For some young female patients who want to get on with family planning, the prospect of 5 or 10 years of an antiestrogen drug is unappealing, to say the least. Some women may start on Tamoxifen while they are still fertile, but due to the effects of chemotherapy, hormone therapy, and age, find themselves in early menopause. These women change to aromatase inhibitors (as I did) and would not need to continue with Tamoxifen in that case.

So please don't lay in a lifetime supply of Tamoxifen if you have breast cancer - chances are that you will wind up using a different drug over time, or a new study will come out reporting somewhat different results. What we really need - and want - is effective prevention! Until that comes, we'll work with the wonder drugs that we have for now.

Source: Long-term effects of continuing adjuvant tamoxifen to 10 years versus stopping at 5 years after diagnosis of oestrogen receptor-positive breast cancer: ATLAS, a randomised trial. Published online December 5, 2012 in the Lancet. First author: Christina Davies, MBChB, University of Oxford, United Kingdom.

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