By Keith Roach, M.D. on
DEAR DR. ROACH: I had been on hormone replacement therapy for 20 years or so and was diagnosed with breast cancer last year. I had a lumpectomy (stage 1) and radiation (external, five days a week for 21 treatments). Now, the oncologist is saying I need to start taking tamoxifen indefinitely. I have read online that it can cause memory loss, liver injury, stroke, blood clots and/or endometrial cancer. What are the chances of any of these happening? These possibilities seem potentially worse than the original cancer spreading. -- E.H.
ANSWER: Tamoxifen for breast cancer is indeed associated with a risk of serious medical issues, but you need to consider the benefits as well.
Memory loss was seen in some studies of tamoxifen. Verbal memory was decreased in one study (by about 0.2 points on a 45-point scale), and executive function speed was reduced by about 0.2 seconds. These results were statistically significant but small.
Women with breast cancer may develop fatty liver disease on tamoxifen treatment. This rarely causes symptoms and does not seem to increase the risk of severe liver damage. The risk can be reduced by about 50% through exercise.
Because tamoxifen acts like an estrogen in some ways, the risk of blood clots and stroke is increased. It is estimated that about three women per 1000 will have a stroke due to tamoxifen. However, tamoxifen protects against heart disease. So, about three women per 1,000 will not get a heart attack who otherwise would have, making the net effect of combined stroke and heart disease almost none. However, women at high risk for blood clots should probably not take tamoxifen.
The risk of endometrial cancer in post-menopausal women after five years of tamoxifen is approximately three women per 1,000, whereas it is less than 1 woman per 1,000 for premenopausal women treated with tamoxifen.
The risks of tamoxifen are real but small, and so you must weigh them against the benefits. I don't have enough information to estimate your risk of a recurrence of breast cancer, but your oncologist does. As an example, a low-risk woman with small stage 1 cancer might have a risk of recurrence of 10%. Tamoxifen would be expected to reduce that by 30% to 40%, meaning an absolute risk reduction of 3% to 4%. For most women, the benefit in breast cancer recurrence is greater than the combined risk of stroke, blood clot, endometrial cancer and serious liver disease. Most women are on tamoxifen for five years, though some high-risk women will benefit from 10 years -- but not indefinitely.
Your oncologist should give you more-personalized risk and benefit estimates than I can give, in order to give you the best information to make your choice.
DEAR DR. ROACH: Can I take testosterone replacement if I have benign prostatic hypertrophy? -- P.T.
ANSWER: Because prostate tissue can grow with testosterone treatment, it's a reasonable question. But, in a large study comparing men who were on testosterone treatment versus an inactive placebo, there wasn't any difference in the symptoms of an enlarged prostate (among the most common symptoms are a slow urinary stream and increased urinary frequency). That's probably because the testosterone replacement just gets men back to normal levels of testosterone, not to excessively high levels.
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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.
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