Thinking About Tamoxifen, by Helen Schiff Newly diagnosed women who are often very fearful about taking tamoxifen and are in fact deciding not to take it. I think it is important to understand where this fear is coming from and how to alleviate it. 1) Women read on line, hear from the media, or look at the label and see this long list of side effects: uterine cancer, uterine sarcoma, blood clots, pulmonary embolism, stroke, cataracts to name the serious and life threatening ones; hot flashes, vaginal discharge, depression, etc., to name some of the quality of life ones. That would make anyone fearful. I think it is important to point out that a label for almost any drug would have just as scary, if not more scary, a list. For example: developing a blood clot is also a risk for oral contraceptives; in the case of uterine sarcoma, only 159 cases have been identified worldwide in over 30 years of tamoxifen use by millions of women, 4 million this year alone in the U.S. 2) Most drugs have risks; in making a decision to take a drug you have to decide whether the risks are worth the benefits. Mathematically, if you add up the serious and life-threatening side effects of tamoxifen and compare these to the benefit of tamoxifen in local and distant recurrences, the OVERWHELMING MAJORITY of ER+ women with invasive breast will have an overall favorable risk/benefit ratio. Just look at the numbers. About 65% of all women with breast cancer will be alive in 25 years (if they haven’t died of something else). This means that 35%, a little more than 1 in 3 women, will eventually die of their breast cancer. Yet all the serious and life-threatening side effects of tamoxifen add up to less than 1%. And the actual number of deaths caused by these side effects are a small fraction of the 1%. (See #4 about how to assess individual risk since the 1 in 3 figure applies to the whole population of women with breast cancer and not to the individual.) 3) You may ask why I say the overwhelming majority of ER+ women will benefit from tamoxifen, BUT NOT ALL. Some women may have other conditions that will make the risks of tamoxifen greater than the benefits. For example, a seventy-five year old woman with a small stage 1 breast cancer who already had a stroke or a blood clot, might be at greater risk of suffering another stroke than of having a local or distant recurrence. Her risk is low both because her tumor is small, and because she has fewer years to live than say a 40 year old woman with the same size tumor who doesn’t have clotting problems. 4) When thinking about risks it is important to remember that a woman with an early stage 1 cancer has a much smaller risk of developing metastatic disease than a woman with a larger tumor. So her decision not to take tamoxifen, or to go off it because it is negatively affecting her quality of life, is not as much of a gamble. Women with stage 3 breast cancer will have a higher risk than the average, and women with stage 1 breast cancer will have a much lower risk than the average. And it is important to realize that the higher your risk of dying of breast cancer, the greater the benefit of tamoxifen. An estimated 70-75% of node negative women are cured by surgery alone, so tamoxifen is of no benefit to them. Unfortunately, it isn’t known who is cured by surgery and who isn’t, so most doctors will recommend tamoxifen to all women who are ER+. Another way of looking at this is that it helps 1 in 5 of the node negative women who were going to recur. Over more than a 10 year period, node negative women on tamoxifen will increase their chances of survival by 5%, from 73.3% (women not on tamoxifen) to 78.9%. Node positive women on tamoxifen will increase their chances of survival by over 10%, from 50.1% to 61.4%. In addition to extending survival, tamoxifen also reduces the risk of local recurrence which is an extremely important benefit for most women. A local recurrence, though not life-threatening, can be psychologically devastating and can mean the loss of a breast. The disease free survival (which means not having a distant OR local recurrence) for node negative women on tamoxifen is 79.2% vs. 64.3% for women not taking tamoxifen. (These figures underestimate the beneficial effect of tamoxifen by a very small amount because, of the 30,000 women in the study, about 4,000 were ER-.) 5) There can be some negative quality of life side effects from tamoxifen such as depression and hot flashes. Some women will feel that the benefit they are gaining from tamoxifen is not worth the suffering they are experiencing. As long as they are well-informed about the benefit they are giving up, that is their right. Again the higher risk a woman has of having a recurrence, the more she will lose by not taking tamoxifen. There is also very effective medication that may relieve hot flashes and depression. 6) One of the main reasons why tamoxifen has gotten a bum rap is that there has been so much opposition to using it to prevent or reduce the risk of breast cancer in healthy women who don’t have, and might never get breast cancer. 7) What most women do not understand is that tamoxifen has fewer side effects than chemotherapy. Also for women who are ER+, tamoxifen is more beneficial than chemotherapy. The side effects of tamoxifen are less in young women than in older women, especially those over 60. Also a woman who has had a hysterectomy cannot get uterine cancer. 8) Some women think that tamoxifen only works for the five years you are taking it. Clinical trials show that it continues to work for more than 10 years after you have stopped taking it. Longer term data will be available as the trials mature. 9) It is most important to convey to women that before they can make a rational decision about taking tamoxifen, they need to know what their individual risk of recurrence actually is. If they are told by their doctor that tamoxifen can reduce their risk of recurrence by 50%, they should ask, “Fifty percent of what? What is my risk of recurrence to begin with.” 10) There is a new kid on the block. Some oncologists are prescribing Arimidex instead of tamoxifen in the adjuvant setting for women with ER+ breast cancer. Unfortunately, there is only four year data on Arimidex for newly diagnosed postmenopausal women. It is not for premenopausal women. The long term side effects as well as the long term benefit will not be known for years. The four year data does show a big increase in preventing recurrences compared to tamoxifen. Also, it is unlikely that Arimidex will cause uterine cancer. It does cause blood clots, but so far the risk is lower than with tamoxifen. On the other hand, there is an increase in bone fractures so now it is being studied with Fosamax. Arimidex, unlike tamoxifen, cuts your estrogen production to almost zero, and we don’t know what that will mean in the long term. Tamoxifen just blocks the estrogen in the breast, but estrogen is still circulating in the body. It is important to tell women to ask their doctors about the pros and cons of both tamoxifen and Arimidex. Again, the long term risks of Arimidex are unknown. Helen Schiff Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.