TAMOXIFEN IN BREAST CANCER: WHY NOT GIVE CHEMOTHERAPY AND TAMOXIFEN TO EVERY PATIENT?
It must be kept in mind that for each patient the benefits from either chemotherapy or tamoxifen therapy must be weighed against the risks and costs. The benefit in many cases may translate into a delay in tumor recurrence, not a cure. The side effects of chemotherapy can be life threatening, and these risks are easily weighed against chemotherapy's life-prolonging effect. The side effects of tamoxifen are less common and not as life threatening, so that it is more difficult to weigh risks against benefits. Obviously, though, the life-prolonging effects are achieved with much less toxicity than those produced by chemotherapy. In patients with a tumor smaller than one centimeter, the absolute benefit from tamoxifen therapy is small—approximately 2 percent fewer tumor recurrences. Compared to the incidence of tamoxifen-induced side effects such as life-threatening thromboembolic disease (1.5 percent risk) or endometrial cancer (1.1 percent risk), the benefit from tamoxifen therapy may not be worth the risk. Furthermore, tamoxifen must be taken daily for two to five years at a cost of up to a thousand dollars per year (in the United States). The long-term side effects more than ten years after a course of tamoxifen of more than two years are also unknown.