According to an article published in Obstetrical and Gynecological Survey, five-year results indicate that side effects are similar for Nolvadex® (tamoxifen) and Evista® (raloxifene) when used to prevent breast cancer in postmenopausal women at a high risk of developing the disease.
Breast cancer causes roughly 40,000 deaths annually in the U.S. alone. The majority of women with breast cancer have cancer that is estrogen receptor-positive (ER-positive). This type of breast cancer is stimulated to grow by the female hormones estrogen and/or progesterone.
Some postmenopausal women at a high risk of developing breast cancer can be treated with the anti-estrogen agent Nolvadex. In high-risk women Nolvadex reduces the risk of breast cancer by approximately 50%. This reduced risk of breast cancer, however, is accompanied by an increased risk of conditions such as endometrial (uterine) cancer and blood clots.
Evista is an agent that also reduces the stimulatory effects of estrogen on cancer growth. It is approved for the prevention and treatment of osteoporosis. However, because it reduces estrogen’s effects on cells, researchers speculated that it may also be used as a preventive or therapeutic agent for ER-positive breast cancer.
Researchers conducted a clinical trial, referred to as the STAR trial (The NSABP Study of Tamoxifen and Raloxifen [STAR] P-2 Trial), to directly compare Evista to Nolvadex in the prevention of breast cancer in women considered at high risk of developing the disease. Results from the study indicated that both agents provided similar protection against development of breast cancer among these women.
Side effects from Evista and Nolvadex were also reported from the STAR P-2 trial at nearly four years of follow-up. Researchers involved in the trial now report side effects of both agents at a follow-up of five years. Patient-reported symptoms and quality-of-life measurements were completed during treatment with either Evista or Nolvadex and every six months thereafter for five years.
- Quality-of-life scores worsened modestly in both groups of patients.
- Evista was associated with more muscle and bone side effects and with weight gain.
- Nolvadex was associated with more nerve and muscle side effects (vasomotor), more leg cramps, decreased bladder control, and more gynecological complications.
- Nolvadex was associated with better sexual function than Evista.
- Mental health issues were similar in both groups.
- The differences in the symptoms between these two groups were reportedly small.
The researchers concluded that at five years of follow-up, treatment with either Evista or Nolvadex to reduce the risk of breast cancer does not produce significant differences in overall quality of life. Although there were some differences in side effects between the two agents, these differences remained small.
Patients at a high risk of developing breast cancer may wish to speak with their physician regarding their individual risks and benefits of different preventive strategies.
Reference: Land SR, Wickerham DL, Constantino JP, et al. Patient-reported symptoms and quality of life during treatment with tamoxifen or raloxifen for breast cancer prevention. The NSABP study of tamoxifen and raloxifen (STAR) P-2 Trial. Obstetrical and Gynecological Survey. 2006;61:651-653.