Purpose: To examine raloxifene use among women with a history of breast cancer.
Methods: Kaiser Permanente tumor registry and membership files were used to identify women diagnosed with breast cancer after 1994 who were health plan members in 1998 or later, when raloxifene became available. Information on raloxifene treatment was obtained from computerized pharmacy records. Treatment patterns were examined and the characteristics of those who did and did not receive raloxifene were compared.
Results: Among the 17,968 women with a history of breast cancer, 711 (4.0%) had at least one prescription for raloxifene. Use among these women was more common than among similarly aged women in the health plan without a history of breast cancer, especially among those less than age 60 years. Among women with a history of breast cancer, raloxifene users were more than twice as likely as non-users to have had a bone mineral density test (60 versus 26%, p<0.0001) and, if tested, were more likely to have osteopenia or osteoporosis (80 versus 63%, p<0.0001). Compared to non-users, users had earlier stage breast cancer at diagnosis (80% versus 71% with local disease, p<0.0001). Raloxifene use was largely restricted to women whose initial breast cancer had not been treated with adjuvant tamoxifen or who had received less than 5 years of tamoxifen therapy.
Conclusion: In this setting, raloxifene use among women with a history of breast cancer is related to stage at diagnosis and bone mineral density and is rare among women who have completed a 5-year course of adjuvant tamoxifen.