Changes in bone mineral density during 5years of adjuvant treatment in premenopausal breast cancer patients.

Abstract

Adjuvant treatment for breast cancer in postmenopausal women is a risk factor for bone loss. However, the association between bone mineral density (BMD) changes in premenopausal breast cancer patients and various adjuvant treatment regimens is not well characterized. In this study, we evaluated the changes in BMD according to adjuvant treatment in premenopausal women with breast cancer. Between 2006 and 2010, BMD data of 910 premenopausal women with breast cancer before operation and 1, 2, 3.5, and 5years post-operation were retrospectively analyzed. The patients were divided according to the type of treatment: observation (O), tamoxifen (T), chemotherapy (C), C followed by T (C → T), and gonadotropin-releasing hormone (GnRH) agonist with T (G + T). After 5years of follow-up, BMD changes were similar between the T and O groups (all p > 0.05). Within 1year of treatment, the C group showed the most significant BMD loss. The C → T and G + T groups showed more significant BMD loss in the lumbar spine and femur than the O and T groups (both p < 0.001, both). After 1year of treatment, BMD loss in the lumbar spine was significantly greater in the C → T and G + T groups than in the T group; this tendency was maintained for 5years of treatment (all p < 0.005). Premenopausal women who received adjuvant treatment which induced menopause showed significant bone loss which lasted for 5years. Although no significant difference was observed between the O and T groups, tamoxifen treatment during chemotherapy or GnRH agonist treatment might prevent bone loss.