[Bone and calcium metabolism associated with malignancy. Clinical Characteristics and Treatment of Cancer Treatment Induced Bone Loss(CTIBL)in Breast Cancer.]

Abstract

Breast cancer is a typical hormone-dependent tumor and at the time of diagnosis more than 60% of breast cancers are positive for estrogen receptors and estrogen(E)is required for proliferation. Since breast cancer is a tumor easily to cause micrometastasis, adjuvant hormonal therapy(HT)for 5 to 10 years after surgery that suppresses the action of estrogen actively prevents recurrence is very popular. However, HT with aromatase inhibitor(AI)for postoperative postmenopausal breast cancer markedly reduces the E concentration in the body, leading to significant bone loss and fracture as known as aromatase inhibitor-induced bone loss(AIBL), a typical example of CTIBL. Under these circumstances, the usefulness of bone modifying agents as a supportive therapy to increase bone density and decrease fracture rate without interrupting the treatment of breast cancer became clear, mainly in Europe and the United States. And recently, our study revealed even in Japanese breast cancer patients denosumab injection every 6 months showed significant increase in bone density. The number of women suffering from breast cancer in Japan reaches approximately 90,000 per year, a considerable number is estimated as a preliminary group of CTIBL, so early appropriate measures are desired.