Current Status and Controversial Issues concerning Endocrine Therapy for Patients with Recurrent Breast Cancer in Japan.

BACKGROUND: Four different endocrine therapeutic agents have been used in Japan since 1996. However, a consensus regarding proper use of these agents has notyet been established. Therefore, a questionaire survey of Japanese breast cancer authorities on endocrine therapy and a multi-institute survey to investigate the efficacy of a single first-line endocrine therapy for recurrent breast cancerwere conducted. MATERIALS AND PATIENTS: A total of 279 questionaires were sent to the Councilors of the Japanese Breast Cancer Society. The clinico-pathological data of 77 breast cancer patients who underwent a single first-line endocrine therapy were collected from five institutes. RESULTS: The response rate to this questionaire survey was 67.4%. The resultsshow that many authorities consider that: 1) both ER and PgR in primary tumors should be measured, 2) patient age, the disease-free interval and postoperative adjuvant therapy do not provide enough information for the selection of endocrine therapies, 3) antiestrogen and LH-RH agonists should be used as first-line endocrine therapies, 4) combined endocrine therapies, such as an antiestrogen plus an LH-RH agonist, should be used, 5) the optimal sequence of use of endocrine therapeutic agents is most controversial. The objective response rate to first-line endocrine therapies was 40.3% and the duration of response was over 15 months.The objective response rate to second-line endocrine therapies was 42.1%. A multiple regression analysis of predictive factors for the efficacy of first-line endocrine therapies indicated two factors, the disease-free interval and dominantsite of metastasis, to be significant. Conclusions: This questionaire survey suggests that clinical trials to investigate the optimal sequence of use of endocrine therapies and to clarify the usefulness of combined endocrine therapies should be conducted. Single first- or second-line endocrine therapies for recurrent breast cancer are effective and should be carried out by general clinicians.