Improvement in the Prognosis of Japanese Breast Cancer Patients from 1946 to 2001—an Institutional Review

Background: Breast cancer has emerged as one of the most frequent malignancies among Japanese women; however, the long-term survival of Japanese breast cancer patients is uncertain. Methods: We analyzed the chronological changes in the clinical and pathological characteristics, treatment procedures and the long-term prognosis of 15 416 Japanese women with 16 217 primary breast cancers treated in the Cancer Institute Hospital in Tokyo between 1946 and 2001. Results: Our analysis revealed a chronological increase in the mean patient age, postmenopausal patients and non-invasive carcinomas. Operative procedures became less extensive, with approximately 45% of breast cancer patients in 2000–2001 receiving breast-conserving treatment. Radiotherapy to the regional lymph nodes decreased, while postoperative chemotherapy and hormonal treatments have become more frequent. The survival rate has improved steadily during the past 5 decades. The 10-year crude overall survival rate improved from 61% before 1960 to 83% in the 1990s. Conclusions: The survival rate of Japanese women with breast cancer has dramatically improved during the past 5 decades.