Effect of screening mammography on cumulative survival of Japanese women aged 40-69 years with breast cancer.

Background: The effectiveness of screening mammography (MMG) has mainly been demonstrated by studies in western countries. This study was conducted to evaluate cumulative survival and the risk of breast cancer death among Japanese women aged 40-69 years with screening-detected and interval breast cancer divided into three groups: MMG with clinical breast examination (CBE), CBE alone, and self-detection.
Methods: By matching a list of 126,537 women (358,242 person-screenings) who participated in the Miyagi Cancer Society Screening program between 1 April 1995 and 31 December 2002 with the Miyagi Prefectural Cancer Registry, 429 MMG with CBE, 522 CBE, and 3,047 self-detected cases were included in this study. Follow-up was performed until the date of death or 31 December 2007. Survival was estimated by the Kaplan-Meier method. The Cox proportional hazards model was used to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for breast cancer death.
Results: Five-year survival for women in the MMG with CBE, CBE, and self-detection groups was 96.8, 92.7, and 86.6 %, respectively. The HR (95 % CI) for breast cancer death was 2.38 (0.72-7.94) among CBE-screened and 4.44 (1.42-13.89) among self-detected cases for women aged 40-49 years, but was 3.00 (1.63-5.50) among CBE-screened and 4.51 (2.69-7.56) among self-detected cases for women aged 50-69 years relative to cases screened by use of MMG with CBE.
Conclusions: In terms of the survival and risk of breast cancer death, MMG with CBE may be more effective than MMG alone or self-detection for Japanese women aged 40-69 years.