Sharp increase in the incidence of mammary Carcinoma in Kagoshima prefecture, Japan

Between 1986 and 1990, among a female population of about 0.95 million, 1184 women living in Kagoshima Prefecture were diagnosed pathologically as having mammary carcinoma. The number of patients with mammary carcinoma, the crude incidence rate per 100 000 women and age-standardized mammary carcinoma incidence rates were 205, 21.29 and 19.42 in 1986, 212, 22.04 and 19.48 in 1987, 238, 24.74 and 21.8 in 1988, 245, 25.47 and 22.33 in 1989 and 284, 29.57 and 25.69 in 1990, respectively. The number of patients with this disease increased annually. The increase in the age-specific incidence rate of this type of cancer between 1986 and 1990 was 1.38-fold in women between 40 and 49 years of age, 1.46-fold in women between 50 and 59, 1.37-fold in the 60–69 age group, 1.48-fold in the 70–79 age group and 1.91-fold in women over 80. In both the urban and rural areas, the incidence increased annually during the course of this study. In 1990, the age-standardized mammary carcinoma incidence rate in urban area was 1.17 times that in rural area.