CANCER OF THE BREAST IN ONTARIO.

The breast is the leading cancer site among women; it accounts for 20% of all female cancer deaths. The lifetime probability of death from breast cancer for a female born in Ontario is 3.3%; that is, one in every 30 women will die of breast cancer. The risk of developing breast cancer is almost twice this figure.The medical certificate of death yields a reliable estimate of the number of persons who die of breast cancer, and the level of the age-specific breast cancer death rates has not changed over the past 30 years. Cohort analysis yields an indistinguishable mortality pattern for succeeding cohorts of women from 1871. Available information indicates no change in incidence.The stable mortality and incidence rates suggest that there has been little or no change in the survival rate, despite emphasis on early diagnosis and improvement in therapeutic skills and in technical facilities.