The profile of breast cancer in Western Australia.

Information concerning all 435 women who presented with primary breast cancer in Western Australia during 1984 was obtained by a review of the WA Cancer Registry, hospital, histopathological laboratory, and medical practitioner records. The age-standardized and cumulative incidence rates were 55.7 per 100,000 women and 6.4%, respectively. The probability that a woman would develop breast cancer during her lifetime (to the age of 74 years) was one in 15.6. There was a significant seasonal variation in the incidence of breast cancer, with a peak in spring (November) and a low in winter (July). The highest incidence rates occurred in women who had never had any children, those of professional status and those who lived in better socioeconomic areas. Stage-I disease accounted for only 22% of all breast cancers. A younger age was associated with a greater proportion of oestrogen-receptor-negative tumours and a longer symptom interval correlated with larger primary tumours. The findings support the concept that the characteristics of Australian women with breast cancer are similar to those that have been described in British and North American women.