Breast conservation, mastectomy and axillary surgery in New South Wales women in 1992 and 1995.

To measure the increase in uptake of BCT in NSW and its determinants, we examined Cancer Registry records of 2020 women with breast cancer in 1992 and 2883 in 1995 linked to records of their surgical treatment in the NSW Inpatient Statistics' Collection. In parallel, we examined trends and determinants in axillary surgery for breast cancer. Breast conservation increased from 39% of breast cancer in 1992 to 45% in 1995, mainly in women with the smallest cancers. In 1995, mastectomy was still most common in women with larger cancers (OR for breast cancers 3+ cm relative to <1 cm = 5.6, 95% CI 2.9-10.7) and cancers that had spread beyond the breast (OR = 2.0, 95% CI 1.4-2.7 relative to localized to the breast). Urban women had fewer mastectomies than rural women. Axillary surgery, common in 1992 (78%) and 1995 (82%), fell steeply with increasing age and more often accompanied mastectomy (93% in 1995) than BCT (67% in 1995). In 1995 the odds for axillary surgery were some two-fold or more higher for all cancers 1 cm or more in diameter compared with those <1.0 cm and highest for 2.0-2.9 cm cancers (OR = 3.3 95% CI 1.7-6.7 relative to <1.0 cm). Regional spread of the cancer at diagnosis was not a strong predictor. In the absence of collection of treatment data by cancer registries, linkage of cancer registry records with hospital inpatient data is an effective alternative for monitoring breast cancer treatment trends.