National breast cancer audit: overview of invasive breast cancer management.

Background: The National Breast Cancer Audit is an initiative of the Breast Section of the Royal Australasian College of Surgeons collecting surgical information in early breast cancer. It is managed in conjunction with the Australian Safety and Efficacy Register of New Interventional Procedures - Surgical. An overview of results for invasive breast cancer from January 1999 until December 2004 is presented to provide preliminary data for participating surgeons.

Methods: Invasive breast cancer cases were retrieved from the National Breast Cancer Audit database for the 274 participating breast surgeons in Australia and New Zealand. Data for a variety of clinical parameters were analysed to provide an overview of the diagnostic, histological, surgical and adjuvant therapy management issues.

Results: There were 25,026 cases of invasive breast cancer. Annual percentages of mammographically detected cancers from 1999 to 2004 did not differ significantly. Breast-conserving surgery rates also remained stable at 60%. Margins were involved in 5% of patients; an additional 9% had final margins of less than 1 mm. Radiotherapy followed breast-conserving surgery in most cases (86%). Patients undergoing mastectomy with large tumours (>5 cm) underwent radiotherapy in 71% of cases. When at least four lymph nodes were positive, radiotherapy followed mastectomy in the majority (75%) of cases. The most frequently carried out axillary procedure was a level 2 dissection. Chemotherapy was received by 78% of oestrogen receptor negative, axillary node positive, postmenopausal patients. Tamoxifen was used in the majority (83%) of oestrogen receptor positive cases.

Conclusion: Surgeons contributing their invasive breast cancer data show a high quality of treatment. Some further improvement may be possibly related to excision margins and tamoxifen prescription for oestrogen receptor negative cancers. Chemotherapy prescription might also warrant further investigation.