Axillary dissection and ductal carcinoma in situ of the breast: a change in practice.

Background: Axillary dissection may be associated with significant morbidity and, while it is necessary in the treatment of invasive breast cancer, is not indicated for the treatment of pure ductal carcinoma in situ (DCIS), although it is being performed in a significant number of cases. The present study examined the incidence of elective axillary dissection in the treatment of DCIS cases detected in a mammographic screening programme over a 4-year period, and whether surgeons have changed their practice in this respect.

Methods: BreastScreen Victoria records were examined retrospectively for the period from January 1995 to December 1998 to identify patients treated for DCIS. The incidence and indications for axillary surgery were investigated.

Results: There were 579 cases of DCIS and 93 (16%) had some form of axillary surgery, which was thought to be inappropriate in 57 (10%), the latter being performed by 21 city surgeons and 20 rural surgeons. Before surgery, 36 (63%) cases were diagnosed by core biopsy or excision, and 21 (37%) had imaging and cytology alone for diagnosis. The rate of unnecessary axillary dissections dropped steadily from 14% in 1995 to 4% in 1998, a significant reduction (P = 0.01).

Conclusion: The incidence of axillary dissection for DCIS has dropped significantly over the last 4 years in Victoria, possibly due to increased awareness through education and guidelines. Surgeons are now more aware that in situ lesions do not need axillary dissection, and that axillary dissection should not be performed for breast cancer unless invasion has been proved histologically.