Clinical guidelines are developed using research data, or evidence, to guide surgeons in the treatment of their patients. In 1995 clinical guidelines were developed on breast cancer treatment, recommending that radiotherapy treatment should follow breast conserving surgery (BCS). The Breast Section of the Royal Australasian College of Surgeons would like at least 85% of these patients to receive radiotherapy.

To see whether the guidelines led to a change in breast cancer treatment practice, researchers looked at data submitted by surgeons to the National Breast Cancer Audit (NBCA). In the decade after the guidelines were introduced, the number of BCS patients who did not receive radiotherapy dropped by half. By 2007 almost 90% of BCS patients received radiotherapy, more than expected by the Breast Section. Patients were less likely to receive radiotherapy after BCS if they were older (30% of patients over 70 years compared with 5-6 % of women under 70 years) or at low risk (with smaller, less aggressive tumours and with no information about the lymph gland status).

In conclusion, most breast surgeons are following the recommendation for radiotherapy following BCS. For some patients with good prognostic factors it may be reasonable to omit radiotherapy. Large data collections like the NBCA can be used to monitor whether clinical guidelines are changing practice.