Radiotherapy after conservative surgery for breast cancer: selective use of iridium-192 wire boost to tumour bed in high risk patients.

The results of treatment for 51 patients referred for radiotherapy after local excision of an 'early' breast carcinoma are reviewed. The patients were considered to be at particularly high risk of local recurrence due to the presence of one or more adverse histological features, most commonly microscopic involvement of resection margins. The patients received a course of whole-breast irradiation (40 Gy in 15 fractions over 3 weeks) but instead of following this with a routine photon or electron tumour-bed boost (15 Gy in five fractions) these patients received an iridium-192 wire implant, giving a tumour-bed boost of 25 Gy over approximately 3 days. After a median follow-up of 38 months, five patients have recurred locally within the breast, giving an actuarial breast recurrence-free survival of 87.8% at 8 years. Four patients have died of metastatic breast cancer, none of whom had uncontrolled local disease. Cosmesis was good or excellent in 76% of cases. The presence of microscopic tumour at resection margins or other adverse histological features is not, therefore, necessarily an indication for further surgery, as a good level of local control can still be achieved with radiotherapy providing a relatively high-dose tumour-bed boost is employed using an iridium-192 wire implant.