Audit of local recurrence following breast conservation surgery with 5-mm target margin and hypofractionated 40-Gray breast radiotherapy for invasive breast cancer

The risk of ipsilateral breast tumour recurrence (IBTR) following breast conservation surgery (BCS) for invasive breast cancer (IBC) and radiotherapy is dependent on patient-, tumour- and treatment-related variables. In the Cambridge Breast Unit, breast conserving surgery has been performed with a target radial margin of 5 mm for IBC, in combination with 40-Gy hypofractionated (15 fractions) breast radiotherapy, since 1999. An audit was performed of cases treated between 1999 and 2004. A total of 563 patients underwent BCS for invasive breast cancer with 90.4% receiving radiotherapy (RT) and 60.4% of patients receiving boost RT (3 fractions of 3-Gy). After a median follow-up of 58 months, five of the 563 (0.9%) patients developed IBTR. The 5-year actuarial IBTR rate was 1.1%. In terms of distant disease recurrence (DDR), 29 of the 563 (5.2%) had DDR during follow-up, giving a 5-year actuarial DDR rate of 5.4%. The 5-year breast cancer specific survival was 95%, with the poorer NPI groups having worse breast cancer specific survival (Log-rank, P