No breast cancer subgroup can be spared postoperative radiotherapy after breast-conserving surgery. Fifteen-year results from the Swedish Breast Cancer Group randomised trial, SweBCG 91 RT

RT after BCS significantly reduced the incidence of IBTR at 15 years of follow-up. We were unable to identify subgroups which could be spared RT. Breast cancer mortality was not significantly reduced after RT. Good predictive markers for radiation sensitivity and improved adjuvant systemic therapy are needed to omit RT after BCS.