A large intergroup study has revealed that adjuvant radiation therapy (RT) for good-risk ductal carcinoma in situ (DCIS) led to over 50% reduction in long-term ipsilateral breast recurrence (IBR), in comparison with observation.

RT done after surgery with or without tamoxifen could reduce 15-year IBR from 15.1% with observation to 7.1%. It also led to a reduction in the odds of invasive local recurrence by over 50%. According to a multivariable analysis, RT had the greatest impact on IBR, which exceeded the risk-reducing effect of tamoxifen.

The primary analysis after a median follow-up of 7 years revealed that there was a significant reduction in IBR, favoring adjuvant RT. A report after a median follow-up of 12 years was still in favor of adjuvant RT, with an IBR rate of 2.6% compared to 11.4% with observation. The estimated cumulative 15-year IBR and invasive recurrence rates were reported after a median follow-up of 13.9 years. RT was shown to reduce the hazard for IBR by 64% and the hazard for invasive local recurrence by 56%. The findings are published in the Journal of Clinical Oncology… (Medpage Today)