Impact of Radiation Therapy on Breast Conservation in DCIS

Patients and their physicians are often confronted with a decision between more intensive versus less intensive treatment for a particular diagnosis. Quality decision-making between these options requires careful balancing of the risks and side-effects, as well as weighing the expected outcomes and their associated value as assessed by the patient. Although the incidence of DCIS has risen dramatically (1), there exists considerable debate about optimal treatment. In general, people with DCIS have high rates of recurrence-free survival. Intensive therapies for DCIS such as mastectomy (removal of the breast) or radiation therapy following BCS reduce the likelihood of a second breast diagnosis,(2-5) but have not been shown to improve survival.(6) In addition, radiation usually necessitates mastectomy should a new cancer or DCIS develop in the same breast at any point during the patient's lifetime. Patients also have a small chance of experiencing long-term toxicity. Previous radiation can also complicate reconstructive options following mastectomy. The tradeoff between risk of second breast diagnosis and side-effects and potential consequences of radiation therapy underscores the need for patient preference-driven decision making. Patients who receive BCS alone without radiation therapy may be candidates for repeat BCS if they have a second breast event in the same breast. One study suggests that some women choose not to have radiation after DCIS because they want to preserve a breast-preservation option should a second breast diagnosis occur.(7) However, the likelihood of mastectomy versus BCS at time of new diagnosis in a previously un-irradiated breast is variable.(8-10) Whether a woman receives repeat breast-conserving surgery for a new diagnosis may not only be a function of the stage of diagnosis, but may be also determined by the regional treatment patterns used for management of DCIS. We sought to study whether regional intensity of radiation use for DCIS treatment increases the likelihood of mastectomy at time of second breast event, among women who have not received radiation therapy at initial DCIS diagnosis. (Punglia RS, Cronin AM, Uno H, et al. Association of Regional Intensity of Ductal Carcinoma In Situ Treatment With Likelihood of Breast Preservation. JAMA Oncol. Published online July 21, 2016.)