Aim: To summarise the results of randomised trials testing the addition of radiotherapy (RT) to breast conserving surgery for ductal carcinoma in situ (DCIS); to determine whether there are subsets of women with DCIS who do not benefit from RT; and to determine what the balance may be between reduction in risk of recurrence and long-term toxicity.
Methods: We performed a systematic review to resolve these questions, using standard Cochrane methodology to identify, select and appraise relevant randomised trials.
Results: Four randomised controlled trials involving 3925 women were identified. All were high quality with minimal risk of bias. Analysis confirmed a statistically significant benefit from the addition of radiotherapy on all ipsilateral breast events (HR=0.49; 95% CI 0.41-0.58, p<0.00001). All subgroups analysed (margin status, age and grade) benefited from the addition of radiotherapy. Nine women require treatment with radiotherapy to prevent one ipsilateral breast recurrence (NNT=9). Deaths due to vascular disease, pulmonary toxicity and second cancers were low and not significantly higher for women who received radiotherapy.
Concluding statement: Radiotherapy was beneficial in all clinically relevant subgroups. Longer follow-up is required to detect any long-term toxicity from use of radiotherapy. To date, no increase in toxicity has been identified.