The DCIS Cochrane review by Goodwinr, including 4 RCTs (NSABP B-17, EORTC10853, UKCCCR and SweDCIS) (n=3925 women) comparing the addition of radiotherapy to breast conserving surgery (BCS), reported statistically significant benefit from the addition of radiotherapy on all ipsilateral breast events (HR 0.49; 95% CI 0.41-0.59, P< 0.00001) and ipsilateral DCIS recurrence (HR 0.64; 95% CI 0.41 to 1.01, p=0.05). The addition of radiotherapy reduced the risk of a recurrence of either DCIS or invasive cancer in the treated breast by 51%.
The 15-year combined analysis of the NSABP B-17 and B-24 trialsr show that the reduction in risk of local recurrence appears to persist in the long term. The ipsilateral breast recurrence rate is reduced from 19.4% to 8.9% with radiotherapy at 15 years. The overall survival rate was similar, 83% versus 84%.
Further evidence supporting this protocol is provided by a second meta-analysis, reviewing individual patient data for the same four randomized trialsr (NSABP B-17, EORTC10853, UKCCCR and SweDCIS), examining 3729 women over a 10-year period, comparing breast conserving surgery alone to breast conserving surgery with adjuvant radiotherapy. 10-year ipsilateral breast recurrence with surgery alone was 28% compared to 13% for breast conserving surgery with radiotherapy (statistically significant). This benefit was greater in women >50 (28% vs 11%) compared with women <50 (29% vs 18%). Women with small, low-grade tumors and negative surgical margins still benefited (30% vs 12%, statistically significant). There was no effect on breast cancer specific mortality (~4%), other-cause mortality (~5%), and all-cause mortality (~8%).
Summary of results from Bijker et al:r 10-year local recurrence (LR): DCIS 14% BSC vs. 7% BSC + RT (statistically significant), 48% reduction. Increased risk for LR: age <40, grade 2 or 3, cribiform or solid growth pattern, doubtful margin, and local excision alone. Size was not a prognostic factor. No difference in overall survival or distant mets.
20 year follow-up of the sweDCIS trialr shows that the absolute risk reduction of ipsilateral breast recurrence in the RT arm was 12.0% at 20 years (95% CI, 6.5 to 17.7), with a relative risk reduction of 37.5%. Absolute reduction was 10.0% (95% CI, 6.0 to 14.0) for DCIS.
There is high level evidence that radiotherapy offers an advantage of local control in all groups. However, the benefit should be considered in the context of small absolute gains for certain small subgroups.r
The patient should be discussed at an MDT and management options discussed with the patient. LORIS, a Phase III trial investigating Surgery vs Active Monitoring for Low risk DCIS patients is currently underway.r Consider the use of a DCIS Recurrence nomogramr to assist in decision making.
The role of the use of hypofractionated radiotherapy and breast boost are examined in a meta-analysis of observational trials published in 2015.r No difference in the risk of local recurrence was observed between the patients that received boost vs. no boost in the general cohort (12 studies, 6943 patients; Odds Ratio [OR]: 0.91, 95% CI: 0.77-1.08, very low level of evidence). There was a reduced risk for local recurrence when a boost was administered in patients with positive margins compared to no boost (6 studies, 811 patients; OR: 0.56, 95% CI: 0.36-0.87, very low level of evidence). No difference in local recurrence rate between patients who received hypofractionated versus standard radiotherapy was observed (4 studies, 2534 patients; OR: 0.78, 95% CI: 0.58-1.03, low level of evidence). These studies provide a low level of evidence.
We await the results of the randomised TROG DCIS trialr regarding hypofractionation and boost for DCIS patients where accrual has been completed.