Outcomes from low-risk ductal carcinoma in situ: a systematic review and meta-analysis

Abstract

Abstract Purpose The current standard of treatment for ductal carcinoma in situ (DCIS) is surgery with or without adjuvant radiotherapy. With a growing debate about overdiagnosis and overtreatment of low-risk DCIS, active surveillance is being explored in several ongoing trials. We conducted a systematic review and meta-analysis to evaluate the recurrence of low-risk DCIS under various treatment approaches. Methods PubMed, Embase, Web of Science, and Cochrane were searched for studies reporting ipsilateral breast tumour event (IBTE), contralateral breast cancer (CBC), and breast cancer-specific survival (BCSS) rates at 5 and 10 years in low-risk DCIS. The primary outcome was invasive IBTE (iIBTE) defined as invasive progression in the ipsilateral breast. Results Thirty three eligible studies were identified, involving 47,696 women with low-risk DCIS. The pooled 5-year and 10-year iIBTE rates were 3.3% (95% confidence interval [CI]: 1.3, 8.1) and 5.9% (95% CI: 3.8, 9.0), respectively. The iIBTE rates were significantly lower in patients who underwent surgery compared to those who did not, at 5 years (3.5% vs. 9.0%, P = 0.003) and 10 years (6.4% vs. 22.7%, P = 0.008). Similarly, the 10-year BCSS rate was higher in the surgery group (96.0% vs. 99.6%, P = 0.010). In patients treated with breast-conserving surgery, additional radiotherapy significantly reduced IBTE risk, but not total-CBC risk. Conclusion This review showed a lower risk of progression and better survival in women who received surgery and additional RT for low-risk DCIS. However, our findings were primarily based on observational studies, and should be confirmed with the results from the ongoing trials.