Are We Overtreating Ductal Carcinoma in Situ (DCIS)?

During 2015, the media was flooded with the issue of whether ductal carcinoma in situ (DCIS) was being overtreated and whether favorable cases could be simply watched (core biopsy only followed by surveillance). To answer this question, we looked at DCIS patients treated with excision alone with margin width < 1 mm as inadequate and a surrogate for no treatment (surveillance group) and margin >= 1 mm as adequate surgical excision (excision group). A total of 720 patients with pure DCIS treated with excision alone were stratified into two groups based on margin width and further subdivided by nuclear grade. Kaplan-Meier analysis was used to determine local recurrence-free survival. Differences in outcome were analyzed using the log-rank test. The 10-year local recurrence probabilities are statistically significant for low-grade versus high-grade and surveillance alone versus excision alone. The comparison of excision alone group with margins >= 1 mm for low-grade DCIS versus high-grade DCIS shows a 10-year local recurrence-free survival rate of 13 versus 35 % (p < 0.0001). The surveillance group had (margins < 1 mm) had higher rates of recurrence in both the low-grade group (51 %) and high-grade group (70 %) (p < 0.001). This study indicates that there is not an acceptable level of local control in DCIS patients with tumor margins < 1 mm that undergo active surveillance, regardless of tumor grade. Leaving even low-grade DCIS untreated would lead to local recurrence in more than half the patients in 10 years. Needle biopsy and surveillance for DCIS, regardless of grade, is just not adequate at this time.