Residual ductal carcinoma in situ in patients with complete eradication of invasive breast cancer after neoadjuvant chemotherapy does not adversely affect patient outcome.

PURPOSE: To determine whether residual ductal carcinoma in situ (DCIS) after completion of preoperative chemotherapy affects the outcome of patients with histologically defined complete eradication of invasive cancer. PATIENTS AND METHODS: Retrospective analysis of a database including 2,302 breast cancer patients treated with neoadjuvant chemotherapy at The University of Texas M.D. Anderson Cancer Center between 1980 and 2004 was performed. The overall survival (OS), disease-free survival (DFS), and local recurrence-free survival were compared for patients with no residual invasive or in situ cancer (pathologic complete response [pCR]) and patients with no residual invasive cancer but persistent in situ disease (pCR+DCIS).
RESULTS: The mean follow-up time was 250 months. Of the 2,302 treated patients, 78 (3.4%) had pCR, 199 (8.6%) had pCR+DCIS, and 2,025 (88%) had residual invasive cancer. For patients with pCR and pCR+DCIS, the 5-year DFS rates (87.1% in both groups) and 10-year DFS rates (81.3% v 81.7%, respectively) were similar; the 5-year OS rates (91.9% v 92.5%, respectively) and 10-year OS rates (91.8% v 92.5%, respectively) were also similar and significantly better than the rate of patients with residual invasive cancer (74.4%; P < .001). The 5-year locoregional recurrence-free survival rates were also not different between patients with pCR (92.8%; 95% CI, 86.1% to 96.4%) and patients with pCR+DCIS (90.9%; 95% CI, 77.3% to 96.5%; P = .63).
CONCLUSION: Residual DCIS in patients who experience complete eradication of the invasive cancer in the breast and lymph nodes does not adversely affect survival or local recurrence rate. Inclusion of patients with residual DCIS in the definition of pCR is justified when this outcome is used as an early surrogate for long-term survival.