Background: Ductal carcinoma in situ (DCIS) often accompanies invasive breast cancer. The prognostic implication of this is unclear. We sought to determine whether concomitant DCIS affects outcomes in patients with invasive disease. Methods: A nested cohort study was performed of 1,709 invasive breast cancer patients. Clinicopathologic data, along with survival and recurrence data, were collected prospectively. Results: Concomitant DCIS was noted in 434 (25.4%) patients. Median follow-up was 59 months. On univariate analysis, the presence of DCIS was associated with a trend toward improved 5-year disease-free survival (93.6% vs 90.5%; P = .089) and overall survival (95.3% vs 92.6%; P = .058). Further, DCIS was associated with younger patient age (median 65 vs 68 years; P < .0001), smaller tumor size (median 1.37 vs 1.44 cm; P = .069), fewer palpable tumors (27.4% vs 33.3%; P = .051), more high-grade tumors (19.1% vs 15.8%; P = .045), and invasive ductal histology (90.6% vs 79.0%; P < .0001). On multivariate analysis, DCIS was not, however, an independent predictor of improved disease-free (odds ratio [OR], 0.715; P = .217) or overall survival (OR, 0.770; P = .251). Conclusion: Although the presence of DCIS is often associated with favorable features, it is not an independent predictor of improved outcome in patients with concomitant invasive breast cancer.
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