Ductal carcinoma in situ with microinvasion: prognostic implications, long-term outcomes, and role of axillary evaluation.

Abstract

To compare the clinical-pathologic features and long-term outcomes for women with ductal carcinoma in situ (DCIS) vs. DCIS with microinvasion (DCISM) treated with breast conservation therapy (BCT), to assess the impact of microinvasion. A total of 393 patients with DCIS/DCISM from our database were analyzed to assess differences in clinical-pathologic features and outcomes for the two cohorts. The median follow-up was 8.94 years, and the mean age was 55.8 years for the entire group. The DCISM cohort was comprised of 72 of 393 patients (18.3%). Surgical evaluation of the axilla was performed in 58.3% (n = 42) of DCISM vs. 18.1% (n = 58) of DCIS, with only 1 of 42 DCISM (2.3%) vs. 0 of 58 DCIS with axillary metastasis. Surgical axillary evaluation was not an independent predictor of local-regional relapse (LRR), distant relapse-free survival (DRFS), or overall survival (OS) in Cox proportional hazards analysis (p > 0.05). For the DCIS vs. DCISM groups, respectively, the 10-year breast relapse-free survival was 89.0% vs. 90.7% (p = 0.36), DRFS was 98.5% vs. 97.9% (p = 0.78), and OS was 93.2% vs. 95.7% (p = 0.95). The presence of microinvasion did not correlate with LRR, age, presentation, race, family history, margin status, and use of adjuvant hormonal therapy (all p > 0.05). In univariate analysis, pathology (DCIS vs. DCISM) was not an independent predictor of LRR (hazard ratio [HR], 1.58; 95% confidence interval [CI], 0.58-4.30; p = 0.36), DRFS (HR, 0.72; 95% CI, 0.07-6.95; p = 0.77), or OS (HR, 1.03; 95% CI, 0.28-3.82; p = 0.95). Our data imply that the natural history of DCISM closely resembles that of DCIS, with a low incidence of local-regional and distant failures. On the basis of our large dataset, the incidence of axillary metastasis in DCISM appears to be small and not appear to correlate to outcomes, and thus, microinvasion alone should not be the sole criterion for more aggressive treatment.