Characteristics of Microinvasive Ductal Carcinoma In Situ Versus Noninvasive and Invasive Breast Cancer

The present literature is conflicting regarding the management of microinvasive ductal carcinoma in situ (miDCIS) as to following recommendations for DCIS (margin status, surgical axillary staging, and possible observation) versus invasive breast cancer. We hypothesize that miDCIS represents more aggressive disease than pure DCIS.We performed a retrospective review of female miDCIS patients compared with age-matched cohorts of DCIS and T1b/c patients with invasive breast cancer. We collected demographic, clinicopathologic, treatment, and outcome information. Analysis of variance or Kruskal-Wallis tests were used to analyze continuous variables and chi-square or Fisher's exact tests for categorical variables. Survival outcomes were analyzed using Kaplan-Meier curves.We included 375 patients (125 in each group) with median age 59 y (range 33-91 y). miDCIS tumors were more likely to be hormone receptor negative and human epidermal growth factor receptor 2 positive compared with DCIS or invasive ductal carcinoma (IDC; all P 0.001). Subgroup analysis by miDCIS focality demonstrated no significant differences. The number of involved lymph nodes was not significantly different from DCIS patients but was significantly fewer than invasive cancer patients. Of 115 miDCIS patients (88%) staged with sentinel lymph node biopsy, eight (7%) had nodal metastases. Six miDCIS patients (5%) were treated with adjuvant chemotherapy. Over a median follow-up of 23.3 mo, there were no significant differences in local or distant recurrence.Based on our results, miDCIS has more aggressive pathologic features compared with DCIS and warrants surgical treatment and nodal staging similar to the management of IDC. In addition, similar to IDC, nodal and receptor status may influence medical management.