Tubular Carcinoma of the Breast: Clinicopathologic Features and Survival Outcome Compared with Ductal Carcinoma In Situ

PURPOSE: Tubular carcinoma (TC) of the breast is an uncommon histological subtype of invasive breast cancer with an excellent prognosis compared with standard invasive ductal carcinoma. Recent studies suggested a possible precursor role for low grade ductal carcinoma in situ (DCIS) in the development of TC. The goal of this analysis was to understand the clinicopathologic features and outcomes of TC by comparing TC with DCIS. METHODS: A retrospective review identified 70 patients with TC and 1,106 patients with DCIS between 1995 and 2011. Student t-test and Fisher exact test were used to compare the clinicopathologic characteristics of TC patients with those of DCIS patients. The Kaplan-Meier method and Cox regression analysis were used to determine disease-free survival (DFS) rates. RESULTS: Compared to DCIS, TC exhibited favorable clinicopathologic characteristics such as a lower nuclear grade (92.3%), higher expression of hormonal receptors (estrogen receptor-positive, 92.9%; progesterone receptor-positive, 87.0%), and less frequent overexpression of human epidermal growth receptor 2 (12.9%). DFS did not differ significantly between the TC and DCIS groups (5-year DFS, 100% vs. 96.7%; 10-year DFS, 92.3% vs. 93.3%; p=0.324), and cancer-specific deaths were not noted in either group. However, axillary lymph node involvement was observed in six (8.6%) of the 70 patients with TC. Three of these patients had small tumors (≤1 cm). CONCLUSION: In our study cohort, TC was associated with an excellent prognosis and a low rate of lymph node metastasis. However, lymph nodes metastases were found even in patients with small tumors (≤1 cm). Axillary staging must be considered for all patients with TC of the breast.