Clinical Implications of Growth Pattern and Extension of Tumor-Associated Intraductal Carcinoma of the Breast

IntroductionThe goal of the present study was to identify the clinically relevant features of tumor-associated intraductal component (IDC) surrounding invasive breast cancer.Patients and MethodsThe tumor specimens from 410 patients with primary invasive breast cancer were investigated. The distance between the surgical margins and tumor edge (invasive and intraductal areas) was measured prospectively.ResultsOf the 410 investigated patients, 395 were eligible for analysis. An IDC was observed in 241 specimens (61.0%) and was associated with a younger age at diagnosis, postmenopausal status, and positive estrogen receptor, progesterone receptor, and human epidermal growth factor 2 (HER2) expression status. Most cases with tumor-associated ductal carcinoma in situ (DCIS) were found in the upper-outer quadrants of the breasts. An extended intraductal component (EIC) tended to be present in the outer and lower quadrants of the breasts. In the study cohort of 187 patients with tumor-associated DCIS, 1496 surgical margins were investigated. IDC was associated with invasive tumor growth predominantly in the nipple direction. The nipple-associated growth of DCIS correlated with patient age > 40 years, tumor size ≤ 2 cm, poor histologic differentiation of the noninvasive and invasive components, and positive estrogen and progesterone receptor status and negative HER2 status.ConclusionsOur data provide evidence that in patients with primary breast cancer, the EIC areas will be mostly segmentally localized between the invasive tumor and the nipple. Therefore, if EIC is present or assumed, surgery should consist of segmental resection of the breast tissue, at least in patients with breast cancer who are > 40 years old, with a tumor size of < 2 cm, and with hormone receptor-positive and HER2-negative, poorly differentiated tumors.