Histopathological growth distribution of ductal carcinoma in situ: tumor size is not "one size fits all".

Background: Ductal carcinoma in situ (DCIS) is a group of preinvasive breast neoplasms. Studies have shown excellent survival among patients with lumpectomy-amenable disease. Patients requiring mastectomy have been less well characterized. We aim to characterize this cohort and identify whether growth distribution pattern is associated with sentinel lymph node involvement at time of surgery or subsequent development of metastatic disease. Methods: Patients were identified using local cancer registry data and were chart reviewed using electronic medical records. Growth pattern was classified as unifocal, multifocal, or diffuse. Chi-squared, Analysis of Variance (ANOVA), and Kaplan-Meier analyses were performed. Results: Two hundred and twenty-six patients were identified with median age at diagnosis 49 and follow up 7.1 years. 42 had unifocal, 51 had multifocal and 20 had diffuse lesions. 3/20 patients with diffuse type lesions developed subsequent distant metastatic disease, while none of the patients with unifocal or multifocal lesions did. 1/20 patients with diffuse and 2/51 with multifocal disease had sentinel lymph node involvement (SLNI) at surgery. Tumor extent was not associated with sentinel lymph node involvement or distant metastatic disease (P=0.2, Kaplan-Meier analysis) but growth pattern was (P=0.01). It was also associated on Kaplan-Meier with development of distant metastatic disease alone (P=0.01). Conclusions: Patients with diffuse growth pattern DCIS were more likely to have SLNI or development of distant metastatic disease. Our findings suggest that patients with diffuse type lesions are at greater risk of metastatic disease and therefore breast cancer death from DCIS. Optimal therapy for these patients will need further elucidation.