Correlation of size and focality with prognosis in small breast carcinoma: a single institution case series

Aim of the study: The clinical behavior and prognosis of small multifocal and microinvasive breast cancers are still debated together with the best method of assessing tumor size in multiple invasive carcinomas. This study evaluates the clinico-pathological features of single and multiple breast cancers up to 0.5 cm in order to evaluate the rate of recurrences. Materials and methods: We retrospectively analyzed 170 node-negative patients consecutively treated at European Institute of Oncology from 2001 to 2006. We divided them into Group I (pT1mi) and Group II (pT1a) furtherly divided in subgroups, according to focality and aggregate diameter. For each group we assessed tumor size, (multi)focality, extensive in situ component (EIC), histology, grade, peritumoral vascular invasion (PVI), hormonal receptor status (HR), HER-2 expression, Ki67 expression. Results: We observed that the frequency of local recurrences and distant metastases in group I was higher among those with a single focus; whereas in group II, it was higher in multifocal carcinomas. Then, by comparing the two groups, the prognosis was better in multiple pT1mi than in similarly sized unifocal pT1a. Conclusions: Microinvasive carcinomas are associated with a good prognosis, even if they seem to have a more aggressive intrinsic biological behavior. Multifocality seems to be correlated with a worse prognosis in case of invasive carcinomas pT1a. In case of microinvasive carcinomas, by contrast, multifocality per se does not seem to affect the recurrence rate.