AUTHOR=Metovic Jasna , Bragoni Alberto , Osella-Abate Simona , Borella Fulvio , Benedetto Chiara , Gualano Maria Rosaria , Olivero Elena , Scaioli Giacomo , Siliquini Roberta , Ferrando Pietro Maria , Bertero Luca , Sapino Anna , Cassoni Paola , Castellano Isabella 

TITLE=Clinical Relevance of Tubular Breast Carcinoma: Large Retrospective Study and Meta-Analysis

JOURNAL=Frontiers in Oncology

VOLUME=Volume 11 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.653388

DOI=10.3389/fonc.2021.653388

ISSN=2234-943X

ABSTRACT=Background: Tubular Carcinoma (TC) is a low proliferative grade 1 (G1) breast cancer (BC). Despite its favorable outcome and allegedly lower aggressiveness, patients are treated like other luminal G1 BC, with radiotherapy (RT) and hormonal therapy (HT). We performed: (1) a retrospective study comparing a TC cohort and a control series of luminal G1 BC; (2) a systematic review and meta-analysis focused on TC outcome. 
Materials and methods: We selected a series of 572 G1 luminal BC (111 TC, 350 not otherwise specified (NOS) and 111 special type (ST) BCs) with follow-up and clinico-pathological data, who underwent local excision followed by RT at Città della Salute e della Scienza Hospital, Turin. Moreover, 22 and 13 studies were included in meta-analysis, respectively. 
Results: TCs were generally smaller (<10 mm) (P<0.01), with lower lymph node involvement (P<0.001). TCs showed no local and/or distant recurrences, while 16 NOS and 2 ST relapsed (P=0.036) (median follow-up 9.3 years). Kaplan-Meier curves confirmed more favorable TC outcome (DFI: Log-Rank Test P=0.03). Meta-analysis data, including the results of our study, showed that the pooled DFI rate was 96.4% and 91.8% at 5 and 10 years, respectively. Meta-regression analyses did not show a significant influence of RT nor HT on the DFI at 10 years.
Conclusions: Compared to the others G1 BCs, TCs have an excellent outcome. The meta-analysis shows that TC recurrences are infrequent, and HT and RT have limited influence on prognosis. Hence, accurate diagnosis of TC subtype is critical to ensure tailored treatment approach.