Neoadjuvant therapy (NAT) in early breast cancer (EBC): Results from a prospective observational multicenter BRIDE study.

e12582 Background: To assess percentage of EBC pts treated with NAT in Italy, criteria of selection and types of therapies, we conducted an analysis in pts enrolled in BRIDE study. Methods: Primary objective of BRIDE was to evaluate distribution of stage I-II-III BC pts candidate to NAT and to determine both parameters that influenced the physician choice treatment (NAT or surgery) and type of NAT. Also treatment of stage IV was evaluated. Secondary objectives were DFS, PFS, OS estimate and implementation in clinical practice of AIOM v.2017 BC Guidelines. Were eligible pts with histological diagnosis of in situ or invasive carcinoma; stage I-IV (TNM v. VII); availability of cTcNM and/or pTpNM, biological parameters (G, ER/PgR, Ki-67, HER2 status); female, aged ≥18 years; written informed consent. The source of data was patients’ medical charts. The logistic regression model was used to statistically detect and estimate clinico-pathological imbalances between NAT and surgical pts. Results: From 01/2018 to 01/2021, 1633 pts with newly diagnosed BC were enrolled in BRIDE from 19 Italian cancer centres. Of 1250 stage I-II-III pts, 174 (14.0%; 95% CI 12.1-16.0%) were treated with NAT and 1073 with up front surgery (missing data: 3 pts). Pts and tumor characteristics of 174 NAT pts were compared to 1073 referred to surgery. The analysis showed in 174 NAT respect to 1074 surgical pts lower median age (50.6 vs 62.4 years; p <.0001) and higher percentage of premenopausal status (53.8% vs 28.9%; p <.0001), clinical stage II (64.4% vs 30.3%; p <.0001) and III (27.0% vs 6.3%; p <.0001); ductal carcinoma (74.1% vs 60.0%; p<.001); G3 (61.1% vs 24.8%; p <.0001); Ki-67 ≥20 (63.9% vs 39.7%; p <.0001); triple negative (TN) (16.9% vs 6.4%; p <.0001), HER2+/HR+ (26.2% vs 11.0%; p <.0001) and HER2+/HR- (20.9% vs 2.8%; p <.0001) subgroups. Tumor size and lymph node status at diagnosis also influenced oncologists' choice of administered NAT: 23.4% (95% CI 19.8-27.2%; p <.0001) of patients with T>2cm and/or LN+ received NAT. According to phenotypic subgroup, NAT was administered in 30.2% of TN, 28.1% of HER2+/HR+, 55.4% of HER2+/HR-, 6.9% of HER2-/HR+. The type of NAT were: chemotherapy in 100% of TN, 6.0% of HER2+/HR-, 90.3% of HER2-/HR+ patients; chemotherapy+anti-HER2 agent in 98.0% of HER2+/HR+ and 94% in HER2+/HR- patients; hormonal therapy (HT) in 9.6% of HER2-/HR+; HT+anti-HER2 agent in one older HER2+/HR+ BC pts. Conclusions: These results showed that in clinical practice pts (age, PS, menopausal status) and tumor (stage; G; Ki-67; T>2cm and/or N+ status; phenotypic subgroup) characteristics reported in Guidelines influenced oncologists in the choice of administrate NAT in EBC. It is necessary to increase the use of NAT in TN and HER2+ EBC, considering what alternative treatments are now available for residual disease after NAT.