Locally advanced breast cancers: the EUSOMA experience.

[BACKGROUND] The aim of this study was to assess clinicopathologic characteristics, treatment modalities used and outcome of patients with locally advanced breast cancer (LABC).

[MATERIALS AND METHODS] we searched the European Society of Breast Cancer Specialists (EUSOMA) data warehouse for clinically LABC cT4a-d - in the 2013-2022 timeframe.

[RESULTS] Of a total of 132269 patients, we identified 2427 patients with cT4abc BC (1.83 %) and 977 with inflammatory (T4d) BCs (0.74 %), of whom 542/2427 (20.1 %) and 251/977 (25.6 %), respectively, had metastatic disease at presentation (p = 0.054. Ninety percent of patients with cT4abcM0 and 88.8 % of patients with cT4dM0 disease had surgery (p = 0.369) and 90.9 % and 88.7 % (p = 0.187) endocrine therapy. Neoadjuvant chemotherapy (CT), adjuvant CT, biological drugs and radiotherapy were given in 33.2 %, 47.0 %, 67.1 % and 61.1 % of cT4abcM0 cases compared to 77.3 %, 80.4 %, 87.7 % and 80.2 % of cT4dM0 cases (all p < 0.001). Multivariable analysis showed that age <70 years, luminal A and HER-2 pure subtype, surgical treatment, radiotherapy, and systemic treatment (all p ≤ 0.034) were determinants of better overall survival (OS). Local recurrence rate (LRR) was significantly lower in patients receiving radiotherapy or endocrine therapy (p ≤ 0.012). Cox analyses showed no difference in OS or LRR between patients with cT4abc and those with T4d BCs, neither at univariable or multivariable analysis.

[CONCLUSIONS] The current study confirms well-known features of cLABCs and underscores the importance of multimodal treatment, which is often underused in these patients.