132P Clinico-pathological characteristics, treatments and survival outcomes of patients with high-risk hormone receptor positive early breast cancer (HR+ BC) in French real-world (RW) setting: A study from CANTO cohort

Patients with HR+ BC with unfavourable features have an increases risk of relapse. Our aim was to describe clinico-pathological characteristics, adjuvant treatments and survival outcomes of patients with high-risk HR+ BC, using RW data reported in the Cancer Toxicities (CANTO) prospective observational study (NCT01993498). Baseline features and treatment patterns were collected from CANTO cohort for all women with HR+ BC at high-risk of relapse defined either (1) ≥ 4 positive pathologic axillary lymph nodes (LN) or (2) 1 to 3 positive axillary LN with a tumor size ≥ 5 cm or grade III. HR+ BC not respecting these criteria were classified as non-high risk. Invasive disease free survival (IDFS) and distant metastasis free survival (DMFS) were calculated. Bilateral BC were excluded. Among HR+ BC patients, 1266 (15.0%) were at high-risk of relapse. The median age at diagnosis was 54.3 yrs (range 22-87), 589 (47.2%) were premenopausal, and 79.9% had a favorable Charlson comorbidity score. Germline BRCA1 or BRCA2 mutations were reported in 3.5% and 8.0%, respectively. 617 patients (49.0%) had ≥ 4 positive LN, 327 (26.0%) had tumor size ≥ 5 cm and 727 (57.6%) grade III tumors. 1192 (94.2%) received (neo)adjuvant chemotherapy (1155 with anthracyclines-based regimens) and 97.3% had endocrine therapy (56.1% with aromatase inhibitors). Notably, 33.8% discontinued endocrine therapy (ET) for adverse events. The table reports the survival rates.Table: 132PAfter a median follow up of 6.2 yrsHigh-risk HR+ BCNon-high risk HR+BC5y-IDFS80.9%93.6%10y-IDFS67.6%78.1%5y-DMFS84.4%96.8%10y-DMFS72.2%85.9% Open table in a new tab This RW data showed that patients with high-risk HR+ BC have a considerable risk of relapse and lower event free survival, which highlights the potential benefit of adding new therapies in the adjuvant setting. Rate of treatment discontinuations due to ET-related adverse events underscores the importance of a support system to manage adverse events adequately.