Adjuvant chemotherapy in pT1ab node-negative triple-negative breast carcinomas: Results of a national multi-institutional retrospective study

International audienceBACKGROUND:Triple-negative breast cancers (TNBCs) are considered as associated with poor outcome, but prognosis of subcentimetric, node-negative disease remains controversial and evidence that adjuvant chemotherapy (CT) is effective in these small tumours remains limited.PATIENTS AND METHODS:Our objective was to investigate the impact of CT on survival in pT1abN0M0 TNBC. Patients were retrospectively identified from a cohort of 22,475 patients who underwent primary surgery in 15 French centres between 1987 and 2013. As rare pathological types may display very particular prognoses in these tumours, we retained only the invasive ductal carcinomas of no special type according to the last World Health Organisation (WHO) classification which is the most common TNBC histological type. End-points were disease-free survival (DFS) and metastasis-free survival (MFS). A propensity score for receiving CT was estimated using a logistic regression including age, tumour size, Scarff Bloom and Richardson (SBR) grade and lymphovascular invasion