Real-world evidence of the management and prognosis of young women (⩽40 years) with metastatic breast cancer.

Background: Breast cancer (BC) in young women merits a specific approach given the associated fertility, genetic and psychosocial issues. metastatic breast cancer (MBC) in young women is an even more serious condition, with limited data available.

Methods: We evaluated management of women aged ⩽40 years with MBC in a real-life national multicentre cohort of 22,463 patients treated between 2008 and 2016 (NCT0327531).

[Not Available].

The emergence of a new tumor entity called HER2-low breast cancer leads us to reconsider therapeutic indications in patients whose tumors were usually considered as luminal or triple negative. The development of antibody-drug conjugates (ADCs) allows using HER2 as a vector of a cytoxic drug with significant clinical efficacy in breast cancer with low HER2 expression. Trastuzumab deruxtecan monotherapy is currently evaluated in phase III trials in HER2-low patients, but also in combination in earlier phase studies.