Feasibility of targeted therapies in the adjuvant setting of early breast cancer in men: real-world data from a population-based registry.

BACKGROUND: Following the positive iDFS and OS results of the phase III clinical trials monarchE, NATALEE and OlympiA, new oral anticancer agents (the CDK4/6 inhibitors abemaciclib, ribociclib as well as the PARP inhibitor olaparib) have recently been introduced into the treatment of high-risk early breast cancer (eBC). However, only few male patients were included in these trials (0.4%, 0.6% and 0.3%, respectively). The objective of this real-world analysis was to determine the proportion of male patients with eBC fulfilling the clinical high-risk criteria of above-mentioned trials.

PATIENTS AND METHODS: We conducted a data inquiry and analysis with the Cancer Registry of Baden-Württemberg of men with breast cancer diagnosed between January 1, 2015 and December 31, 2021. Men with eBC were identified and the number of patients at clinical high-risk according to the inclusion criteria of monarchE, NATALEE and OlympiA was assessed.

RESULTS: Of 397 men with eBC, 354 (89.1%) had a HR + /Her2- and 4 (1.0%) a triple-negative subtype. 84 patients (21.2%) met the clinical high-risk criteria according to the monarchE, 189 (47.6%) those according to the NATALEE and 50 (12.6%) those according to the OlympiA trial.

CONCLUSION: In a large real-world sample, more men with eBC are at clinical high risk according to the inclusion criteria of monarchE, NATALEE and OlympiA than would be expected in women. This is most likely due to more advanced stages at initial diagnosis in men. To evaluate whether CDK4/6 and PARP inhibitors improve prognosis also in men should be the topic of future real- world analyses.