428P - Key landmarks of male advanced breast cancer: Results of the GEICAM/2016-04 study

Background

There are limited data of metastatic breast cancer in male (mMaBC) patients (pts) treated as per routine clinical practice. MaBC is usually diagnosed at an older age and disease stage, so survival rates are lower in comparison to female pts.

Methods

GEICAM/2016-04 is a retrospective observational study with MaBC pts diagnosed from 2000 to 2019. The current analysis is focused on advanced setting: characteristics at diagnosis, BC subtypes at first diagnosis (locally assessed; hormone receptor positive [HR+]/HER2 negative [HER2−], triple negative [TN] [HR−/HER2−], and HER2+ [any HR]), tumour burden, first-line (1L) therapy, and outcomes.

Results

773 pts were included at 51 Spanish sites, 154 (20%) pts had advanced disease (7% de novo mBC, 13% recurrence [stage I 1%, II 6% and III 6%]). Their median age was 66 years. 14 (27%) of 52 pts with genetic testing had BRCA1/2 mutation (mut); BC family history was reported in 27 (52%) of 52 pts tested and 8 (57%) of 14 BRCA1/2 mut pts. BC subtypes: 106 (70%) HR+/HER2−, 23 (15%) HR+/HER2+, 4 (3%) TN (50% de novo mBC), and 21 (14%) unknown. Subtype conversion analysis in 30 pts with paired primary and metastatic tumours: 3 of 24 HR+/HER2− pts changed to 2 TN and 1 HER2+ and, 3 of 6 HR+/HER2+ pts changed to HR+/HER2−. 89 (58%) pts had visceral metastases and 80 (52%) a single metastatic location. Bone was less frequent than visceral location, in recurrent vs de novo mBC pts (P-value<0.05). 145 (94%) pts received 1L-therapy. With a median follow-up of 64 months (mo), HR+/HER2− pts had a median PFS to 1L of 15 mo (95% CI 13−28) and HER2+ pts of 18 mo (95% CI 13−28). There were no significant differences between subtypes, nor stages at diagnosis. A statistically significant difference (P-value<0.05) in PFS favoured ET-containing therapy in HR+/HER2− pts (vs. chemotherapy), no differences were observed in HER2+ pts (n=6). No differences in survival from mMaBC were observed between HR+/HER2− and HR+/HER2+ pts.

Conclusions

These findings are aligned with the already known in female breast cancer, pointing out the high percentage of BRCA1/2 mut pts (even higher than in early MaBC pts) and the conversion rate in HR+/HER2+ subtype. These results need to be confirmed in other series.

Clinical trial identification

NCT03800355.

Editorial acknowledgement

Legal entity responsible for the study

GEICAM Spanish Breast Cancer Group.

Funding

INVI ASS.

Disclosure

N. Martinez: Financial Interests, Personal, Advisory Role: Roche, Lilly, Novartis, Astra-Daichii, Pfizer; Financial Interests, Institutional, Research Funding: Pfizer; Financial Interests, Personal, Other, Travel, Accomodations, Expenses: Pfizer. M. Santisteban Eslava: Financial Interests, Personal, Advisory Board: Roche; Financial Interests, Personal and Institutional, Research Grant: Genentech; Non-Financial Interests, Member: Geicam, Solti, Big. S. Del Barco Berron: Financial Interests, Personal, Invited Speaker: Novartis, GSK. E. Zamora Adelantado: Financial Interests, Personal, Invited Speaker, Review session for medical oncologists: Eisai, Lilly; Financial Interests, Personal, Invited Speaker, Manegement of iCDK toxicities to oncologist nurses.: Novartis; Other, Registration to ESMO Congress 2022 (virtual): Novartis; Other, Registration to: Eisai; Other, Virtual registration to ASCO Congress 2023: Novartis; Other, Registration to SEOM Congress 2023: Lilly; Other, Registration to ESMO Breast Cancer Congress 2023: MSD; Other, Registration to ESMO Congress (Virtual): Roche. V. Iranzo: Financial Interests, Personal, Invited Speaker: Ipsen, Roche, Novartis, Pfizer, Eisai, Daiichi Sankyo, AstraZeneca, Pierre-Fabre, Teva, Seagen; Financial Interests, Personal, Advisory Board: Genomic Health, Roche, Pfizer, Advanced Accelerator Applications, Astra-Zeneca. T. Martos Cardenas: Financial Interests, Personal, Invited Speaker: Pfizer, AstraZeneca, Daiichi Sankyo, Novartis. A.L. Guerrero Zotano: Financial Interests, Personal, Advisory Role: Pfizer, AstraZeneca, Pierre Fabre, Novartis, Exact Science; Financial Interests, Personal, Speaker’s Bureau: Roche, MSD, Novartis, Astrazeneca, Daichii Sankyo, Pierre Fabre; Financial Interests, Institutional, Research Funding: Lilly; Financial Interests, Speaker’s Bureau: Exact Science. A. Urruticoechea: Financial Interests, Personal, Advisory Role: InProTher, Ellipses Pharma; Financial Interests, Personal, Other, Travel, Accommodations, Expenses: Roche/Genentech, Pfizer, Gilead Sciences. All other authors have declared no conflicts of interest.