1815O - Breastfeeding after breast cancer in young BRCA carriers: Results from an international cohort study

Background

Pregnancy after breast cancer (BC) diagnosis and treatment is safe for patients (pts) carrying germline BRCA pathogenic or likely pathogenic variant. No data so far are available on feasibility and safety of breastfeeding in BRCA carriers.

Methods

This was an international, multicenter, hospital-based, retrospective cohort study including BRCA carriers diagnosed with stage I-III invasive BC at age 40 years or younger between January 2000 and December 2020 (NCT03673306). Pts that delivered a child after BC, were divided into two groups: women who breastfed after delivery and those who did not. Locoregional and contralateral BC recurrences, disease-free survival (DFS) and overall survival (OS) were compared among the two groups.

Results

Among 4732 pts included in the study from 78 centers worldwide, 659 had a pregnancy after BC diagnosis, of whom 474 delivered a child. After delivery, 110 (23.2%) pts breastfed (median duration 5 months), 68 (14.4%) did not breastfeed, 225 (47.5%) underwent bilateral risk-reducing mastectomy before delivery (thus were unable to breastfeed) and 71 (15.0%) had unknown breastfeeding status. Compared to pts in the no breastfeeding group (n=68), those in the breastfeeding group (n=110) were more frequently nulliparous at the time of BC diagnosis (61.8% vs 45.6%, p=0.026) and did not report prior smoking habit (71.8% vs 57.4%, p=0.019). After a median follow up of 7.0 (IQR 3.6-10.5) years after delivery, no difference in cumulative incidence of locoregional and/or contralateral BC events between the breastfeeding (n=110) and no breastfeeding (n=68) groups was observed (adjusted sHR=1.08, 95%CI 0.57-2.06, p=0.82). Similarly, no impact of breastfeeding on DFS (adjusted HR=0.83, 95%CI 0.49-1.41, p=0.49) nor OS (9 OS events in patients that breastfed and 3 in those that did not breastfeed) was observed.

Conclusions

Our study provides the first evidence on the safety of breastfeeding after BC in young BRCA carriers. Our data suggest that breastfeeding is feasible and safe with no difference in locoregional recurrence or second primary BC events, emphasizing the possibility of achieving a balance between maternal and infant needs without compromising oncological safety.

Clinical trial identification

NCT03673306.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Italian Association for Cancer Research (AIRC).

Disclosure

E. Blondeaux: Financial Interests, Personal, Invited Speaker: Eli Lilly; Financial Interests, Institutional, Research Grant, Research grant to my Institution for a research project: Gilead Science. E. Mariamidze: Financial Interests, Personal, Advisory Board, Metastatic breast cancer advisory board -CDK4/6 inhibitors incorporation into the Georgian healthcare system: Novartis; Financial Interests, Personal, Advisory Board, Pembrolizumab initiation and registering in Georgia: MSD; Financial Interests, Personal, Invited Speaker, Olaparib and its modern uses: AstraZeneca; Financial Interests, Personal, Other, Sponsored my flight to ESMO 2023: Servier; Financial Interests, Institutional, Other, Georgian School of oncology yearly conference co-sponsorship 2024: Roche; Financial Interests, Personal and Institutional, Research Grant, ICF funded my ESMO CLinical unit Visit Fellowship -2024 Genoa, Italy: ICF; Non-Financial Interests, Member of Board of Directors, President: Georgian school of oncology; Non-Financial Interests, Other, co-writer of GBCI: WHO; Non-Financial Interests, Member, ESO Ambassador till 2022: ESO; Non-Financial Interests, Member, Media and communication advisor for the group: Georgian group of young oncologists; Non-Financial Interests, Member, member: ASCO; Non-Financial Interests, Member, Fellow: ESCO; Non-Financial Interests, Other, Scientific advisor: City cancer Challenge -Tbilisi; Non-Financial Interests, Leadership Role, President and founder of Georgian school of oncology: Georgian school of oncology; Non-Financial Interests, Member, since 2022: SITC. R. Bernstein Molho: Financial Interests, Other, travel funding: Pfizer; Financial Interests, Speaker, Consultant, Advisor: Novartis, AstraZeneca. A. Ferrari: Financial Interests, Advisory Board: AstraZeneca; Financial Interests, Other: AstraZeneca. S. Linn: Financial Interests, Institutional, Research Funding: AstraZeneca, Eurocept Plaza, Roche, Genentech, Gilead Science, GSK, Novartis, Agendia; Financial Interests, Institutional, Advisory Role: AstraZeneca; Financial Interests, Institutional, Other: Daiichi Sankyo; Financial Interests, Other: Daiichi Sankyo; Financial Interests, Proprietary Information, Patent: Patent. H.J. Kim: Financial Interests, Other: Korea Health Technology R&D Project. E. Agostinetto: Financial Interests, Personal, Invited Speaker: Eli Lilly, AstraZeneca; Financial Interests, Personal, Writing Engagement: Sandoz; Financial Interests, Institutional, Advisory Board: AstraZeneca; Financial Interests, Institutional, Research Grant: Gilead. S. Paluch-Shimon: Financial Interests, Institutional, Advisory Board, Advisory board, invited speaker, honoraria, travel: Roche; Financial Interests, Institutional, Other, Advisory board invited speaker honoraria: Pfizer, Novartis, AstraZeneca; Financial Interests, Institutional, Advisory Board, Advisory board invited speaker honoraria: Exact sciences, Eli Lilly; Financial Interests, Institutional, Other, Advisory board, speaker's bureau, consultancy: Medison; Financial Interests, Institutional, Advisory Board, Advisory board, speaker's bureau: MSD; Financial Interests, Institutional, Advisory Board: Gilead; Financial Interests, Personal and Institutional, Research Grant, Research grant for an RFP independent research put out by SPCC and Pfizer: SPCC (Shared Progress in Cancer Care). A. Toss: Financial Interests, Personal, Invited Speaker: Eli Lilly, Novartis, Pfizer, Gilead; Financial Interests, Personal, Advisory Board: MSD, AstraZeneca, Pfizer, Eli Lilly, Seagen, Novartis; Financial Interests, Personal, Other, Travel Grant: Daiichi Sankyo, Gilead; Non-Financial Interests, Member: AIOM. A. Di Meglio: Financial Interests, Personal, Advisory Board: Kephren, Medycis, Techspert. J. Balmaña: Financial Interests, Personal, Invited Speaker: AstraZeneca; Financial Interests, Institutional, Other, Educational programs: AstraZeneca -MSD; Financial Interests, Institutional, Steering Committee Member: AstraZeneca; Financial Interests, Institutional, Local PI: MedSir. K.R. Rodriguez-Wallberg: Financial Interests, Institutional, Research Funding: Novo Nordisk, Merck, Ferring Pharmaceuticals; Financial Interests, Advisory Role: Swedish Ministry of Health; Financial Interests, Speaker, Consultant, Advisor: Ferring Pharmaceuticals, Roche, Pfizer, Organon, Merck. H.A. Azim Jr: Financial Interests, Full or part-time Employment: Emergence Therapeutics. A.H. Partridge: Financial Interests, Institutional, Advisory Board: Breast Cancer Research Foundation, Susan G. Komen. M. Lambertini: Financial Interests, Personal, Advisory Board: Roche, AstraZeneca, Lilly, Novartis, Pfizer, Exact Sciences, MSD, Seagen, Gilead, Menarini, Pierre Fabre; Financial Interests, Personal, Invited Speaker: Takeda, Sandoz, Ipsen, Libbs, Knight, Daiichi Sankyo, Lilly, Pfizer, Novartis, Roche, AstraZeneca, Menarini, Gilead; Financial Interests, Personal, Other, Travel grant to attend ASCO 2022: Gilead; Financial Interests, Personal, Other, Travel grant to attend ASCO 2023 and ASCO 2024: Daiichi Sankyo; Financial Interests, Personal, Other, Travel grant to attend SABCS 2023: Roche; Financial Interests, Institutional, Coordinating PI, 2-year research grant paid to my Institution: Gilead; Non-Financial Interests, Leadership Role, Chair of the ESMO Young Oncologists Committee from 01/2023 to 12/2024: ESMO; Non-Financial Interests, Member of Board of Directors, Member of the national council of the Italian Association of Medical Oncology (AIOM): AIOM. All other authors have declared no conflicts of interest.