Abstract P5-12-05: Gestation and breast cancer in women with mutations in DNA repair genes: Is there any relationship?

Abstract Introduction: Women carrying mutations in reparative genes frequently ask about the safety of pregnancy or the use of fertility-promoting techniques. The evidence on gestation and breast cancer (BC), specifically in mutated BRCA, provides contradictory results1,3. On the one hand, there are studies that support the protective nature of pregnancy, while others show that gestation is a factor that promotes it1. Likewise, some point to differences in the association according to the type of mutation, BRCA1 or BRCA22. Objectives: To prove whether there is a relationship between pregnancy and BC in patients with mutations in DNA repair genes and to establish a solid knowledge base for counseling these patients in clinical practice. Patients and methods: We conducted an analytical, observational and retrospective study of 259 women with mutations in DNA repair genes, whether they had developed cancer or not, with different gestational histories in the Medical Oncology Service. The genes studied were: BRCA1and2, MUTYH, hMSH2, hMSH6,RAD51C,APC,CHECK2,ATM,PALB2,PTEN,BRIP1,ATM+RAD51D,BRCA1+NTHL1,CDKN2A,TP53,NF1,RAD51D. Results: The proportion of patients who develop cancer in the pregnant group is 46.9%. pregnant women is 46.9%, compared to 37.3% in nulliparous women ((χ²) =1.839, p= 0.171). We observed that the diagnosis of BC occurred before the age of 40 years in 40% of pregnant women, compared to 30% in nulliparous women. Likewise, we observed that from the third pregnancy onwards, the percentage of women suffering from BC is higher, with a peak in the fourth pregnancy (68.8% vs. 31.3%) (p=0.135) and that 51.3% of women whose first pregnancy was before the age of 30 years developed BC, compared to 38.6% in those whose first pregnancy was at a later age (X2=4.16, p=0.041). Finally, we observed that 80% of breast cancers developed after 10 years from the first birth. Conclusions: Considering our results, we cannot affirm that at present there is an association between gestation and BC in women with mutation in genes involved in DNA repair. Table: Cross table between cancer (Yes/No) and pregnancy (Yes/No) Citation Format: María López-herrero lópez, Cristina Morales Estévez, Ana Armenta Triviño, Maria Jose Contreras, Maria Gómez Aguilera, Beatriz Rodriguez Alonso, Ignacio Porras, Juan de la Haba-Rodríguez, Enrique Aranda Aguilar. Gestation and breast cancer in women with mutations in DNA repair genes: Is there any relationship? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-12-05.