Abstract P2-09-03: Spectrum, prevalence and clinical outcomes of germline mutations in PALB2 genes in 16501 unselected BRCA1/2-negative breast cancer patients: A multi-center analysis

Abstract

Abstract Background: PALB2 (Partner and Localizer of BRCA2) is a breast cancer predisposition gene, which plays a critical role in homologous recombination via interacting with BRCA1/2 and RAD51 when DNA break. However, the clinical relevance of PALB2 germline mutations in Chinese breast cancer patients remains unknown. We attempted to illustrate the full prevalence and spectrum of PALB2 germline mutations in Chinese breast cancer population, and to investigate the clinical outcomes of PALB2 germline mutations. Patients and methods: A total of 21216 unselected breast cancer patients were enrolled from multiple clinical centers in China. After evaluation of the DNA quality and clinical information, 16501 eligible BRCA1/2-negative breast cancer patients were analyzed. A group of 5890 Chinese women without cancer was enrolled as healthy controls. PALB2 screening was based on next-generation sequencing, by screening complete coding sequence and intron-exon boundaries of PALB2. Clinical information was synchronously collected. Results: The 79 PALB2 deleterious germline mutations included 25 nonsense mutations, 47 frameshift mutations, and 7 splicing mutations. The hotspot region for PALB2 mutations was exon4. A total of 41 novel mutations were identified in PALB2. Among the 16501 BRCA1/2-negative breast cancer patients and 5890 healthy women, PALB2 deleterious mutation carriers account for 0.97% (n=160) and 0.19% (n=11) separately. PALB2 mutations were significantly associated with increased breast cancer risk (OR: 5.23, 95% CI 2.89-9.49; P<0.0001), and especially in women aged 30 or younger (OR: 11.97, 95% CI 3.76-34.39; P<0.0001). PALB2 mutation carriers were significantly more likely to be triple negative breast cancers and have bigger tumors, positive axillary lymph nodes, bilateral breast cancers, family history of breast and/or ovarian cancer and family history of any other cancer, than noncarriers. Conclusions: The PALB2 mutations confer a moderately increased breast cancer risk in women, but relatively highly increased breast cancer risk in those aged 30 or younger. PALB2 mutation status is associated with distinct clinical characteristics in breast cancer. Key words:PALB2, breast cancer, germline mutations, next-generation sequencing Citation Format: Jiaojiao Zhou, Honglian Wang, Fangmeng Fu, Zhanwen Li, Yun Liu, Qingjian Feng, Weizhu Wu, Hongxia Wang, Chuan Wang, Yiding Chen. Spectrum, prevalence and clinical outcomes of germline mutations in PALB2 genes in 16501 unselected BRCA1/2-negative breast cancer patients: A multi-center analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-09-03.