Introduction/Background PALB2 is located on chromosome 16, it is essential for the function of BRCA2. It is a high-risk gene, although the risk of breast cancer (BC) in carriers is greatly affected by family burden. Overall, a cumulative risk of BC at 70 years of age is estimated at 35%. Pathogenic variants in PALB2 also increase the risk of BC in men, and are associated with an increased risk of pancreatic cancer, and a slight increase in ovarian cancer (OC).

Methodology Retrospective observational study. Review of patients followed in the inherited cancer unit in a single tertiary centre between 1st January 2012 until 31st March 2022. The statistical analysis was carried out using SPSS 22.0.

Results During the indicated period, we followed 459 patients with confirmed genetic mutations that predispose to developing gynaecological cancer. Of the total, 2.2% (10/459) were carriers of PALB2 mutation. Within this cohort of patients, 6/10 (60%) had a family history of BC. 2/10 were diagnosed with a BC at 54 and 36 years old. And other 2/10 with OC at 61 and 49 years old. The histology of BC was invasive ductal carcinoma in both cases. And the histology of OC was high grade serous carcinoma. Surgery treatment was: unilateral mastectomy with homolateral axillary lymphadenectomy, maximal effort cytoreduction in one OC case and interval surgery after neoadjuvant chemotherapy in the other. Adjuvant treatment was needed in all of them: chemotherapy (CT) and radiation therapy (RT) in one BC case, hormone therapy and RT in the other BC case, and CT in both OC cases. Three patients (3/10) underwent prophylactic breast surgery (bilateral nipple sparing mastectomy with immediate reconstruction).

Conclusion Patients carrying PALB2 mutations have a high risk of developing BC and should be followed in specialized hereditary cancer units, in tertiary hospitals.