Our findings suggest that most RS-eligible BRCA1/2 and PALB2 PV carriers diagnosed with breast cancer at younger than 50 years of age (RS ≥16: BRCA1 = 89.4%, BRCA2 = 85.3%, PALB2 = 73.4%), and many at age 50 years and older (RS ≥26: BRCA1 = 71.7%, BRCA2 = 44.3%, PALB2 = 37.1%), have results indicating benefit from chemotherapy. This evidence concerns the gene PALB2 and breast cancer.