BRCA1 and breast cancer: Data on treatment and chemotherapy receipt in PALB2 carriers who develop breast cancer remains sparse, in large part because of the more recent discovery and characterization of PALB2 as a breast cancer susceptibility gene and the relative rarity of pathogenic variants in PALB2 - seen in only 0.2–0.5% of invasive breast cancers [19, 36] - compared to BRCA1/2 [4, 14, 37].