PALB2 and breast cancer: It has also been shown that germline mutations of PALB2, an important breast cancer susceptibility gene, conferred an increasing risk of having contralateral breast cancer (hazard ratio, 2.9, p = 0.006), and another study indicated that among 235 female patients with pathogenic variants, 28 patients had mutations of PALB2, and the bilateral mastectomy rate of these 28 patients was 61%.26, 27, 28