In a small case-only study of 23 men with breast cancer, four of whom were carriers of a BRCA1/2 mutation, BRCA1/2 carrier status interacted with history of ever having driven trucks professionally to enhance the risk of developing breast cancer (COR = 25.5; 95% CI = 1.1–1415) [402]. The gene discussed is BRCA1; the disease is breast carcinoma.