In BC samples, promoter hypermethylation was the most frequently detected in PRKCB (86/111, 77%), RASSF1 (79/115, 69%), ADAMTS12 (67/107, 63%), APC (61/115, 53%), and RUNX3 (46/114, 40%) genes and significantly differentiated BC from the control group (0%, 14%, 7%, 0%, and 0%, respectively; all p < 0.0001). The gene discussed is RASSF1; the disease is breast cancer.