Methylation of the retinoic acid receptor β gene, RARB, and that of the checkpoint with forkhead and ring finger gene, CHFR, was associated with tumour stage (RARB: 51·9 per cent for T1–2 versus 33·9 per cent for T3–4, P < 0·001; CHFR: 5·5 per cent for T1–2 versus 12·6 per cent for T3–4, P = 0·005). The gene discussed is RARB; the disease is neoplasm.