Correspondence re: Zheng et al, Haplotype of two variants in p16 (CDKN2/MTS-1/INK4a) exon 3 and risk of squamous cell carcinoma of the head and neck: a case-control study. 11: 640-645, 2002. Cancer Epidemiol Biomarkers Prev. 2003 Jan; 12(1):71; author reply 72.