Evaluation of quality control procedures in an oesophageal cancer cohort study in Anyang, China.

We wished to evaluate the efficiency of internal quality control procedures of a cohort study investigating human papilloma virus (HPV) infection as a key exposure factor in oesophageal cancer in Anyang, China. This was done by testing 2395 environmental/equipment swab and mock quality control samples from 14 loci on sample collection equipment for human β-globin and HPV DNA. Human β-globin was present in 3.88% of these samples but no HPV DNA was detected. There was no evidence of HPV DNA contamination in the sample collection or processing under the rigorous quality control in our ongoing cohort study. The study results indicated that use of disposable appliances, rigorous environmental cleaning and a high standard of sterilisation of reusable instruments are important in contamination prevention.