Chemoprevention of head and neck cancer with retinoids: a negative result.

Objective: To determine whether isotretinoin (or 13-cis-retinoic acid) decreases the risk of second primary cancers in patients previously treated for cure of head and neck squamous cell carcinoma.

Design: Randomized, double-blind, placebo-controlled trial.

Setting: Two head and neck multidisciplinary cancer clinics in university teaching hospitals taking cases from 4 to 5 million people in Queensland, Australia, combined to enter appropriate patients into this trial.