The effect of the synthetic retinoid etretinate on sputum cytology: results from a randomised trial

Laboratory studies, and one previous uncontrolled trial, have suggested that retinoids may reverse bronchial atypia, a putatively premalignant condition. Sputum sampling is a simple, non-invasive method of assessing atypia. Smokers with at least a 15 pack-year history were screened for sputum atypia. One hundred and fifty subjects' were randomised to receive the synthetic retinoid etretinate 25 mg orally or identical placebo daily for 6 months. Compliance was measured by performing pill counts and serum sampling every 2 months for etretinate levels. The outcomes assessed were, improvements in sputum atypia and toxicity. At baseline there was no significant difference between the two groups with respect to gender, smoking history or extent of atypia. Four of 75 subjects on etretinate and six of 75 on placebo dropped out before 6 months. Compliance as measured by pill counts and etretinate levels was high. Eighty-six per cent of subjects on etretinate took 90% or more of their prescribed medication and etretinate was detected in 245 of 264 samples. By contrast etretinate was detected in only six of 266 samples in the control group and probably did not represent true contamination. After 6 months on etretinate there was no difference in the degree of atypia between the two treatment arms. Toxicity was mild in both groups with considerable placebo effect noted. Etretinate, at the dose used in this study, had no impact on sputum atypia as detected by sputum sampling.