WORK IN DRY-CLEANING AND THE INCIDENCE OF CANCER OF THE ORAL CAVITY, LARYNX, AND ESOPHAGUS

Objectives-To investigate whether employment in dry cleaning, and pote ntial exposure to perchloroethylene (PCE), were associated with increa sed risk of carcinoma of the oral cavity and pharynx, larynx, oesophag us, and gastric cardia. Methods-Two population based case-control stud ies were carried out. There were 491 cases of carcinoma of the oral ca vity and pharynx, 235 of the larynx, and 404 of the oesophagus and gas tric cardia. 724 controls were selected by random digit dialing. Perso nal interviews ascertained information on lifetime job histories, ciga rette use, alcohol consumption, and other potential risk factors. The probability and level of exposure to PCE were estimated from the scien tific literature. Results-People who worked in dry cleaning tended to consume less alcohol and cigarettes than the general population. The a djusted odds ratio (OR) associated with ever having worked in dry clea ning was 1.6 (95% confidence interval (95% CI) = 0.6 to 4.4) for all c ancer types together. The strongest associations were with laryngeal ( OR 2.7; 95% CI 0.6 to 10.9) and oesophageal squamous cell carcinomas ( OR 3.6; 95% CI 0.5 to 27.0). For laryngeal cancer, the relative risk i ncreased with number of years employed in the dry cleaning industry (P = 0.14. The two cases of oesophageal squamous cell carcinomas had wor ked in dry cleaning for only a short time. Analyses of subsites showed higher risks for supraglottic laryngeal cancer (OR 5.7; 95% CI 1.0 to 32.1) and cancer of the tongue (OR 2.3; 95% CI 0.4 to 12.6). Analyses of exposure to PCE yielded similar results. Conclusions-These finding s could easily be explained by chance; nevertheless, they are consiste nt with previous reports of excess risk of oesophageal, laryngeal, and tongue cancer, and suggest that previous studies of dry cleaners that could not control for alcohol and cigarette use may have underestimat ed the relative risks of such cancers.