Case-control study of risk factors in laryngeal cancer.

A case-control study with 100 cases and 100 controls was conducted to test hypothetical risk factors in laryngeal cancer. McNemar's test helped to select 25 variables, 12 of which were indicated by the conditional logistic regression analysis as independently associated with laryngeal cancer. The association was proved to be statistically significant in the case of seven risk factors; smoking more than 10 cigarettes per day (RR = 18.17; 95% CI 1.95-169.76), predominantly tinned food and meat product diet (RR = 2.65; 95% CI 1.02-6.88), long-term work exposure to low temperatures and building, fabric and metal dust (RR = 4.53; 95% CI 1.80-11.37), extended stay in closed space filled with cigarette smoke (RR = 2.67; 95% CI 1.08-6.60), recurrent hoarseness persisting for more than 1 month (RR = 12.68; 95% CI 3.28-49.03), swollen neck lymph nodes over a number of years (RR = 12.81; 95% CI 1.57-104.29). It was inferred that these seven tested variables could represent risk factors in laryngeal cancer.