[Environmental and occupational risk factors in keratosis of the larynx].

Laryngeal keratosis may frequently precede the appearance of carcinoma of the larynx which might well indicate that these diseases have a common denominator. A retrospective study of 120 subjects with laryngeal keratosis was examined. The intention of the Authors was to verify whether the principle risk factors involved in the appearance of laryngeal carcinoma were the same as those implicated in laryngeal keratosis formation. Sex age, work activity, cigarette smoke, alcohol consumption and vocal chord abuse were considered. Laryngeal keratosis takes keratosis with dysplasia as well as keratosis without. A link between these two types of keratosis and cancer was sought. In particular, the possibility that a persistent action of the mentioned risk factors could cause laryngeal dysplasia-free keratosis to change into dysplastic lesions and subsequently into cancer was investigated. A case-control study was performed in order to analyze the importance of work activity. Results were statistically significant (P < 0.001). The Cramer V2 calculation demonstrated a clear correlation between the number of cigarettes smoked and the appearance of dysplasia (V2 = 0.117; P < 0.005). Results showed a clearly different behaviour between sexes. The number of males was much higher than females as was the age at which keratosis appeared greater in males. The fact that the average age in which keratosis appeared preceded the appearance of laryngeal cancer by ten years indicates that this interrum is sufficient for keratosis with dysplasia to be transformed into cancer (due to the continued action of the mentioned etiologic factors, mainly referred to cigarette smoke). In our data analysis, no correlation was demonstrated between keratosis without dysplasia and cancer.