The transformation of laryngeal keratosis into invasive carcinoma.

Although 93.0% to 97.0% of all laryngeal carcinomas are diagnosed on the first biopsy, 3.0% to 6.7% of them occur in patients who have what is initially diagnosed as "laryngeal keratosis." To study this phenomenon, we examined data from 1,019 patients with laryngeal keratosis seen between 1962 and 1981. Eleven patients with keratosis and initially undetected cancer at different laryngeal sites were excluded, as were 87 outside referrals for whom no records were available beyond the histologic report. The remaining 921 patients were classified on the basis of the initial histologic findings into groups comprising 604 patients with keratosis without atypia (group 1), 204 patients with mild atypia (group 2), 23 patients with moderate atypia (group 3), and 90 patients with severe atypia (group 4). All 921 were followed for from 5 to 25 years. Invasive carcinoma of the larynx developed in 18 patients from group 1 (3.0%), 15 from group 2 (7.4%), four from group 3 (17.4%), and 25 from group 4 (27.8%). Fifty-seven patients (91.9%) developed invasive carcinoma after less than 10 years but only five (8.1%) did so after 10 years or more.