Incidence and malignant transformation of glottic precursor lesions in Denmark

Objectives: Glottic precursor lesion (GPL) is a well-known premalignant condition, but the existing knowledge of incidence and malignant potential is based on subpopulation studies. In this first, nationwide study we report data from all verified cases of GPL in Denmark during a 10-year period with focus on incidence and malignant transformation of GPL.Methods: Patients were identified by a search for GPL in the time period from 01.01.2000 to 31.12.2009 using the Danish Pathology Data Base, Patobank, which is a nationwide source of all cyto- and histopathological data obtained in Denmark. Data were validated and supplemented by medical chart review.Results: A 10-year national cohort of 965 patients (median age 60 years, male-female ratio 2:1) with histologically verified GPL was analyzed. The overall malignant transformation rate was 18.3% (mild dysplasia 7.7%, moderate dysplasia 19.8%, severe dysplasia 28.5%, and carcinoma in situ 40.3%) with a median progression time of 29 months. Eighty-eight percent of patients were active or former smokers. A significantly larger proportion of male patients (24.1%) experienced malignant transformation compared to females (6.6%) (p < .001).Conclusion: This nationwide population-based study of GPL patients confirmed a stable incidence of GPL in Denmark from January 2000 to December 2009 and a considerable malignant potential, correlated to the grading of GPL according to the World Health Organization classification of laryngeal precursor lesions from 2005, WHOC2005. The recent update, WHOC2017, of low-grade versus high-grade lesions may thus contain less nuanced prognostic information than WHOC2005.Level of evidence: 2b retrospective cohort study.