Malignant transformation of solar keratoses to squamous cell carcinoma.
1689 people aged 40 years and over were examined over a 5-year period to determine the incidence of malignant transformation of solar keratoses. They were seen on 2 consecutive years on 4267 occasions; a total of 21,905 solar keratoses were present on the first visit. A squamous cell carcinoma (SCC) developed within 12 months on 28 of the 4267 occasions. Where accurate mapping of both SCCs and pre-existing solar keratoses was available, it was found that 10/17 (60%) SCCs arose from a lesion diagnosed clinically as a solar keratosis in the previous year and the other 7 (40%) SCCs on what had been clinically normal skin 12 months previously. The risk of malignant transformation of a solar keratosis to SCC within 1 year was less than 1/1000. The cost-effectiveness of treating all solar keratoses to prevent the development of SCC is questionable.
D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D007642:Keratosis / Q000175:diagnosis / Q000209:etiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009790:Occupations; D011446:Prospective Studies; D012306:Risk; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*; D013472:Sunlight / Q000009:adverse effects*; D013997:Time Factors; D014739:Victoria