Meri Övermark, Sari Koskenmies, Sari Pitkänen
DOI: 10.2340/00015555-2175

Squamous cell carcinoma in situ is an intra-epidermal malignancy of the skin with potential to progress to invasive carcinoma. Commonly used treatments are surgical excision, cryotherapy, photodynamic therapy, laser ablation, curettage with cautery, radiotherapy, topical 5-fluorouracil, and topical imiquimod. The efficacies of these different treatment modalities are compared in this retrospective study of 239 patients with squamous cell carcinoma in situ diagnosed and treated at our hospital during a period of one year. A total of 263 histologically confirmed in situ lesions were followed up for approximately 8 years. The overall recurrence rate was 6.5%. Surgical excision had the lowest recurrence rate, at 0.8%. Recurrence rates with the less-invasive treatment modalities were markedly higher; cryotherapy 4.7% and photodynamic therapy 18%. Of all recurrences, 65% were carcinoma in situ and 35% squamous cell carcinomas. Twenty-three patients had actinic keratosis in the area treated, but these were not counted as recurrences. In conclusion, excisional surgery is the gold standard treatment for squamous cell carcinoma in situ, although it has limitations. Less invasive methods may sometimes be preferred.