Risk of skin cancer development in 672 patients affected by actinic keratosis.

BACKGROUND: Actinic keratoses (AKs) are the most common type of keratinocytic lesions worldwide. The skin areas affected by the so-called "field cancerization" harbor mutagenetic risks for the development of squamous cell carcinoma (SCC). METHODS: We retrospectively investigated the histopathological reports and clinical charts of 672 patients affected by multiple AKs, presenting at least 5 years of follow-up. The frequency of non-melanoma skin cancers (NMSC, namely SCC and basal cell carcinoma [BCC]) and malignant melanomas (MMs) in patients affected by multiple AKs were analyzed. RESULTS: More than 40% of patients with a previous diagnosis of multiple AKs developed an NMSC (SCC or BCC), or an MM, during a follow-up period of 5 to 11 years. The risk of developing another skin malignancy appeared to be higher in the age range between 61 and 80 years. The relative risk of developing a BCC and/or an MM in patients with a previous AK diagnosis was found to be 4.52. CONCLUSIONS: The presence of multiple AKs and "field cancerization" seems to be associated with a high risk not only of NMSC such as SCC and BCC, but also of MM. An adequate follow-up is required in these groups of patients.