OCCURRENCE OF CUTANEOUS BASAL-CELL AND SQUAMOUS-CELL MALIGNANCIES AMONG THOSE WITH A PRIOR HISTORY OF SKIN-CANCER

Non-melanoma skin cancer patients are believed to be at high risk of d eveloping new skin malignancies; however, relatively few studies have actually examined this. Non-melanoma skin cancers, although generally not fatal, are responsible for significant morbidity and, if left untr eated, can cause serious disfigurement and, in rare instances, death. Part of the difficulty in studying these tumors is that they are not r outinely followed as rigorously as other cancers, and are excluded fro m most cancer registries. Prior studies have often included patients f rom a single dermatology practice or those treated with one type of th erapy (e.g., Moh's surgery). Some studies did not entail active follow -up of patients but relied on reports to a registry or subsequent visi ts initiated by the patient or their physician. Other studies have bee n based solely on patients with complete follow-up information, exclud ing those who died or were lost to follow-up. Nearly all studies colle cted only a limited amount of information on each patient. In an attem pt to overcome these limitations, we examined subsequent skin cancer o ccurrence among a group of patients followed as part of the Skin Cance r Prevention Study. In the following, we highlight some of the methodo logic issues concerning the study of subsequent basal cell and squamou s cell skin cancer risk, and the contribution of our work, along with that of others, in exploring clinical and etiologic questions pertaini ng to the occurrence of these malignancies.