Basal cell and squamous cell carcinomas are important risk factors for cutaneous malignant melanoma. Screening implications.

BACKGROUND: This study was designed to determine the risk of developing malignant melanoma (MM) in patients with a history of basal cell and/or squamous cell skin cancer (BCC/SCC) and to determine whether surveillance efforts can be directed toward these patients for the detection of early MMs.
METHODS: The study cohort was followed by annual total cutaneous examination (TCE). Controls consisted of individuals from the United States population matched for age, sex, and length of follow-up. The anatomic locations of the study cohorts' newly diagnosed MMs were plotted on an anatomic chart. The setting was a private dermatology practice. Two hundred, ninety consecutive white patients with a history of BCC/SCC but with no personal or family history of MM were followed by annual TCEs. The main outcome measures were the relative risk of developing MM and their prognosis.
RESULTS: Ten of the 290 patients developed an MM within an average of 109 months of follow-up (range, 3-17 years). All MMs were less than 0.70 mm in Breslow thickness and 80% occurred on usually clothed cutaneous sites. The expected number of MMs in the control population was 0.59 (P = 0.006), resulting in a relative risk of 17.
CONCLUSION: Patients with BCC/SCC skin cancer are at substantial increased risk for developing MM. Regular and life-long surveillance TCE is an inexpensive and effective method for detecting curable MMs in such patients.