Risk of another basal cell carcinoma developing after treatment of a basal cell carcinoma

Background: There is an increased risk of new basal cell carcinomas (BCCs) developing in a person who has had a BCC. Objective: This study attempts to define the magnitude of this increased risk. Methods: The charts of 260 white patients with a histologically proven BCC were reviewed for the occurrence of new BCCs. The cumulative 5-year incidence (modified life-table method) for new BCCs developing in these patients was compared with the 5-year incidence in the general white population of the United States. Results: Of the 260 patients, new BCCs developed in 137 within an average of 38.3 months, a 5-year cumulative rate of one or more new BCCs of 45.2%. The yearly risk for new BCCs developing in the study population remained high during the 5-year interval. In the general white population of the United States, the maximal 5-year incidence was calculated to be 5% ( p < 0.005, chi-square test). Conclusion: Patients with a history of BCC require life-long follow-up because of the high probability of new BCCs developing.