Risk of developing a subsequent nonmelanoma skin cancer in patients with ahistory of nonmelanoma skin cancer - A critical review of the literature and meta-analysis

Objective: To assess the risk of developing a basal cell carcinoma (BCC), a nd/or a squamous cell carcinoma (SCC), and/or Bowen disease (SCC in situ) a fter a nonmelanoma skin cancer (NMSC) of a specific type. Data Sources: Four electronic databases were searched from January 1, 1966, to October 21, 1999. Study Selection: We included all studies published in English, identified b y standard search strategies, that provided original data quantifying the r isk of an NMSC among persons with a previous NMSC. Data Extraction: For each study and separate histological type of index ski n tumor and subsequent skin tumor (SCC, BCC, NMSC, or Bowen disease), we de termined the 3-year cumulative risk and the incidence rate of second tumors per 100 000 person-years. In cases where more than 1 study was assessing t he risk of one specific tumor type after another, we undertook a formal met aanalysis, We compared the incidence of a subsequent SCC after an index SCC and of a subsequent BCC after an index BCC with the incidence of the first occurrence of such tumors in the comparable general population. Data Synthesis: We identified and reviewed 17 studies that included data fo r 26 tumor combinations. Overall, the 3-year cumulative risk of a subsequen t SCC after an index SCC is 18%, at least a 10-fold increase in incidence c ompared with the incidence of first tumors in a comparable general populati on. For BCCs, the 3-year cumulative risk is 44%, also at least a 10-fold in crease in incidence compared with the rate in a comparable general populati on. The risk of developing a BCC in patients with a prior SCC is about equa l to that risk among persons with a prior BCC, but the risk of developing a n SCC in patients with a prior BCC is low (6%). Conclusions: Although these studies vary in their study type, location, and biases, their results are consistent. The risk of developing a subsequent skin cancer of a specific type depends on the type of prior NMSC and number of prior skin tumors of that type. Based on these findings, followup strat egies for patients with BCC and SCC are suggested.