Multiple Basal Cell Carcinomas. Timeline and Underlying Risk Factors.

Introduction: Between 29% and 53% of the patients who develop basal cell carcinoma (BCC) will develop new BCCs.

Objectives: Current objectives are to analyze the proportion and basic characteristics of patients who develop BCC> 1, to delineate the concept of multiple BCC (mBCC) and be able to identify the factors associated with its development, and analyze its timeframe.

Patients and method: We conducted a retrospective observational study including all patients diagnosed with sporadic BCC from January 1^st, 2014 through December 31^st, 2014 at a tertiary referral center. Data included dates of BCCs, gender, age and histology of the first BCC, and the presence of BCC> 1 at the initial appointment (cluster⁺). mBCC was defined as a patient who developed a series of BCCs> the 75^th percentile of the series.

Results: A total of 758 patients (51.2% men), were included. After a median follow-up of 100 months, 52.8% of the patients developed BCC> 1. The 75^th percentile of the number of BCCs was 3. Factors associated to mBCCs included being cluster⁺ (OR, 5.6; 95%CI, 3.2 - 9.7), being men (OR, 3.1; 95%CI, 2.0 - 4.8) and diagnosed with the first BCC between ages of 50 and 80 years (OR, 2.1; 95%CI, 1.3 - 3.5). After 5 years, 54% of patients exhibiting these 3 factors developed mBCC. The estimated median time to mBCC was 38.00 months (95%CI, 0 - 79.71).

Conclusions: A quarter of patients who Exhibit 1 BCC eventually develop 4 or more BCCs. Analyzing routine parameters may help identify individuals at a higher risk of developing mBCC and predict its timeframe.