Clinical and Histopathological Risk Factors for Multiple Cutaneous Squamous Cell Carcinomas

Some patients with cutaneous squamous cell carcinoma (cSCC) may suffer from multiple tumors but little is known of the patient- or tumor-related factors associated with multiple cSCCs.

To investigate the proportion of patients having more than 1 cSCC tumor and to explore whether there are factors that associate with multiple cSCC tumors.

Histopathological diagnoses of "cSCC" from patients treated in Pirkanmaa, Finland, between 2006 and 2020, were obtained from the pathology database to identify patients with cSCC and to obtain the number of all diagnosed cSCC tumors. Clinical records were reviewed to collect information on the patients and their tumors.

A total of 1421 patients with 1988 cSCC tumors were identified. One-fifth of the patients (n = 285) had multiple cSCC tumors during the study period. A multivariable-adjusted model showed the patients with multiple cSCCs to be more often men and to have actinic keratosis, Bowen's disease, and basal cell carcinomas (BCCs) more frequently than the patients with a single cSCC. The median time between the index and the second cSCC was 13 (interquartile range 2-34) months and the second tumor appeared at the same location as the index tumor in 71% of the cases. An invasion depth of more than 2 mm was associated with multiple tumors.

Multiple tumors appeared in 20% of the patients with cSCC, and were more common among those with previous or simultaneous premalignant skin lesions and BCCs.