Preliminary characterization of the skin microbiota in basal cell carcinoma: An exploratory pilot study in Korean patients

Basal cell carcinoma (BCC) is the most common form of skin cancer, with ultraviolet radiation recognized as the primary environmental driver; however, the potential contribution of alterations in the skin microbiota remains incompletely understood, particularly in Asian populations. This exploratory pilot study describes bacterial community patterns in BCC lesions compared with contralateral clinically normal skin in 20 Korean patients. Lesional and contralateral samples were obtained using paired skin swabs and punch biopsies and analyzed by full-length 16S rRNA gene sequencing, with targeted quantitative PCR (qPCR) of the roxP antioxidant gene of Cutibacterium acnes. Given the low-biomass nature of skin samples and the exploratory design, analyses focused on descriptive trends rather than confirmatory inference. Across available samples, C. acnes was the dominant taxon, with a trend toward lower relative abundance in BCC lesions, particularly in biopsy-derived datasets. Microbial evenness appeared higher in lesions than controls. Predictive functional profiling suggested reduced representation of vitamin B6 metabolism pathways in lesions, while qPCR analysis of swab samples showed a trend toward lower roxP/16S rRNA ratios in BCC-associated microbiota. These findings should be interpreted cautiously in light of methodological constraints, including sample heterogeneity, lidocaine exposure prior to biopsy, absence of sequencing-based negative controls, and reliance on predictive functional inference. Overall, this pilot study highlights potential differences in skin bacterial community structure between BCC lesions and contralateral skin in a Korean cohort. Larger, methodologically optimized studies incorporating metagenomic and functional validation will be required to determine whether these microbiota shifts contribute to, or result from, BCC-associated changes in the cutaneous environment.