Basal Cell Carcinoma May Be Associated With Staphylococcus Dysbiosis

There is growing evidence that a dysbiosis of the skin microbiome has an impact on carcinogenesis in cutaneous squamous cell carcinoma. However, the role of the microbiome in basal cell carcinoma (BCC) remains unclear due to limited, inconsistent, ex vivo studies. Here, we analysed the skin microbiome of patients with BCC, including the tumour lesion as well as perilesional skin from the same subject. Skin swabs from BCC and perilesional skin were taken prior to tumour surgery. After DNA extraction, we used a metabarcoding approach based on 16S rRNA gene amplicon sequencing to analyse the cutaneous bacterial communities. In total, 63 patients with BCC were included for analysis. Most tumour lesions were located on sun-exposed, sebaceous areas such as the nose, cheeks, and forehead. The genera Corynebacterium, Cutibacterium, and Staphylococcus predominated both in BCC and perilesional skin. However, the microbiome of BCC was reduced in overall bacterial richness, with a significant overabundance of amplicon sequence variants (ASV) assigned to the genus Staphylococcus, resulting in a reduced complexity in microbial networks. The dominating ASV assigned to Staphylococcus was also detected in perilesional skin regions, indicating that the microbial dysbiosis in BCC affected regions is caused by natural members of the healthy skin microbiome. The BCC microbiome is characterised by microbial dysbiosis, reflected by a reduced overall bacterial richness, fewer microbe-microbe interactions and a significant over-representation of Staphylococcus species compared with perilesional skin. Further long-read metagenomics and cultivation-based studies are needed to identify Staphylococcus species driving dysbiosis.