Left-sided laterality of Merkel cell carcinoma in a German population: more than just sun exposure

Background Lateral distribution of cancer has been observed previously. Most evident is this laterality in ultraviolet (UV)-induced skin cancer, based on an unequally distributed UV exposure. Objectives The aim of this study was to explore whether patients from Germany also show asymmetrical lateral distribution of Merkel cell carcinoma (MCC). Methods In total, 115 patients with MCC were studied for laterality of the primary tumour. Correlation of clinical variables with lateral distribution of MCC was investigated as well. Results In 64/115 (55.7%) patients, primary tumours were present on the left side, in 37/115 (32.2%) on the right side, and in 14/115 (12.2%) in the midline ( P