Multidisciplinary Treatment, Including Locoregional Chemotherapy, for Merkel-Polyomavirus-Positive Merkel Cell Carcinomas: Perspectives for Patients Exhibiting Oncogenic Alternative Δ exon 6–7 TrkAIII Splicing of Neurotrophin Receptor Tropomyosin-Related Kinase A. This evidence concerns the gene NTRK1 and Merkel cell skin cancer.