Somatic Mutations and Genetic Heterogeneity at the CDKN1B Locus in Small Intestinal Neuroendocrine Tumors. - Crona J; Gustavsson T; Norlén O; Edfeldt K; Åkerström T; Westin G; Hellman P; Björklund P; Stålberg P (Annals of surgical oncology, 2015)