These results indicate that: 1) homozygous brca2 mutation increases tumor development in zebrafish, similar to humans with germline biallellic BRCA2 mutations, and 2) homozygous brca2 mutation enhances carcinogenesis in tp53+/m zebrafish, supporting previous work that indicates a collaborative relationship between BRCA2 and TP53 in human carcinogenesis. This evidence concerns the gene BRCA2 and neoplasm.