Microbial impact on tumorigenesis of heritable cancers proximal to the gut is well documented. Whether the microbiota influences cancers arising from inborn mutations at sites distal to the gut is undetermined. Using two models of heritable cancer, we found the microbiota to be inconsequential for tumor development. However, the type of tumor that develops may be influenced by the microbiota. This work furthers our understanding of the microbial impact on tumor development.