REToma: a cancer subtype with a shared driver oncogene.

RET (REarranged during Transfection), which encodes a receptor tyrosine kinase for members of the glial cell line-derived neurotrophic factor, plays a role as driver oncogene in a variety of human cancers. Fusion of RET with several partner genes has been detected in papillary thyroid, lung, colorectal, pancreatic and breast cancers, and tyrosine kinase inhibitors (TKIs) for RET (particularly RET-specific inhibitors) show promising therapeutic effects against such cancers. Oncogenic mutations within the extracellular cysteine-rich and intracellular kinase domains of RET drive medullary thyroid carcinogenesis; the same mutations are also observed in a small subset of diverse cancers such as lung, colorectal and breast cancers. Considering the oncogenic nature of RET mutants, lung, colorectal and breast cancers are predicted to respond to RET TKIs in a manner similar to medullary thyroid cancer. In summary, cancers carrying oncogenic RET alterations as a driver mutation could be collectively termed 'REToma' and treated with RET TKIs in a tissue-agnostic manner.