Detection of rat sarcoma virus (RAS) and B rapidly accelerated fibrosarcoma (BRAF) mutations is critical for selecting an appropriate treatment for metastatic colorectal cancer (mCRC). Although RAS and BRAF V600E mutations are traditionally mutually exclusive, they occasionally co-occur. The concurrent occurrence of RAS and BRAF V600E mutations is rare, with an incidence of < 0.001-0.05% in CRC. Treatment outcomes for cases involving concurrent occurrence of these mutations remain unclear, with reported cases exhibiting a poor prognosis of approximately 1 year. Moreover, reports on the long-term survival of patients with unresectable mCRC with concurrent mutations are lacking. The present study reports a rare case of long-term survival of over 39 months in a patient with mCRC harboring both RAS and BRAF V600E mutations, where chemotherapy alone was effective without surgical resection of the primary or metastatic lesions.
Kitagawa et al. (Thu,) studied this question.