Background and Aims: The coexistence of RAS and BRAF mutations is extremely rare, occurring in approximately 0.05% of patients with metastatic colorectal cancer (mCRC). Starting from a case presentation, this review aims to examine the prevalence, clinical, histopathological and molecular features of tumors with concomitant mutations.

Methods: Case report and systematic review. We performed a systematic literature search in PubMed and EMBASE using the following MeSH terms: “coexistence” OR “concomitant” AND “RAS” AND “BRAF” AND “colorectal cancer” from the inception of the databases onwards.

Results: We present the case of a 53-year-old man diagnosed with metastatic rectal adenocarcinoma with both a KRAS and a BRAF mutation. The review included eleven papers reporting on a total of 30 mCRC cases with concomitant RAS and BRAF mutations. The male/female ratio was 11/5. The average age was 58.5 years. The tumor was located in nine cases on the right colon and in two cases in the left colon. 43.3% of subjects had liver metastases, and 6.6% had lung metastases. Next-generation sequencing (NGS) was used in 36.6% of cases and polymerase chain reaction (PCR) in 16.6% of cases. KRAS mutations were present in 83.3% of patients and NRAS mutations in 16.6% of patients. Survival could be assessed in 10 patients and the median was 21.1 months (about 30% lower than the survival in the general mCRC population).

Conclusion: The results of this systematic review suggest the need to design a cohort study (either prospective or retrospective) to better characterize the patients with concomitant RAS and BRAF mutations and to establish the optimal treatment for this rare situation.


metastatic colorectal cancer, concomitant mutations, RAS, BRAF