Curative metastasectomy in a patient with colon cancer harboring BRAF V600E mutation and mismatch repair deficiency – a case study.

Introduction Both BRAF V600E mutation and mismatch repair deficiency bear prognostic and predictive relevance in metastatic colorectal cancer, yet impact of simultaneous occurrence of both factors on prognosis is under-investigated. Aim Although retrospective studies support localised therapies for oligometastatic CRC in the general population, data for tumours harbouring both alterations are scarce. Case study In 2013, a 66-year-old female underwent radical resection for pT3 N0 distal sigmoid adenocarcinoma. Five months later she was diagnosed with oligometastatic recurrence in the right ovary. In 2014 the woman underwent hysterectomy and bilateral adnexectomy. Histopathology of the resected material confirmed adenocarcinoma metastasis in the right ovary. As the radicality of the resection was uncertain, the patient received 12 cycles of FOLFIRI chemotherapy after which the treatment was suspended due to no evidence of the disease. The follow-up imaging showed no signs of recurrence. A retrospective testing of tumor samples from metastasectomy revealed a BRAF V600E mutation and loss of MLH1, PMS2 expression indicating dMMR. Results and discussion Recently emerging data indicate at better prognosis in metastatic colorectal cancer with coexisting BRAF V600E mutation and dMMR as compared to cases with either of these biomarkers. The literature on the outcomes of metastatic resection in population with both alterations is scarce. The patient described here is an example of favourable outcome, with over 10-year survival after local treatment of colorectal metastases with aforementioned molecular profile. Conclusions Metastasis resection, should be further investigated in colorectal cancers harbouring high risk molecular alterations.