Abstract YO9
Case summary
Introduction
BRAF V600E-mutated metastatic colorectal cancer (mCRC) patients are present in 8-12% of mCRC and their prognosis is poor. According to BEACON CRC study, encorafenib(E)+binimetinib(B)+cetuximab(C) or E+C resulted in longer overall survival than standard chemotherapy in 2nd line treatment. Ocular symptoms have been reported as side effects, but serous retinal detachment is not common. We report a case in which treatment modification was made after the onset of serous retinal detachment and the patient was able to continue treatment safely.
Case presentation
A 59-year-old woman with an Eastern Cooperative Oncology Group Performance Status of 0 presented with post-surgical peritoneal dissemination recurrence of Stage IIIb BRAF V600E-mutated descending colon cancer. She was treated with capecitabine and oxaliplatin as adjuvant therapy. During the adjuvant therapy, the tumor marker elevated, and computed tomography confirmed peritoneal dissemination. FOLFOXIRI+bevacizumab was administered as 1st line treatment, and the tumor marker was elevated within four months. E+B+C was started as 2nd line treatment. Although tumor markers gradually decreased, bilateral visual loss due to serous retinal detachment developed after three months. The ocular symptoms improved within four days solely by suspending the E+B+C, without any specific interventions for the serous retinal detachment. After a two-week treatment break due to rising tumor markers, E+B+C was resumed. However, bilateral visual loss recurred just two days after restarting the treatment, so the treatment was stopped again. Five days later, the treatment was switched to E+C and tumor progression was not shown for about 10 weeks without any adverse events, including serous retinal detachment.
Conclusion
We present a case of BRAF V600E-mutated mCRC that was successfully treated with E+C following the occurrence of serous retinal detachment associated with E+B+C. This case highlights the potential for treatment modification to manage side effects and continue effective cancer therapy.