A case of an elderly patient with high-grade colorectal cancer in poor general condition who showed near complete response to chemotherapy and achieved long-term survival

INTRODUCTION: Chemotherapy is difficult to administer in patients with poor performance status (PS), advanced metastatic lesion, and unresectable colon cancer. We report herein our experience of a patient who showed complete response to chemotherapy and marked PS improvement. The patient presented with the following adverse factors poor PS, advanced progression of metastatic lesions, advanced unresectable colorectal cancer with severe stricture, and old age. PRESENTATION OF CASE: The patient was an 80-year-old male diagnosed with occlusive cancer of the descending colon with multiple metastases in the liver, Stage Ⅳb (National Comprehensive Cancer Network guidelines version 2. 2018). A 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) + panitumumab (Pmab) regimen was successfully administered and led to decreased tumor marker levels; oral intake also became possible. Additional examinations showed that the primary lesion and distant metastatic lesions had almost disappeared; the patient had achieved a near complete response (CR). Currently, 35 cycles of mFOLFOX6＋Pmab have been administered, and his near CR has been maintained for 32 months. DISCUSSION: Best supportive care (BSC) is the recommended option for elderly patients with advanced unresectable colon cancer. This is the first case in which an elderly patient with poor PS and advanced unresectable colorectal cancer was treated with combination chemotherapy of mFOLFOX6 + Pmab. CONCLUSION: Although the use of chemotherapy for elderly with advanced unresectable colorectal cancer or those with poor PS is limited, this case shows that systemic chemotherapy is now an option for such cases previously managed with BSC.