Prolonged clinical response with regorafenib administered as second-line therapy in an elderly patient suffering from peritoneal carcinomatosis of colon cancer.

Peritoneal carcinomatosis from colorectal cancer (CRC) has a poor prognosis with median survival and clinical responses that are worse than for other metastatic sites, and even more so in pretreated patients proposed for regorafenib therapy. Thus, patients with these characteristics are a therapeutic challange. The present study reports the case of an 83-year-old woman with diffuse peritoneal carcinomatosis from CRC, RAS-mutated, and treated with second-line therapy with the off-label administration of regorafenib at full dose (160 mg once daily, for the first 21 days of each 4-week cycle), refusing conventional chemotherapy. The patient reported an unexpected clinical response, reduced toxicity, excellent adherence to therapy and remained progression-free for 30 months from the start of treatment. In clinical practice, an earlier use of regorafenib and a different selection of patients could be the subject of future studies.