Analysis of Response Evaluation Criteria in Solid Tumors reduction ratio of primary chemotherapy in unresectable advanced or recurrent colorectal cancer

Response Evaluation Criteria in Solid Tumors (RECIST) is used to assess the objective response of solid tumors to treatment. However, it remains unclear to what extent the response rate assessed by RECIST reflects a reduction of tumor size in multiple organs in patients with unresectable advanced or recurrent colorectal cancer (CRC) with multiple organ metastases. It is also unclear whether the management of liver metastases with systemic chemotherapy in CRC patients with multiple organ metastases improves their prognosis, although surgical resection has been shown to be the most effective treatment approach to CRC cases with liver metastases. A total of 38 CRC patients who underwent systemic chemotherapy in Kyushu Medical Center Hospital between January 2013 and April 2016 were examined. The patients had measurable lesions in multiple organs, including the liver, and did not undergo curative surgery for metastatic lesions after initiation of chemotherapy. The association between the total reduction ratio (TRR) of all lesions and liver lesion reduction ratio (LRR) was retrospectively analyzed. A total of 18 patients (47%) had H3 liver metastases, and the median liver lesion occupancy rate in the sum of the measured lesions with RECIST was 76%. TRR and LRR were strongly correlated, regardless of the volume of the liver metastases. Although a TRR of >30% was significantly associated with improved overall survival (OS), this improvement was not observed in patients with H3 liver metastases. TRR was correlated with LRR and was associated with a better OS. CRC patients with both multiple organ and H3 liver metastases exhibited poor survival, even with a high reduction ratio by chemotherapy.