Clinical Practice and Prognosis of Stage IV Colorectal Cancer

Purpose: The aim of the study was to examine actual practice for patients with stage IV colorectal cancer and to investigate the clinical validity of the subclassifications of M factor in the 9th edition of the Japanese Classification of Colorectal Carcinoma from the perspective of prognosis prediction. Materials and Methods: The subjects were consecutive patients diagnosed with stage IV colorectal cancer between 2008 and 2015 at all designated cancer hospitals in Fukushima prefecture, Japan. Patients with unknown outcomes and untraceable cases were excluded. Result: A total of 1,187 patients were enrolled in the study. The median observation period was 18.6 months [interquartile range: 7.5–32.9] and 878 (73.9%) patients had a fatal event. The percentage of metastatic sites was 69.0% for liver, 26.0% for lung, 28.7% for peritoneal dissemination, 24.4% for extra-regional lymph nodes, and 7.8% for other sites. Patients underwent primary tumor resection in 67.3% of cases, distant lesion resection in 18.5%, chemotherapy in 56.4%, and best supportive care in 15.7%. The median overall survival for cases with M classification M1a, M1b, M1c1 and M1c2 was 25.0, 19.6, 21.3 and 12.1 months, respectively. Conclusion: A prefecture-based cohort study showed the descriptive statistics and prognosis of patients with stage IV colorectal cancer. The M subclassification was found to have a certain validity to predict prognosis.