Factors influencing outcome after surgery for Stage IV colorectal cancer

According to the classification system of the Japanese Society for Cancer of the Colon and Rectum, Stage IV colorectal cancer is characterized by distant metastasis, which is defined by four factors: liver metastasis (H factor), metastasis to organs other than the liver (M factor), peritoneal dissemination (P factor), and distant lymph node metastasis (N factor). We conducted this study to investigate the postsurgical prognosis of patients with Stage IV colorectal cancer (CRC), in reference to each of these four factors. We analyzed the medical records of 73 patients who underwent surgery for Stage IV CRC at our hospital between 1991 and 2001. Univariate analysis revealed that P0 or P1 CRC (P < 0.001), absence of the M factor (P = 0.024), well or moderately differentiated adenocarcinoma (P < 0.001), resection of the primary tumor (P < 0.001), and curability B surgery (P < 0.0001) were associated with a better prognosis than other types of Stage IV CRC. Multivariate analysis revealed that tumor differentiation and surgical curability affected cancer-specific survival significantly. Surgery with curative intent should be considered for patients with Stage IV CRC defined by the P1 factor or H factor.