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Background: It was a difficult question to identify candidates who would benefit most from adjuvant chemotherapy in stage II colon cancer because of the paucity of relevant conclusive clinical trial results. We aimed to assess if mucinous adenocarcinoma (MUA) could be an indicator for the efficacy of adjuvant chemotherapy in stage II colon cancer. Methods: Using SEER * Stat software V.8.3.5, eligible patients were then recruited from the SEER database. A χ 2 test was applied to compare the distribution of different categorical variables between nonmucinous adenocarcinoma (NMUA) and MUA groups. We then used the Kaplan-Meier method to analyze overall survival (OS) of different histological types in stage II colon cancer, and the log-rank test was then used to assess the OS differences. The Cox proportional regression risk models were also built in our analyses to eliminate potential crossed bias from other prognostic factors. Results: A total of 50,065 patients diagnosed with stage II colon cancer were recruited from the SEER database from 2004 to 2011; all the patients were divided into two groups, including NMUA (n = 44,785) and MUA (n = 5,280). The Cox analysis of the histological type indicated that the survival difference between MUA and NMUA failed to reach statistical significance in stage II colon cancer (P = 0.360). In NMUA, patients treated with adjuvant chemotherapy were independently associated with 37.2% decreased risk of overall mortality compared with those not [hazard ratio (HR) = 0.628, 95% confidence interval (CI) = 0.601-1.656, P < 0.001]; in MUA, the number increased to 41.5% (HR = 0.585, 95% CI = 0.515-0.665, P < 0.001). Conclusions: Our study showed that the survival difference between MUA and NMUA failed to reach statistical significance in stage II colon cancer. More importantly, our study had provided the first evidence that chemotherapy would offer higher survival improvement in MUA compared with NMUA in stage II colon cancer; mucinous histology might be an indicator for enhanced survival benefit of chemotherapy in stage II colon cancer.

Background The aim of this study was to evaluate the survival benefit of palliative primary tumor resection in colorectal cancer (CRC) patients with unresectable metastases. Material/Methods Clinicopathological characteristics of eligible patients who underwent surgery to remove the primary tumor and those who did not between 2004 and 2013 were compared. We also evaluated the association between survival and different clinicopathologic characteristics in metastatic CRC. Results The percentage of patients undergoing surgical resection of the primary tumor was higher during the earlier years and trended toward less use of surgery in later years. Palliative primary tumor resection was strongly associated with better cause-specific survival (hazard ratio=0.403, 95% confidence interval=0.389 to 0.417, P <0.001). Conclusions We added new strong evidence supporting the survival benefit of palliative resection, which should be confirmed in future randomized controlled trials.