Survival outcomes and risk factors of malignant left large bowel obstruction in metastatic left-sided colon cancer patients during chemotherapy: A Multicenter Propensity- Score Analysis

Background Chemotherapy is recommended for metastatic colorectal cancer (mCRC). However, chemotherapy may be interrupted by malignant left-large bowel obstruction (MLLBO). The aim of this study was to investigate the oncologic outcomes and risk factors for MLLBO in metastatic left-sided colon cancer (mLCC) patients undergoing chemotherapy. Methods Three large medical centers in Sichuan province, Southwest of China, took part in this multicenter retrospective cohort study. Consecutive mLCC patients who received chemotherapy from June 2012 to July 2021 at those centers were divided into two groups based on whether MLLBO occurred during chemotherapy. Patients were propensity score matched (PSM) at a ratio of 1:2 into MLLBO and non-MLLBO groups. Univariable and multivariable Cox proportional hazards regression models were used to identify predictors of survival. Results Among 1,638 mLCC patients, 156 were included in the matched cohort. The median overall survival was 37.5 months in the non-MLLBO group and 28.0 months in the MLLBO group (p = 0.018). The corresponding median cancer-specific survival was 39.0 months in the non-MLLBO group and 30.0 months in the MLLBO group (p = 0.02). Multivariable Cox regression analysis showed that MLLBO was independently associated with reduced overall survival (hazard ratio [HR] = 1.473, 95% CI: 1.186-1.812, P < 0.001) and cancer-specific survival (HR = 1.619, 95% CI: 1.391-1.899, P < 0.001). Additionally, tumor length ≥5 cm (P = 0.043) and TTI ≥1.5 cm (P < 0.001) were identified as independent risk factors for MLLBO. Conclusion Patients without MLLBO had a better prognosis than those with MLLBO during chemotherapy. Preventive measures are recommended for mLCC patients at higher risk of developing MLLBO during chemotherapy.