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Abstract This retrospective cohort study aimed to identify baseline patient characteristics involving modifiable lifestyle factors that are associated with the development of colorectal adenomas, and establish and validate a nomogram for risk predictions among high-risk populations with negative index colonoscopy. A total of 83,076 participants who underwent an index colonoscopy at the Tianjin Union Medical Center between 2004 and 2019 were collected. According to meticulous inclusion and exclusion criteria, 249 subjects were enrolled and categorized into the primary and validation cohorts. Based on the primary cohort, we utilized the LASSO-Cox regression and the univariate/multivariate Cox proportional hazards (Cox-PH) regression parallelly to select variables, and incorporated selected variables into two nomogram models established using the multivariate Cox-PH regression. Comparison of the Akaike information criterion and the area under the receiver operating characteristic curve of the two models demonstrated that the nomogram model constituted by four covariates retained by the LASSO-Cox regression, including baseline age, body mass index, physical activity and family history of colorectal cancer (CRC) in first-degree relatives, performed better at predicting adenoma-free survival probabilities. Further validation including the concordance index, calibration plots, decision curve analysis and Kaplan–Meier survival curves also revealed good predictive accuracy, discriminating ability, clinical utility and risk stratification capacity of the nomogram model. Our nomogram will assist high-risk individuals with negative index colonoscopy to prevent colorectal adenoma occurrence and CRC morbidity with improved cost-effectiveness.

Abstract We evaluate the prognostic value of chemotherapy and other prognostic factors on overall survival among colon patients with deficient mismatch repair (dMMR), and determine the optimum time to start chemotherapy after surgery. Data of 306 colon cancer patients with dMMR who received radical surgery were collected from three Chinese centers between August 2012 and January 2018. Overall survival (OS) was assessed with the Kaplan–Meier method and log-rank. Cox regression analysis were used to assess influencing prognosis factors. The median follow-up time for all patients was 45.0 months (range, 1.0–100). There was a nonsignificant OS benefit from chemotherapy for patients with stage I and stage II disease, including high-risk stage II disease (log-rank p: 0.386, 0.779, 0.921), and a significant OS benefit for patients with stage III and stage IV disease for receiving post-operation chemotherapy (log-rank p = 0.002, 0.019). Stage III patients benefitted from chemotherapy regimens that contained oxaliplatin (log-rank p = 0.004), and Starting chemotherapy with oxaliplatin treatment earlier resulted in better outcomes (95% CI 0.013–0.857; p = 0.035). Chemotherapy regimens containing oxaliplatin can prolong the survival time of stage III and IV dMMR colon cancer patients. This beneficial manifestation was more pronounced after starting chemotherapy treatment early post operation. High risk stage II dMMR colon patients including T4N0M0 cannot benefit from chemotherapy.