Composite endpoint for liver and colon simultaneous surgery: a proposed approach to reduce sample size of future clinical trials.

[BACKGROUND] With expanding indications for resection of colorectal liver metastasis (CRLM), simultaneous resections for primary colon cancer (CC) with synchronous colorectal liver metastases (sCRLM) has increased. sCRLM remains debated, however, and only a handful, often underpowered, trials have evaluated this approach. We sought to develop a composite postoperative endpoint (composite endpoint for liver and colorectal simultaneous surgery [CELCSS]) combining colon- and liver-specific complications to reduce sample size requirements in future prospective randomized clinical trials.

[METHODS] Patients who underwent simultaneous resection for CC and sCRLM between 2012 and 2021 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. CELCSS components were selected using univariable logistic regression. Associations among CELCSS, prolonged length of stay (LOS), and 30-day mortality were assessed. Sample size estimates were calculated for CELCSS and its individual components. Separate training and internal validation cohorts were used for model development and testing.

[RESULTS] Among 1591 patients in the training cohort, 24.3% (n = 386) had a positive CELCSS. Components included postoperative bleeding (6.5%), colon anastomotic leak (15.4%), reoperation (4.8%), bile leak (4.1%), and posthepatectomy liver failure (3.5%). CELCSS-positive patients more frequently underwent major resection (34.5% vs 18.6%; P <.001), but there was no difference regarding American Society of Anesthesiology classification or receipt of neoadjuvant therapy (P >.5). CELCSS demonstrated good predictive performance for prolonged LOS (area under the curve [AUC], 0.71 training; 0.72 testing) and 30-day mortality (AUC, 0.70 training; 0.71 testing). Of note, CELCSS reduced the required sample size by 41.4% to 88.5% compared with individual complications.

[CONCLUSION] CELCSS is a strong predictor of outcomes and may be used as a postoperative endpoint to improve clinical trial feasibility by reducing required sample size.