A novel nomogram to predict the local tumor progression after microwave ablation in patients with early‐stage hepatocellular carcinoma: A tool in prediction of successful ablation

OBJECTIVES: To develop a nomogram for the local tumor progression (LTP) in patients with early‐stage hepatocellular carcinoma (HCC) after computed tomography‐guided percutaneous microwave ablation (CT‐PMWA) and to assess clinical‐pathologic risk factors for individual LTP estimation. Furthermore, we compared the prognostic predictive ability for LTP between the nomogram and the traditional staging systems. METHODS: This retrospective study was approved by the institutional review board. Five hundred and forty treatment‐naïve patients with HCC according to the Milan criteria, who subsequently underwent CT‐PMWA were reviewed from 2009 to 2019. Baseline characteristics were collected to identify the risk factors for the determination of LTP after CT‐PMWA. The multivariate Cox proportional‐hazards model based on significant prognostic factors of LTP was used to construct the nomogram, which was then assessed for its predictive accuracy using mainly the Harrell's C‐index and time‐dependent area under the curve (tAUC). RESULTS: After a median follow‐up time of 28.7 months, 6.5% (35/540) patients had LTP. The nomogram was developed based on the tumor size, tumor number, Child‐Turcotte‐Pugh (CTP) grade, platelet, and alanine aminotransferase (ALT). The nomogram had good calibration and discriminatory abilities in the training set, with C‐indexes of 0.799 (95% confidence interval (CI): 0.738, 0.860), and tAUCs of 0.844 (CI: 0.728, 0.895), that were greater than those of traditional staging systems. Internal validation with 1000 bootstrap resamples had a good C‐index of 0.735 (CI: 0.648, 0.816). CONCLUSIONS: The nomogram model can be used to predict accurately LTP after CT‐PMWA for early‐stage HCC, as well as to assist physicians during the therapeutic decision‐making process.