Application of machine learning models in predicting early stone-free rate after flexible ureteroscopic lithotripsy for renal stones / 北京大学学报(医学版)

OBJECTIVE@#To establish predictive models based on random forest and XGBoost machine learning algorithm and to investigate their value in predicting early stone-free rate (SFR) after flexible ureteroscopic lithotripsy (fURL) in patients with renal stones.@*METHODS@#The clinical data of 201 patients with renal stones who underwent fURL were retrospectively investigated. According to the stone-free standard, the patients were divided into stone-free group (SF group) and stone-residual group (SR group). We compared a number of factors including patient age, body mass index (BMI), stone number, stone volume, stone density and hydronephrosis between the two groups. For low calyceal calculi, renal anatomic parameters including infundibular angle (IPA), infundibular width (IW), infundibular length (IL) and pelvic calyceal height (PCH), would be measured. We brought above potential predictive factors into random forest and XGBoost machine learning algorithm respectively to develop two predictive models. The receiver operating characteristic curve (ROC curve) was established in order to test the predictive ability of the model. Clinical data of 71 patients were collected prospectively to validate the predictive models externally.@*RESULTS@#In this study, 201 fURL operations were successfully completed. The one-phase early SFR was 61.2%. We built two predictive models based on random forest and XGBoost machine learning algorithm. The predictive variables' importance scores were obtained. The area under the ROC curve (AUROC) of the two predictive models for early stone clearance status prediction was 0.77. In the study, 71 test samples were used for external validation. The results showed that the total predictive accuracy, predictive specificity and predictive sensitivity of the random forest and XGBoost models were 75.7%, 82.6%, 60.0%, and 81.4%, 87.0%, 68.0%, respectively. The first four predictive variables in importance were stone volume, mean stone density, maximal stone density and BMI in both random forest and XGBoost predictive models.@*CONCLUSION@#The predictive models based on random forest and XGBoost machine learning algorithm can predict postoperative early stone status after fURL for renal stones accurately, which will facilitate preoperative evaluation and clinical decision-making. Stone volume, mean stone density, maximal stone density and BMI may be the important predictive factors affecting early SFR after fURL for renal stones.

Outcomes after transanal endoscopic microsurgery for early rectal cancer and risk factors associated with recurrence / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate outcomes after transanal endoscopic microsurgery (TEM) for early rectal cancer, identify risk factors associated with recurrence, and explore the indication of TEM for rectal cancer.</p><p><b>METHODS</b>Sixty patients with rectal cancer undergoing TEM between June 2006 and June 2009 in the Provincial Qianfoshan Hospital of Shandong University were included in this study and data were retrospectively analyzed.</p><p><b>RESULTS</b>There were 12 patients with pTis rectal cancer, 38 with pT1 and 10 with pT2. All the lesions were excised en bloc by full-thickness TEM. No positive resection margins were reported. The operative time was(65.0 ± 36.5) min. Estimated blood loss was (10.5 ± 5.8) ml and hospital stay was(4.5 ± 2.7) d. No perioperative mortality and complications occurred. The median follow-up was 28.5(range, 12-48) months. No recurrence developed in pTis lesions. There was significant difference in local recurrence rate between pT1 and pT2(2.6% vs. 40.0%, P<0.05). The recurrence rate in lesions larger than 3 cm in diameter(19.0%, 4/21) was significantly higher than that in lesions smaller than 3 cm in diameter (2.6%, 1/39) (P<0.05). Multivariate analysis showed that depth of tumour invasion(T stage) and tumour size were independently associated with recurrence after TEM.</p><p><b>CONCLUSION</b>Local excision by TEM is oncologically safe and effective for pTis and pT1 rectal cancers and early lesions smaller than 3 cm in diameter.</p>