Preoperative prediction of transanal specimen extraction feasibility in colorectal cancer: development and internal validation of a prediction model

Introduction. Although Natural Orifice Specimen Extraction Surgery (NOSES) is increasingly used in colorectal surgery, objective criteria for preoperative selection for transanal specimen extraction remain lacking. This study aimed to develop and internally validate a preoperative model of technical feasibility based on experimental specimen testing.
Materials and methods. We performed a retrospective analysis of prospectively collected data from a consecutive single-center cohort of 105 patients with colorectal cancer. Each resected specimen was sequentially tested ex vivo for passage through elastic rings with internal diameters of 3, 4, and 5 cm. Successful passage through the 4-cm ring was the primary endpoint. A logistic regression model was developed using preoperative characteristics. Internal validation included 1000 bootstrap resamples and 10-fold cross-validation; discrimination, calibration, and clinical utility by decision curve analysis were assessed.
Results. Passage rates were 18/105 (17.1%), 58/105 (55,2 %), and 86/105 (81,9 %) for the 3-, 4-, and 5-cm rings, respectively. Passage through the 4-cm ring was associated with actual NOSES performance: 35/37 (94,6 %) versus 23/68 (33,8 %) after conventional laparoscopy (χ²=33.4; p<0.001). The model included transverse tumor size, body mass index, and tumor location. The apparent AUC was 0,846, the optimism-corrected AUC was 0,829, and the 10-fold cross-validated AUC was 0,827. Decision curve analysis demonstrated potential clinical utility across threshold probabilities of approximately 0,20–0,80.
Conclusion. The standardized ex vivo model provided a reproducible endpoint for preoperative prediction of transanal specimen extraction feasibility. After external validation, the model may support individualized planning of NOSES procedures.

1. Huang B., Liu M., Gao W., Tang J., Zhu Z., Chen L. et al. Nomogram for predicting the feasibility of natural orifice specimen extraction after laparoscopic rectal resection. J Gastroenterol Hepatol., 2021, no 36, pp. 1803–1811. https://doi.org/10.1111/jgh.15333

2. Zhang Z.Y., Zhu Z., Zhang Y., Ni L., Lu B. A nomogram for predicting feasibility of laparoscopic anterior resection with transrectal specimen extraction (NOSES) in patients with upper rectal cancer. BMC Surg., 2021, no 21, pp. 296. https://doi.org/10.1186/s12893-021-01290-4

3. Guan X., Liu Z., Longo A., Cai J.C., Chen W.T.L., Chen L.C. et al. International consensus on natural orifice specimen extraction surgery (NOSES) for colorectal cancer. Gastroenterol Rep (Oxf), 2019, no 7, pp. 24–31. https://doi.org/10.1093/gastro/goy055

4. Liu Z., Guan X., Zhang M., Hu X., Yang M., Bai J. et al. International guideline on natural orifice specimen extraction surgery (NOSES) for colorectal cancer (2023 version). Holist Integr Oncol., 2023, no 2, pp. 9. https://doi.org/10.1007/s44178-023-00034-z

5. Collins G.S., Reitsma J.B., Altman D.G., Moons K.G.M. Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD): the TRIPOD statement. BMJ, 2015, no 350, pp. g7594. https://doi.org/10.1136/bmj.g7594

6. Vickers A.J., Elkin E.B. Decision curve analysis: a novel method for evaluating prediction models. Med Decis Making., 2006, no 26, pp. 565–574. https://doi.org/10.1177/0272989X06295361

7. Efetov S.K., Cao Yu., Khlusov D.I., Zubayraeva A.A., Krasnov Ya.P. Short-term outcomes of colorectal cancer treatment after natural orifice specimen extraction surgery (NOSES) and with conventional laparoscopy. Moscow Surgical Journal, 2024, no 4, pp. 116–125. (In Russ.) https://doi.org/10.17238/2072-3180-2024-4-116-125