[Risk factor analysis on anastomotic leakage after laparoscopic surgery in rectal cancer patient with neoadjuvant therapy and establishment of a nomogram prediction model].

Abstract

Objective: To investigate the risk factors of anastomotic leakage (AL) after laparoscopic surgery in rectal cancer patient with neoadjuvant therapy and construct a nomogram prediction model. Methods: This study was a retrospective case-control study that collected and reviewed the clinicopathological data of 359 patients who underwent laparoscopic surgery from January 2012 to January 2018, including 202 patients from the Department of General Surgery, Nanfang Hospital of Southern Medical University and 157 patients from the Department of Gastrointestinal Surgery of Fujian Provincial Cancer Hospital. Inclusion criteria: (1) age ≥ 18 years old; (2) diagnosis as rectal cancer by biopsy before treatment; (3) distance from tumor to anus within 12 cm; (4) locally advanced stage (T3-T4 or N+) diagnosed by imaging (CT, MRI, PET or ultrasound); (5) standardized neoadjuvant therapy followed by laparoscopic radical operation. Exclusion criteria: (1) previous history of colorectal cancer surgery; (2) short-term or incomplete standardized neoadjuvant therapy; (3) Miles, Hartmann, emergency surgery, palliative resection; (4) conversion to open surgery. Clinicopathological data, including age, gender, body mass index (BMI), preoperative albumin, distance from tumor to anus, operation hospital, American Society of Anesthesiologists score (ASA score), operation time, T stage, N stage, M stage, TNM stage, pathological complete response (pCR) were analyzed with univariate analysis to identify predictors for AL after laparoscopic surgery in rectal cancer patient with neoadjuvant therapy. Then, incorporated predictors of AL, which were screened by multivariate logistic regression, were plotted by the rms package in R software to establish a nomogram model. According to the scale of the nomogram of each risk factor, the total score could be obtained by adding each single score, then the corresponding probability of postoperative AL could be acquired. The area under ROC curve (AUC) was used to evaluate the predictive ability of each risk factor and nomogram on model. AUC > 0.75 indicated that the model had good predictive ability. The Bootstrap method (1000 bootstrapping resamples) was applied as internal verification to show the robustness of the model. The discrimination of the nomogram was determined by calculating the average consistency index (C-index) whose rage was 0.5 to 1.0. Higher C-index indicated better consistency with actual risk. The calibration curve was used to assess the calibration of prediction model. The Hosmer-Lemeshow test yielding a non-significant statistic (P>0.05) suggested no departure from the perfect fit. Results: Of 359 cases, 224 were male, 135 were female, 189 were ≥ 55 years old, 98 had a BMI > 24 kg/m(2), 176 had preoperative albumin ≤ 40 g/L, 128 had distance from tumor to anus ≤ 5 cm, 257 were TNM 0-II stage, 102 were TNM III-IV stage, and 84 achieved pCR after neoadjuvant therapy. The incidence of postoperative AL was 9.5% (34/359). Univariate analysis showed that gender, preoperative albumin and distance from tumor to the anus were associated with postoperative AL (All P<0.05). Multivariate logistic regression analysis revealed that male (OR=2.480, 95% CI: 1.012-6.077, P=0.047), preoperative albumin ≤40 g/L (OR=5.319, 95% CI: 2.106-13.433, P<0.001) and distance from tumor to anus ≤ 5 cm (OR=4.339, 95% CI: 1.990-9.458, P<0.001) were significant independent risk factors for postoperative AL. According to these results, a nomogram prediction model was constructed. The male was for 55 points, the preoperative albumin ≤ 40 g/L was for 100 points, and the distance from tumor to the anus ≤ 5 cm was for 88 points. Adding all the points of each risk factor, the corresponding probability of total score would indicated the morbidity of postoperative AL predicted by this nomogram modal. The AUC of the nomogram was 0.792 (95% CI: 0.729-0.856), and the C-index was 0.792 after internal verification. The calibration curve showed that the predictive results were well correlated with the actual results (P=0.562). Conclusions: Male, preoperative albumin ≤ 40 g/L and distance from tumor to the anus ≤ 5 cm are independent risk factors for AL after laparoscopic surgery in rectal cancer patient with neoadjuvant therapy. The nomogram prediction model is helpful to predict the probability of AL after surgery.