In the present study, we demonstrated that the preoperative ANS was an independent risk factor for postoperative complications in patients following radical resection of colon cancer. Furthermore, a prognostic nomogram combined with the ANS and other perioperative risk factors was further constructed and validated to predict postoperative complications. This visible nomogram could be applied as a convenient means allowing more precise risk stratification of postoperative complications for individual patients which may facilitate early clinical decision-making.
Some rencent reports have demonstrated that several systemic inflammatory markers may be predictors of postoperative complications following different major surgeries. (11–14) Specifically, previous studies revealed that various immunenutritional scores or inflammation-based scores, including CAR (C-reactive protein to albumin ratio), NLR, PLR and PNI were associated with short-term outcomes after surgery for colorectal cancer. (21–24) In the present study, the association between ANS and postoperative complications after radical resection of colon cancer was determined. The NLR is a classic systemic inflammation biomarker and can be calculated easily by circulating neutrophils and lymphocytes easily obtained from routine preoperative blood testswithout extra expenses; while hypoalbuminemia, resulting from malnutrition particularly in cancer patients, is correlated with an increased risk of postoperative infectious complications, and the mechanism for this seems to be a composite of impaired healing and impaired immune response. (25, 26) Due to the ANS was combined with albumin and NLR which represented the inflammatory reaction of liver and myeloid/lymphoid tissue, respectively, thence, we chosed the ANS to improve the predictive power of the nomogram predicting postoperative complications after radical resection of colon cancer.
In the present study, the preoperative ANS was determined to be an independent risk factor associated with postoperative complications after radical resection of colon cancer. Furthermore, the C-index of AIC-based multivariable analysis was 0.821 by including the ANS which was higher than removing ANS whose C-index was 0.798. The calibration curve also demonstrated that using ANS could significantly enhance the predictive value of the nomogram for radical resection of colon cancer. As is known to all, albumin is a negative acute-phase protein combined with decreased expression and growed losses within inflammation procedures. In general, hypoalbuminemia means malnutrition in acute and chronically ill patients. Previous studies have also demonstrated that hypoalbuminemia is a significant risk factor in postoperative mortality, morbidities and length of hospital stay in different patients.(27, 28) Although the possible mechanisms between inflammation and short-term poor prognosis remain unknown, our study indicate that preoperative ANS can be utilized as an independent risk factor for postoperative complications after radical resection of colon cancer.
Except for ANS, intraoperative blood transfusion was identified as another independent risk factor for postoperative complications after radical resection of colon cancer in the backward stepwise AIC-based multivariable analysis. Previous study demonstrated that blood transfusion was correlated with an increasing occurrence of postoperative infections around anastomoses, most probably secondary to transfusion-associated immunological suppression.(29–31) In addition, Jannasch et al. indicated that there was a 1.5-fold risk of anastomotic leak with blood transfusion within radical resection of colon cancer, despite without distinguishing of the amount of blood units administrated.(32) On the other hand, hemoglobin is association with perfusion and oxygenation of the anastomotic margins, an indispensable factor for anastomotic healing. Some studies have also demonstrated that a hemoglobin level less than 11 g/dL may increase the risk of anastomotic leak, as explained by a declined ability to supply oxygen to the tissues and subsequent hazard of ischemia.(33, 34) Although blood transfusion may be one of the risk factors for postoperative complications, blood transfusion acted as one of the important components of perioperative fluid management for surgical patients. However, we should strictly grasp the blood transfusion guidelines and avoid unnecessary blood transfusion, thereby reducing the risk of postoperative complications.
Besides, gender, age, duration of surgery, urine output and surgical type were also included in the present nomogram model. The combination of those variables in our nomogram enhanced the predictive value, which further indicated the critical roles of those variables in forecasting the probability of postoperative complications after radical resection of colon cancer.
However, the present study still has several limitations. The first of which is that the statistical models are developed based on a retrospective study in a single center. In this aspect, a future prospective research to verify the outcomes would be meaningful. Lack of validation based on external dataset is another limitation. Thirdly, as surgical manipulation may have significant impact on patients’ short-term outcome, therefore, different surgical groups should be taken into account in the future study.