Postoperative complications are known to be associated with a poor prognosis in colorectal cancer [17]. We found a postoperative complication rate of 79.8% in LRRC, and the rate of CD ≥ III complications was 38.4%. To avoid postoperative complications, it is important to know the risk factors and provide a presurgical therapeutic intervention to prevent them. We identified two independent risk factors for complications after LRRC surgery in this study: a preoperative PNI < 44.2 and intraoperative blood loss ≥ 2850 mL. These findings indicated that the preoperative nutritional status and surgical invasiveness could be related to severe postoperative complications in patients with LRRC.
The PNI is a simple nutritional index, based on the serum albumin level and the lymphocyte count. It has been associated with perioperative complications in various carcinomas [18, 19]. Albumin is an index of nutritional capacity, and lymphocytes are an index of nutrition and immune capacity. Thus, the PNI reflects nutrition and immune status. Accordingly, patients with low PNIs are expected to have low wound healing ability and low immune function.
One might ask why did severe complications after LRRC surgery show a stronger correlation with PNI than with other inflammatory markers? One explanation might be that the NLR and PLR values after chemotherapy did not reflect the nutrition and immune status correctly. Chemotherapy reduces blood cell counts by suppressing bone marrow activity; therefore, the NLR and PLR might be affected, because they are calculated from blood cell counts. In the present study, preoperative chemotherapy for LRRC was performed in 62 patients (62.6%). As a result, the NLR and PLR might be less sensitive to severe postoperative complications than expected. Another potential explanation might be the limited accuracy of our blood test equipment. Because we could not assess CRP levels below 0.04, CRP levels less than 0.04 were treated as 0.04 in this study. Therefore, we could not accurately assess the CAR and LCR values, which required the CRP level.
The relationship between blood loss and postoperative complications was previously reported in colorectal cancer surgery [20, 21]. Heavy bleeding can change the hemodynamics and impair organs, particularly the kidneys and liver, and it also affects coagulation. These changes can lead to several postoperative complications, such as VTE and bleeding. It has been reported that VTE and bleeding at or greater than CD grade III after curative resection of primary colorectal cancer occurs at rates of 0 to 0.16% and 0.2 to 0.81%, respectively [22–24]. Compared with these data, in the present study, VTE and bleeding events more frequently occurred (Table 4).
Some previous studies have reported that preoperative nutritional interventions were effective for postoperative outcomes in various types of cancer. Indeed, preoperative exercise and nutritional support improved the postoperative outcome in patients with gastric cancer [25]. Despite concern that nutritional interventions might delay surgery, preoperative treatments are often performed in patients with LRRC; therefore, there should be sufficient time to improve the patient’s nutritional status.
We previously reported that laparoscopic surgery was safe and useful for LRRC [26]. The magnifying effect of the laparoscope is highly effective in surgery for pelvic organ cancers, where it is difficult to expand the field of view. Additionally, the carbon dioxide insufflation used to create a working space in the abdomen can provide pressure, which reduces bleeding. Indeed, patients with rectal cancer that underwent laparoscopic surgery had less intraoperative blood loss than patients that underwent a laparotomy [27, 28]. Although laparoscopic surgery for LRRC could potentially prevent intraoperative and postoperative complications, the number of patients that underwent laparoscopic surgery in this study was insufficient to assess the correlation between the surgical approach and complications.
This study had some limitations. First, the study was retrospective, and data were from a single center. Second, the cohort was relatively small. Although 99 patients represented a relatively large cohort in clinical research for LRRC, it was insufficient to clarify the risk factors for postoperative complications.