This study investigated the relationship between POCs and OS and RFS after radical gastrectomy for advanced gastric cancer. POCs can prolong hospital stay, and increase cost and postoperative mortality. Studies have shown that POCs can reduce the long-term survival outcome of colorectal cancer[16-18]; the same trend has also been observed in gastric cancer[9, 19, 20].
In this study, we use C-D classification to classify POCs; this system has been regarded as a classical classification method and has been used to classify a variety of POCs [6, 15]. It has also been used to classify POCs of gastric cancer [21, 22]. The cohort was divided into two groups according to the presence of complications. Because the baseline characteristics of patients between the two groups were not comparable, we used PSM to reduce potential confounding factors and selection bias.
The present study showed that POCs were related to poor long-term survival outcomes. To evaluate the relationship between complication grade and survival outcome, we further analyzed the impact of C-D grade complications and severe complications on survival outcome. We found that grade complications had a negative effect on 5-year OS and RFS, but the results were not statistically significant, in contrast with a previous study[23]. Another subgroup analysis showed that severe complications reduced OS and RFS in patients with severe complications; this difference was statistically significant. Further subgroup analysis showed that severe complications reduced RFS in patients with severe complications compared with grade II complications. At the same time, there was a trend of negative impact on OS, but the results did not reach statistical significance (P > 0.05).
Because of the negative impact of POCs on survival outcome, it is necessary to understand the risk factors and take intervening measures. We carried out single- and multi-factor analyses in the whole cohort of in this study. Multivariate analysis showed that age over 50, combined resection, and comorbid diseases were independent risk factors for POCs. Many studies have shown that there is a relationship between advanced age and the occurrence of POCs[24, 25], which is consistent with our research. Old age will lead to a decrease in the physiological function of various organs, deterioration of nutritional status, and a decrease of anesthetic tolerance, which may be related to the increase of POCs. Therefore, in the perioperative management of patients, more attention should be paid to elderly patients.
A number of studies have shown that combined resection is associated with an increase in POCs[24, 26]; our study came to the same conclusion. Combined organ resection can prolong the operation time and increase the scope of surgical injury, which may increase POCs compared with gastrectomy alone. Previous studies have shown that gastrectomy combined with splenectomy or pancreatectomy increases the incidence of POCs and does not improve survival[27-29]. In addition, studies have shown that combined resection may negatively affect the recurrence-free survival of patients[30]. Therefore, more caution should be taken in deciding whether to perform multiple organ resection.
In terms of comorbidities, many studies have shown that comorbidities increase POCs [31-33], which is consistent with our results. This may be related to the fact that co-disease can reduce the patient's respiratory and cardiac reserves. In addition, studies have shown that diabetes is associated with infectious complications [34, 35]. Therefore, appropriate perioperative management of patients with comorbid diseases is necessary.
A large number of studies have indicated that adjuvant chemotherapy can significantly improve the survival outcome of patients with advanced gastric cancer [36-38]. In our study, the chemotherapy data of the two groups were similar after PSM. As a result, the potential effect of adjuvant chemotherapy on survival outcome was eliminated to the greatest extent.
Thus far, the mechanism by which complications lead to poor survival outcomes is unclear. The generally accepted explanation is that the inflammatory microenvironment can promote tumor development, while complications can lead to a severe inflammatory response, which suppresses the patient's immune system and promotes tumor recurrence and metastasis[12, 13].
There were some limitations of this study. First, this study was a single-center retrospective study. Second, the operation was performed by multiple groups of physicians, and the influence of surgical experience on the outcome of the operation could not be ruled out[31]. Finally, PSM could not rule out all deviations; there may be other variables that affect surgical outcomes and survival outcomes that were not included in the study.