A large number of studies have found that serum albumin and SII play a critical role in the occurrence, development and prognosis of tumors. In this study, we divided the patients into two groups: high albumin (SII) group and low albumin (SII) group. Finally, we found that serum albumin and SII could predict the prognosis of RC after curative resection, and serum albumin and SII were independent risk factors for OS in RC patients.
TNM staging system occupies the central role in prognosis and therefore treatment allocation. However, quantifiable risk measures cannot be provided and the accuracy was affected by tumor heterogeneity. Therefore, it is necessary to find a novel biomarker to identify patients with poor prognosis and guide the personalized treatment. The important role of inflammation in tumorigenesis, progression and metastasis has become as a hot topic in medical research. Because the immune and nutritional status of the system contributed to the inflammatory response, multiple studies focused on the predictive values of biochemical indices related to the immune and nutritional status in cancer patients[20, 21].
SII can accurately provide measures of the systemic inflammation, which is calculated based on neutrophil, lymphocyte and platelet counts. Patients with an elevated SII usually have thrombocytopenia, neutrophilia or lymphopenia, indicating an elevated inflammatory status and weak immune response. Neutrophils can stimulate premalignant epithelial cell to enhance cancer cell invasion and release cytokines such as vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β) and platelet derived growth factor (PDGF) to promote tumor proliferation and angiogenesis[22, 23]. Neutrophils can assist cancer cells with evading immune surveillance. Several studies revealed that platelets have the ability of interacting with cancer cells and facilitate tumor metastasis through various pathways[25, 26]. Activated T cells and other lymphocytes contribute to the immune response and inhibit tumor cell proliferation, and thus a lower lymphocyte count can lead to the easier escape of tumor cells from immune surveillance.
Serum albumin was found negatively associated with OS in this study. The level of serum albumin cannot accurately reflect nutritional status but the negative relationship with postoperative complications might affect the postoperative inflammatory status. A recent study also showed that serum albumin can protect the tissues against inflammatory injury. Several studies concluded that serum albumin can be regarded as an independent prognostic biomarker for tumors[30, 31].
Several limitations should be noted in this study. First, inherent selection biases cannot be avoided because of the retrospective nature of this study. Second, inaccurate data recording and medication might affect the quality of blood-circulating cell counts. Third, several patients might receive additional postoperative treatments to improve the prognosis. Therefore, further multicenter or prospective studies are warranted to validate these results.
In conclusion, SII and serum albumin were feasible and promising biomarkers for prognosis in stage II/III rectal cancer. Our established nomogram model can successfully identify patients with high risk of poor prognosis, which can help clinical decision making and potentially provide benefits for clinicians and selected patients.