Advances in molecular biology have improved our understanding of RCC carcinogenesis. As a result, various strategies including immunotherapies and molecular-targeted therapies have been developed to treat patients with localized or metastatic RCC18. Although many potential molecular biomarkers might influence the prognosis and therapeutic decisions of RCC, none are presently available for routine clinical testing owing to the complexity of molecular changes and the lack of validated evidence19. The routine clinical prognostic judgment of RCC is still primarily based on conventional pathological examination and clinicopathologic prognostic factors. Typically, peripheral blood is easy to obtain. Blood analyses, such as white blood cell, lymphocyte, platelet, neutrophil, and monocyte counts, are also frequently used in clinical practice, making them ideal biomarkers to predict the treatment outcomes in cancer patients20. Thus, we assessed the prognostic significance of preoperative LMR in patients with RCC-IVCTT after surgery.
Systemic inflammation is a hallmark of cancer and participates in tumor occurrence and progression21. Many classic markers of systemic inflammation are based on the ratios of circulating white cells, such as LMR, NLR and lymphocyte-to-platelet ratio. LMR has been recently evaluated for its ability to predict the prognosis of various cancers. Xia et al. reported that pretreatment LMR is an independent prognostic factor for OS and metastasis-free survival in RCC patients treated with nephrectomy. Gu et al.22 also demonstrated that decreased pretreatment LMR is associated with poor OS and PFS in patients with metastatic clear cell RCC. However, there are no published data describing the prognostic role of preoperative LMR in patients with RCC-IVCTT who underwent radical nephrectomy and thrombectomy. The present findings revealed the significant correlation of decreased preoperative LMR with clinicopathological features associated with tumor progression. Furthermore, the low preoperative LMR group tended to have decreased PFS and OS. These results remained significant after adjusting for other variables that may have affected our results. Therefore, LMR was an independent prognostic factor in patients with RCC-IVCTT after surgery.
Although radical nephrectomy with IVCTT thrombectomy is the current standard mortality treatment for RCC-IVCTT, this procedure has been associated with high surgical morbidity, ranging from 12.4–46.9%23. Therefore, factors that could predict poor perioperative outcomes should be considered during the presurgical treatment period. The present findings showed that high preoperative LMR is associated with prolonged postoperative hospital stays and increased hemorrhage during surgery, demonstrating that the procedure is more difficult in the high preoperative LMR group than in the low preoperative LMR group. Thus, preoperative LMR may have the potential to predict surgical difficulty and help surgeons make individual perioperative care decisions.
Lymphocytes in the peripheral blood display anti-tumor activity by supporting host defense24. High lymphocyte numbers are significantly associated with favorable clinical outcomes in several types of cancer25–27. High levels of lymphocytic attractant chemokines, such as gamma-interferon inducible protein-10 and monokine induced by gamma-interferon, can predict a favorable prognosis in RCC patients28. A low lymphocyte count might be associated with a immunosuppressive state, indicating a deficient immunologic reaction to tumors29. Monocytes, which comprise 5% of the circulating white blood cells that circulate in the bloodstream, are innate immune cells of mononuclear phagocytes30.Monocytes could differentiate into macrophages or dendritic cells, which are essential in establishing innate and adaptive immune processes. Recently, monocytes have emerged as important mediators in the modulation of tumor progression in various human cancers. The role of macrophages/monocytes in the progression of malignant tumors remains contentious, as different subsets have diverse functions in malignant tumor growth31. Nevertheless, ample evidence indicates that tumor-associated macrophages (TAMs) can inhibit anti-tumor immunity and facilitate tumor progression32. Pushalkar et al33and Yin et al34 revealed that TAMs promote cancer cell invasiveness and metastasis by inducing epithelial-mesenchymal transition, tumor angiogenesis, and immunosuppression. Other studies have shown that once recruited by tumor-secreted attractants to the tumor microenvironment, macrophages can shift to a pro-tumor state (M2-like TAMs) in response to various stimuli, such as IL-10 and tumor necrosis factor β35. Moreover, M2-like TAMs was shown to counteract the efficacy of chemotherapy and radiotherapy through suppression of CD8+ T cell function, contributing to cancer progression and poor prognostic outcomes. Moreover, M2-like TAMs can counteract the efficacy of chemotherapy and radiotherapy by suppressing CD8+ T cell function, contributing to cancer progression and poor prognostic outcomes36. In addition, the clinical prognosis of RCC is poor, as macrophage infiltration facilitates the growth of RCC via angiogenesis37. This collective evidence suggests that monocytes exert pro-tumorous influences and contribute to tumor growth by altering macrophage phenotypes. To enhance the predictive value, LMR, as an alliance of peripheral lymphocytes and monocytes, was found to be an independent prognostic predictor of various cancers.
To predict the prognosis of RCC-IVCTT more accurately, there is an urgent need to find a simple, inexpensive, and reliable clinical tool. The TNM, UISS, and SSIGN prognostic models are well-established prognostic models for localized RCC. Nevertheless, it remains unclear whether preoperative LMR could improve the prediction accuracy in patients with RCC-IVCTT after surgery. Based on a previous study by Gu et al.22, we incorporated preoperative LMR into the TNM, UISS, and SSIGN prognostic models. The adjusted model had better discriminatory ability than the TNM, UISS, and SSIGN models, with an increased predictive accuracy for PFS of 6.9%, 6.8%, and 3.4%, respectively. Moreover, incorporating LMR into the SSIGN model led to an increased predictive accuracy of 6.5%. Therefore, the combination of preoperative LMR and current prognostic models may be used to refine the outcome prediction for patients with RCC-IVCTT after surgery. Intense and stringent postoperative surveillance and consideration of participation in clinical trials may help to improve the survival outcomes of high-risk RCC patients. In the present study, the UISS and SSIGN models were not independent predictors of OS (P > 0.05). This may be because previous studies enrolled patients with all TNM stages of RCC for prognosis prediction13, while our study mainly focused on patients with RCC-IVCTT.
There are some limitations in the present retrospective study. First, the sample size was relatively small. The prognostic value of preoperative LMR in patients with RCC-IVCTT remains to be further confirmed in larger multicenter studies and prospective trials. Second, no established cutoff point for preoperative LMR has been determined in patients with RCC-IVCTT. Although ROC curve analysis was performed to determine the optimal cutoff point in this study, this unaccepted statistical analysis may have affected our results to a certain extent.