Role of Systemic Inflammatory Response Markers in Urothelial Carcinoma

Urothelial carcinoma (UC) can occur in various parts of the urinary tract and occurs in different stages and grades. The disease recurs frequently and is monitored through a series of invasive tests, such as cystoscopy or ureteroscopy, over the lifetime of an individual. Although many researchers have attempted to stratify the risks of UC, with the majority being based on cancer characteristics and host factors such as performance status, a risk classification system has yet to be fully developed. Cancer affects various parts of the body through the systemic immune response, including changes in hormones, the number and ratio of white blood cells and platelets, and C-reactive protein (CRP) or albumin levels under the influence of neuroendocrine metabolism, hematopoietic function, and protein and energy metabolism, respectively. Herein, we reviewed various systemic inflammatory response markers (SIRs) related to UC, including CRP, albumin-globulin ratio, albumin, Glasgow prognostic score (GPS), modified GPS, neutrophil-lymphocyte ratio, and platelet-lymphocyte ratio. Our aim was to summarize the role of various SIRs in the treatment of patients with UC.


INTRODUCTION
Urothelial carcinoma (UC) is the fourth most common cancer (1). The cancer is classified based on the site of occurrence as bladder UC (BC) and upper urinary tract UC (UTUC) (1)(2)(3)(4). BC accounts for 90-95% of all UCs, (1)(2)(3)(4) and is the fourth most common cancer among men in the United States, ranking eighth in terms of mortality (4). UC can occur in various parts of the urinary tract and in different stages and grades (2)(3)(4). Most UCs start in the bladder, and 75% of the patients are initially diagnosed with non-muscle invasive bladder cancer (NMIBC) (3,4). Endoscopic surgery, intravesical therapy, and immunotherapy can be performed for the treatment of NMIBC (3). A combination of radical cystectomy (RC), radiation therapy (RT), chemotherapy, and immunotherapy among other treatments have been considered in the standard management of MIBC (2). UTUC demonstrates twice as many pyelocalyx as ureters. More than 60% of the patients have been reported to present with invasive cancer at the time of diagnosis and 15-25% have BC (4). Radical nephroureterectomy (RNU) is the standard treatment of UTUC. A 22-47% recurrence rate of the cancer has been reported in the bladder in contrast to 2-6% in the opposite upper tract (4). Local and distant metastases are associated with a poor prognosis despite the availability of various treatment options (2)(3)(4). A study reported that the 5-years relative survival rate of patients with BC, diagnosed from 2009 to 2015, was ∼77%, with the occurrence of regional and distant metastases in 38 and 5% of the cases, respectively (1). In contrast, the upper tract variant is a relatively rare disease that accounts for 5-10% of all UCs (4). Considering the high relapse rate, the cost of treatment of BC from diagnosis to death, with repeated surgeries and investigations, is the highest among all UCs (2)(3)(4). Appropriate risk stratification and prediction of prognosis are important to determine the necessary treatment protocols based on the characteristics of UC (2)(3)(4). Accordingly, several studies have assessed the role of systemic inflammatory response markers (SIRs) in the prediction of the progression and prognosis of UC. C-reactive protein (CRP), albumin, albuminglobulin ratio (AGR), Glasgow prognostic score (GPS), modified GPS (mGPS), neutrophil-lymphocyte ratio (NLR), and plateletlymphocyte ratio (PLR) have been studied as potential prognostic factors. Herein, we reviewed studies on different SIRs for the diagnosis and treatment of UC.

SIR MARKERS IN CANCER
Cancer progression and prognosis are affected by a variety of factors. Representative parameters in the treatment of cancers are the characteristics of the tumor associated with prognosis. These include the pathological variant, stratified grade and stage, and the imaging stage, which are considered in the measurement of disease progression. However, in addition to these characteristics, status of the patient, including performance status, degree of systemic inflammatory response, muscle mass, and weight status (sarcopenia or cachexia) are also important parameters to be considered. Inflammation plays an important role in the development and progression of cancers as well as in the patients' response to therapy (5). Tumors consist of various types of inflammatory and immune cells (6), which can activate immune cells to produce cytokines, chemokines, growth factors, and prostaglandins (6,7). The inflammatory microenvironment is an essential component of tumorigenesis since most cancers trigger an inflammatory response by building a pro-tumorigenic microenvironment (6,8). The resultant inflammation affects the host immune response to the tumor (6,8). Potential SIRrelated biomarkers in cancer patients include as CRP, NLR, PLR, albumin and GPS.
Level of CRP increases blood circulation in various immunologically mediated inflammatory conditions, including trauma, infection, surgery, burns, allergic reactions, and cancer (9). CRP is primarily synthesized in the liver and is a major component of the innate immune system. It is involved in the initial immunity during infection and in the process of cell death (10). CRP binds to phosphocholine on the surface of damaged and foreign cells and bacteria, activating phagocytosis by macrophages (10). The normal concentration of CRP in healthy adults is between 0.8 and 3.0 mg/L. However, the level of this protein increases during the acute phase of inflammation (10). Depending on the cause, levels of CRP increase to over 50-100 mg/L in 4-6 h and have also been reported to increase over 1000-fold (10). The concentration of CRP is typically maintained in the range of 2-10 mg/L in individuals with chronic inflammation (10).
It is known that secretion of CRP is primarily regulated by IL-6; however, its mechanism has not been fully elucidated.
There is lack of clarity on whether elevation of CRP is related to the inflammatory factors released by the tumor or due to a compromised host immune response. Although there is no clear evidence of the diagnostic or etiological role of CRP in cancer, several studies have reported higher levels of this protein in cancer patients than in healthy individuals (11). Moreover, high baseline levels and specific single nucleotide polymorphisms of CRP have been previously associated with an increased risk of cancer (11). Many recent studies have reported an association between high CRP levels and poor prognosis as well as progressive disease in patients with a variety of cancers, including lung, kidney, colorectal, breast, and ovarian cancers (11).
NLR, another marker of reactions to inflammatory conditions. An absolute NLR ratio has not yet been defined owing to the lack of clarity of the association between high NLR and poor survival in cancer patients. In general, neutrophils provide rapid defense against microorganisms in the infected area during a superficial infection (12). Similarly, in cancers, neutrophils are displaced around tumor cells in response to cytokines and chemical attractants to participate in the initial inflammatory response (12). They recruit CD8+ T cells and promote an anti-tumor response by inducing the production of cytokines, such as TNF-α or IL-12 (12). In contrast, several phenotypes of neutrophil exist, which can promote the formation of tumors via their involvement in immunosuppression mediated by TGF-β (12). Neutrophils stimulated with G-CSF were found to improve the growth of circulating tumor cells in metastatic sites and were involved in angiogenesis caused by cancer (12). Many studies have been published recently on the role of NLR in patients with UC (12). A high NLR was reported to be associated with poor prognosis in cancer patients (12).
Albumin, another marker of reactions to inflammatory conditions. Serum albumin and globulin are the major components of blood plasma (13). Albumin is predominantly produced by the liver. Globulins are produced by the liver as well as the immune system. The main function of albumin is to regulate the volume of blood by maintaining the colloid pressure of blood (13). Infections, burns, liver disease, nephrotic syndrome, and malignant tumors decrease serum albumin levels (13). Normal serum albumin levels range from 3.5 to 5 g/dL and that of serum globulin are 2.6-4.6 g/dL (13). The association between albumin levels and the prognosis of patients has been reported in various cancers, including ovarian, colorectal, and lung cancers, in addition to UC (14). Globulin is composed of various pro-inflammatory proteins such as complement components and immunoglobulins and plays an important role in immunity and inflammation (14). Levels of globulin increase in patients with chronic inflammation or cancer. Albumin and globulin are associated with immune responses in cancer patients as well as the nutritional status (14). Low albumin levels reflect a decline in the status of nutrients, which is common in cancer patients, and is known to interfere with immune mechanisms such as humoral and cellular immunity and phagocytic function (14). Hypoalbuminemia in cancer patients has been reported to result from a reduction in albumin synthesis mediated by secretion of pro-inflammatory cytokines, increased catabolism, and cachexia (14). Increased vascular permeability in these patients also reduces blood albumin levels due to redistribution of the protein from the intravascular to the interstitial areas (14).
Inflammatory cytokines or chemokines are responsible for the activation of platelets (15). Activated platelets induce leukocytes to accumulate in inflamed regions (15). Platelets interact with leukocytes and induce a bidirectional cell activation process, wherein the platelets activate leukocytes, and various leukocytederived molecules activate platelets (15). Activated platelets stimulate neutrophils, which in turn release chromatin (15). Chromatin further recruits and activates platelets (15). Cancer cells in the bloodstream induce platelet-mediated recognition (16). Platelets are amplified by a variety of immune cells, cell products, cell surface receptors, and extracellular factors (16). Under certain circumstances, the interaction between cancer cells and platelets can suppress the recognition or removal of cancer cells by immune cells (16).
CRP is considered a clinically significant biomarker based on current evidence and a static variable in predicting prognosis. However, CRP kinetics has been considered a variable to measure prognosis; therefore, its potential as a dynamic variable has also been reported. Saito et al. measured CRP levels before and after second-line chemotherapy and not before surgery (35). The prognosis was evaluated based on the kinetics of CRP. In the umbilical evaluation, patients were divided into groups based on CRP levels greater or lesser than 5 mg/L. Patients with preoperative CRP levels of ≥5 mg/L were categorized as the non-normalized group, and those with levels ≤5 mg/L were considered the normalized group. The study reported that patients in the non-normalized group demonstrated poor prognosis before and after surgery (HR 2.21, P = 0.001). Tanaka et al. also compared the prognosis of individuals with CRP levels ≤5, 5.1-20, and ≥20 mg/L. Patients with CRP levels >20 mg/L had poor CSS and recurrence-free survival (RFS) compared to those with values ≤5 mg/L (HR 1.74, 1.47, P = 0.0009 and 0.007, respectively) (31).
Several studies have reported on the prognostic role of NLR in MIBC and metastatic BC ( Table 2) (24,41,(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60). Furthermore, several studies have reported on the role of prognostic factors in survival outcomes of MIBC and metastatic UC (24, 41, 47, 48, 50, 52-56, 59, 60), while other studies have suggested that the postoperative stages or disease severity can be predicted ( Table 3) (41,48,49,58,(69)(70)(71)(72)(73). The majority of the studies reported a positive role of a high NLR on the prediction of worse OS and CSS rates. Furthermore, elevated NLR has been reported as an independent predictor of recurrence in several studies (32,41,50,52,55), with some reporting higher NLR values in patients with MIBC compared to those with NMIBC (69,70). Other studies have reported on considering the NLR in predicting disease severity, such as extravesical involvement, upstaging, or LN involvement (48,49,55). Furthermore, some studies have considered the NLR to predict the pathologic complete response after chemotherapy or surgery (58,72,73). Seah et al. analyzed NLR kinetics before, during, and after NAC and reported differences in the patterns between the CR and non-responder groups (72). Although the role of the preoperative evaluation of NLR has been commonly discussed, some studies have assessed the prognostic value of changes in the ratio through repeated measurements over time (56). Kang et al. reported that postoperative NLR increases were associated with adverse pathological outcomes and were predictors of worse OS and CSS (51). Patients with consistently elevated NLR before and after surgery had worse OS and CSS compared to other patients (51). Yoshida et al. predicted patient prognosis by comparing the NLR before and after surgery (24). Patients  (59). One study analyzed the differences in the NLR over a period of 1-5 years after surgery and reported significant results of 1-year OS (P = 0.018) and 1-year CSS (P = 0.001) rates; however, there was no difference in the rates due to differences in the NLR from the 2nd year onwards (56). The majority of the studies have reported that the NLR before and after surgery or chemotherapy can be used to predict survival outcomes, pathological findings, and disease progression. Thus, measurement of the NLR before and after treatment is a reliable   (66). The study reported that a high preoperative NLR was associated with an increased risk of recurrence of BC (HR 2.49, P = 0.015). The majority of the studies have reported  a link between the CSS and RFS (101, 103, 105, 106). The European Association of Urology proposes the NLR as a prognostic factor for CSS in patients with UTUC (4). However, the evidence supporting prognostic role of NLR in UTUC remains low, and currently there are no guidelines of risk stratification (4). Studies that evaluated the prognostic value of the NLR before chemotherapy for advanced or metastatic disease, wherein surgery was inappropriate, mainly reported on patients with BC and UTUC (Table 4) (55,(74)(75)(76)(77), with a cutoff value of 3. Interestingly, one study evaluated the prognostic value of NLR kinetics before and after chemotherapy. A high NLR before chemotherapy helped predict poor survival outcomes (76).

GLASGOW PROGNOSTIC SCORE AND MODIFIED GLASGOW PROGNOSTIC SCORE
The GPS and mGPS are a combination of CRP and albumin scores, representing methods designed to predict the prognosis of cancer patients. The GPS system is an indicator of the nutritional status of an individual based on systemic inflammation. McMillan et al. first introduced GPS for predicting the prognosis of patients with non-small cell lung cancer (101). Since then, GPS has proved to be useful in predicting the prognosis of patients with a variety of cancers, including colorectal, esophageal, lung, gastric, pancreatic, and liver cancers (101). Recently, few studies recorded the aforementioned scores before chemotherapy and surgery in patients with UC (

PLATELET-TO-LYMPHOCYTE RATIO
Several studies have reported on the prognostic value of the preoperative assessment of the PLR (

DISCUSSION
Since hematologic tests in cancer patients are basic and frequently repeated, SIR biomarkers using them can be easily obtained in cancer patients and used as economic and objective parameters. In the UC, in the system for predicting the existing prognosis or in nomogram and risk stratification studies, hematologic factors predicting pathological prognoses such as the number of tumors, tumor diameter, tumor grade, T stage, CIS, and LIV rather than biomarkers I mainly used them (12,17,26,47,95). However, in the case of clinical staging, the upstaging rate in pathological results after RC reaches 50%, and its accuracy is still low (12). Therefore, there is a need for other biomarkers to predict the prognosis of patients before treatment and to stratify risk, and for this purpose, SIR-related hematologic biomarkers can be a potential and effective factor. In the UC, the SIR biomarker is known to play an essential role in the progression and various oncologic outcomes, even though the inflammatory process develops cancer. In particular, CRP and NLR seem to be particularly useful for these oncologic outcomes and as predictors. And Albumin, AGP GPS, mGPS, PLR, etc. are potential factors, but they still lack data. The standard treatment for NMIBC is TURBT (2). However, due to frequent relapses and progression to MIBC after TURBT, regular examinations, and long-term follow-up are required (2). This repeated and long-term follow-up is putting a high economic burden on the patient (2). In addition, cystoscopy, the most representative test method, is an invasive test that causes significant pain and discomfort to the patient. Based on previous study results, patients with high CRP before surgery in NMIBC have a significant correlation with adverse outcomes in treatment outcomes and survival (18,19). NLR had a high rate of pathologic upstaging in patients with increased NLR before TURBT (37)(38)(39)(40)(41)(42)(43)(44)(45), and the risk of progression to MIBC was also high (69,70). SIR biomarkers can also be of great help in predicting the prognosis of NMIBC patients and determining the duration or method of follow-up and re-TURB. For MIBC, the standard treatment is RC. There are also various supplementary treatments such as chemotherapy, RT, and immunotherapy. In MIBC (3), patients with high CRP before surgery have a significant correlation with adverse outcomes in treatment outcomes and survival. And NLR was relatively low in complete response and pathologic T0 in patients with high NLR before RC or before NAC (47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60). And increased NLR levels during 1-3 months post RC were associated with adverse survival outcomes (12). The SIR biomarker may be helpful in MIBC patients considering the sequence and timing of treatment such as immediate RC and NAC after prognosis. And the patterns of change in NLRs before and after surgery can also provide useful information for determining additional target groups, such as adjuvant chemotherapy, radiation therapy, and immunotherapy. In addition to the systemic inflammatory response, CRP is a biomarker that predicts the outcome of IL-2 or IFN-α immunotherapy and has been considered in the evaluation of patients with renal cancer (104). Patients with normal CRP have been reported to demonstrate good tolerance and adherence to immunotherapy (104). The scope of immunotherapy is expanding in patients with UC, and CRP could be considered a factor in predicting the prognosis and compliance to treatment.
The limitations of SIR biomarker's research at UC are: First, there is no objective and clear cut off value. Second, unlike pathological prognostic factors, SIR biomarkers may be affected by other inflammatory diseases or physical conditions other than the patient's cancer. And third, due to the nature of the research, most studies are retrospective and lack of large-scale prospective research results.

CONCLUSION
In this review, we discussed the applicability of CRP, AGR, albumin, GPS, mGPS, NLR, and PLR as SIRs in patients with UC. These SIRs have proven to be useful during preoperative evaluations in the treatment and risk assessment of patients with UC. However, there is a need to develop uniform classification criteria with a consensus regarding the use of these SIRs in clinical settings. We believe that large prospective studies are needed on this subject based on observations of this retrospective review.