Testicular tumor is quiet a rare disease, 90-95% of testicular tumors are testicular germ cell tumors (TGCT) (1). The main methods for diagnosis of testicular tumors are physical examination, radiography, ultrasound and biochemical tumors markers including alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG) and lactate dehydrogenase (LDH) (2). However, these markers are not very specific, AFP and HCG are increased in only 40-60% patients with TGCT, while HCG elevation can be detected in only 30% of seminoma (3), therefore, false positive and negative result are often observed by those examinations, so other simple, inexpensive, easily applicable and more accurate markers are needed in the clinical approach.

Inflammatory markers are with low cost and can be easily available from the routine hemorrhagic data, and the relationship between inflammation and various tumor is confirmed by several studies, it may play an essential role in regulating the progression of the cancer by stimulating or suppressing tumor cells (4, 5). When regrading to urological tumors, several studies demonstrated that inflammatory factors may be associated with progression and prognostic of renal cancer, bladder cancer and prostate cancer (6). Especially for neutrophil to lymphocyte (NLR), as one of the most important inflammatory markers, it has been reported to be closely related with recurrence and prognosis of kidney and bladder cancer (6, 7). However, few studies have detected the association of inflammation with testicular tumor, and among the published papers the conclusions are still controversial, further studies are needed to detect whether there is an association between inflammation and testicular tumors, and whether inflammatory parameters can be used as predicting markers for testicular TGCT. The aim of this study is to clarify whether complete blood count (CBC) based inflammatory markers including lymphocyte ratio (LR), platelet/lymphocyte ratio (PLR), lymphocyte/monocyte ratio (LMR), systemic immune-inflammation index (SII), lymphocyte ratio (LR), neutrophil ratio (NR), mean platelet volume (MPV) and red cell distribution width (RDW) could be used as serum markers for predicting TGCT, if so, great clinical values will be provided in predicting testis TGCT for patients with testis masses before surgery.

The relationship between inflammation and cancer has long been known, a range patterns of cellular immune response to different histological tumors types are reported. In 1863, Virchow hypothesized that chronic inflammation could irritate cell proliferation along with the inflammation leading to cancer occurs (19). The immunocompetent cells that infiltrate tumors are mostly T-lymphocytes and microphages, with a few B-lymphocytes and NK-cells (20). Neutrophils mediate inflammation through various biochemical mechanisms such as platelet aggravating factors and release of arachidonic acid metabolites, and lymphopenia is associated with cortisol induced stress response (21). Other systemic inflammatory markers including C-reactive protein, leukocyte and cytokines were reported to be independent prognostic factors for patients with malignant (22). In recently, in addition to those inflammatory markers some papers reported that several CBC based parameters including NLR, PLR and SII are associated with the formation and progression of several kinds of malignant tumor (22, 23). Inflammation caused neutrophil response increasing and lymphocyte suppression led to the high NLR supported the development of malignant tumor by inhibiting the antitumor immune response (24). In preclinical experiment, data shown that increased neutrophils could stimulate tumor growth through different mechanisms (25). PLR has also been proved to be effective markers of system inflammation, and PLR combined with NLR are thought to be reliable independent prognostic factors in patients with malignancy (26). SII is a new developed joined tool combined with neutrophils, lymphocytes and platelet, recently it is used to assess the information of progression and prognostic in patients with malignant tumor (8, 27). Compared with NLR and PLR, SII is thought to be a more powerful tool combining three independent prognostic factors in cancer (28). And high SII has been demonstrated to be associated with tumor progression and poor outcomes in various kinds of cancer (29).

Meanwhile, the presence and consequences of cancer-related systemic inflammatory response have been investigated in various urologic cancers. Studies assessed that inflammation might be associated with development of urinary system malignancies such as bladder cancer, renal cancer and prostate cancer (30). A meta-analysis evaluating the relationship between NLR and prognostic found that high NLR was associated with poor prognosis in urological tumors beyond testis tumor (31). Bell et al. investigated the nature of inflammatory cell infiltrated in 10 testicular seminomas, found all of the 10 tumors contained a slight to marked inflammatory cell infiltrate at the periphery of the tumor, indicated that 2 types of immune-inflammatory reactions may play crucial role in the testicular seminomas (32), as sensitive markers reflecting inflammatory-immune status of the body NLR and SII may be affected, but the number of studies on the association of inflammation with testicular tumors is really small, most evaluations were performed using NLR and PLR, and the results are controversial. A study comparing patients with early-stage testicular tumors with healthy men confirmed that NLR above 2.7 should be considered the diagnosis of tumor (33). Another study demonstrated pre-operative CBC based parameters including NRL, RDW, MPV, LR and NR are all associated with progression and prognostic in patients with testicular tumors (34). Some other literatures demonstrated that TGCT were associated with prominent lymphocytic infiltrate (35, 36). In contrast, in some other studies, the conclusion was different. In a study assessing the association between inflammation factors and progression and prognostic in patients with TGCT, no correlation was found between NLR and stage, cancer specific survival (CSS) time and progression free survival (PFS) time (37). As a powerful tool in predicting various cancers, few studies reported the relationship between SII and testicular tumors. Only in recently years, a retrospective study demonstrated that high SII (≥1003) was associated with poor outcomes in patients with TGCT (23). Therefore, it is still controversial to define whether inflammation factors are associated with occurrence and progression of testicular tumors and which parameters can be considered as the most effective predictors for diagnosis of testicular tumors and disease progression, and further studies are needed detecting the role of SII in TGCT.

The most usually used methods for diagnosis of testicular germ cell tumors included testicular ultrasound, serum AFP and HCG, but false positive and negative result are often observed by these examinations, it is difficult for ultrasound to separate germ cell tumors from other testicular tumors, and the level of AFP and HCG are easily influenced by other diseases, eg: hepatitis, hepatoma tumors, ovarian tumors, stomach tumors (38, 39), so other simple, inexpensive and easily applicable markers are needed in the clinical approach. New miR based serum biomarkers including miRNA-367-3p, 371a-3p, 372-3p and 373-3p have shown great potential with high sensitivity and specificity for predicting TGCT, compared with miR cluster, the specific of SII and NLR are comparable, but the sensitivity is much lower (12–18, 40), inflammatory markers in this study seemed have no too much advantage compared with miR cluster, but the extraction of miR from the fluid needs specific equipment and professional researchers, not all the centers could perform that, for SII and NLR, they could be calculated based on CBC, easily available and much cheaper compared with extraction of miR cluster. Therefore, SII and NLR could be considered as valuable markers, and they were more likely becoming the common clinical method for predicting TGCT compared with miR cluster. In this study, we sought to detect the potential association between pre-operative CBC based blood count parameters including NLR, PLR, LMR, SII, LR, NR, MPV and RDW with TGCT. After analyzing the data, the major findings of our study are: 1) NLR, SII and RDW are significantly higher in patients with TGCT compared to tumor-free healthy patients; 2) NLR and SII all could be used as effective bio-markers for the prediction of TGCT, while SII seemed to be a more favorable choice due it got the largest AUC area of 0.725 compared with NLR of 0.704; 3) More than half of the cases in this study are with stage II or III, due to the small sample size, we did not compare the data of tumor group with control group according to the pathological stage, separately. However, after grouping the patients by cut-off value of SII or NLR, we found that NLR above 3.38 or SII above 881.24 are associated with higher pathological stage, the volume of the disease may affect the inflammatory parameters. The outcome of NLR including its role in predicting testicular tumor and cut-off value are mostly conformal with data reported by literatures (33, 41). While few studies have detected the correlation between SII and TGCT, in our study, for the first time in the literature, the role of SII in predicting TGCT was analyzed and the results indicated that SII had diagnostic value in detection TGCT, which was really help for patients with testis mass who refused performing surgery or biopsy, and the cut-of value of SII was similar with that reported by Michal et al. (23).However, according to our study, inflammatory markers seemed not able to distinguish the pathological types of the TGCT, for there were no significant differences of CBC based parameters between sTGCT and nsTGCT.

Meanwhile, our study has some limitations. As a retrospective study, the sample size is relatively small due to the low incidence of testicular tumor, only 58 cases with GTCs are included. And our study lacks the following-up data while most of the patients included are seminoma making it very difficult to measure the factors associated with prognostic. And one single time point was used for measuring the biomarkers leading to the inaccurate of the data collected, it can be strengthened by collecting blood samples at different pre-operative sets. Extended sample size and following-up data were needed in further research.

In conclusion, this study demonstrated that NLR and SII were all effective markers for urologists predicting the occurrence of TGCT, as they showed superior performance in detecting TGCT; in addition, SII is a more powerful tool among these 2 inflammatory factors for predicting TGCT. Extended sample size and prospective studies are needed.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Institutional Review Board of Peking University Cancer Hospital & Institution in April 2020 (protocol code 2018KT27). Written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements.

DP and WS designed the study. SW, XY, and ZY made the same contribution in this study. SW, XY, ZY, YJ, YC, JM and YY performed the study and analyzed the data. PD, SW, XY and ZY wrote the manuscript draft and revised the manuscript. All authors contributed to the article and approved the submitted version.

Beijing Municipal Science & Technology Commission. No. Z181107001718142. Science Foundation of Peking University Cancer Hospital. No.2021-7; Wu Jie Ping Medical Foundation. No. 320.6750.2020-19-2.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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