Background
Renal cancer accounts for 2% to 3% of all cancers, and the rate of renal cell carcinoma (RCC) has increased by 1.6% per year for the past 10 years [
1]. Approximately 90% of renal cancer is RCC, and surgery is the only curative treatment. About 20% of RCC patients have advanced stage disease, and for those with localized RCC, nearly 30% show recurrence after tumor resection [
2,
3]. Therefore, we need better prognostic models to improve prognosis.
The TNM stage, reflecting tumor invasion, lymph node metastasis and distant metastasis, is the most widely used system for predicting RCC prognosis [
2]. However, because of heterogeneous prognoses, the outcomes of some patients with the same stage of cancer may be completely different. Therefore, we need useful biomarkers to increase the prognostic accuracy in RCC.
Increasing evidence supports that inflammation and nutrition are involved in the initiation and progression of various cancers, including RCC [
4]. Hematologic parameters including albumin and hemoglobin levels and lymphocytes, neutrophils and platelets counts are easily acquired laboratory data reflecting inflammation and nutrition status and have been extensively studied. Numerous studies have reported the prognostic value of serum albumin and hemoglobin levels and lymphocyte and platelet counts for various cancers, including RCC [
5‐
8]. However, the disadvantage of these indicators is that each reflects only one respect of inflammation or nutrition. Further studies found that the combination of those factors in an index such as the prognostic nutritional index (PNI), combining albumin level and lymphocyte count, or the neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR) or platelet-to-lymphocyte ratio (PLR) could more accurately predict prognosis than a single index [
9‐
12].
A novel index combining hemoglobin and albumin levels and lymphocyte and platelet counts (HALP) has been found significantly associated with outcomes in colorectal and gastric cancer [
13,
14]. In this study, we investigated the clinical value of this index in RCC patients undergoing nephrectomy.
Discussion
In this study, we evaluated the prognostic significance of the novel index HALP combining hemoglobin and albumin levels and lymphocyte and platelet counts in RCC patients undergoing nephrectomy. HALP was closely associated with clinicopathologic features. Univariate and multivariate analyses demonstrated that HALP was an independent predictor of CSS for RCC patients undergoing nephrectomy. Furthermore, the nomogram based on HALP could predict prognosis more accurately than the TNM system.
There are several known predictive models of RCC such as TNM stage and the Stage, Size, Grading and Necrosis (SSIGN) model [
16]. Inflammatory and nutritional indicators based on hematologic parameters such as albumin and hemoglobin levels and lymphocyte, neutrophil and platelet counts were also associated with outcomes with RCC. Moreover, several indicators combined with hematologic parameters, including NLR, LMR, and PLR, were more accurate predictors [
6,
9,
10,
12]. Recently, indicators combining albumin level with LMR or NLR were found significantly associated with outcomes [
17,
18], which suggests better prediction of outcomes by combining inflammatory and nutritional indicators.
Accumulating evidence suggests the important role of the inflammatory response and nutritional status in cancer progression and metastasis. Overall, 30% of cancer patients were found with cancer-related anemia (CRA) at the time of diagnosis and CRA was associated with more advanced cancer stage [
19]. CRA is believed to be associated with chronic blood loss, iron deficiency, and vitamin B12 or folate nutritional deficiency. Meanwhile, imbalanced inflammation regulation, such as increased hepcidin and reactive oxygen species stress, in cancer patients is also responsible for CRA [
20]. Serum albumin is synthesized specially in the liver and known as a negative acute-phase protein. In addition, systemic factors such as inflammation and stress could affect serum albumin level. Therefore, decreased serum albumin level represents a malnutrition status and also a sustained systemic inflammation response. As important indicators of nutrition and inflammation, anemia and hypoalbuminemia are widely reported to be associated with worse outcomes in various cancers including RCC [
7,
8]. Morgan et al. [
21] reported that for locoregional RCC patients undergoing nephrectomy, 25% of patients have anemia and 5.1% have hypoalbuminemia. The authors also found hypoalbuminemia (< 35 g/L), unintentional preoperative weight loss ≥5% and preoperative BMI < 18.5 kg/m2 as reflecting nutritional deficiency (ND) and that anemia and ND were independent predictors of overall mortality and disease-specific mortality. Preoperative hypoalbuminemia and anemia were also found to predict transfusion during radical nephrectomy for RCC [
5]. We observed 3.9% hypoalbuminemia and 19.6% anemia in our patients, which is consistent with previous study. On univariate analysis, both anemia and hypoalbuminemia were associated with worse survival.
Cancer-related inflammation is considered the seventh hallmark of cancer, playing a conflicting role in tumor initiation and progression in that both tumor-antagonizing and -promoting leukocytes can be found [
22]. Elevated neutrophil count is associated with cytokine secretion and contributes to tumor angiogenesis, promotion and metastasis. CD4+ and CD8+ T lymphocytes can enhance cancer immune-surveillance to inhibit tumour cell proliferation, invasion and metastasis [
23]. Increased neutrophil count and decreased lymphocyte count might be responsible for a weak and insufficient immune response to tumors and strongly associated with a poor survival in advanced cancer [
24,
25].
Recent data implied that the activation of platelets is crucial for cancer progression by promoting angiogenesis, extracellular matrix degradation, and release of growth factors, which are essential components of tumor growth and metastatic [
26]. In addition, platelets adhering to tumor cells could secrete vascular endothelial growth factor(VEGF), which induces microvessel permeability, promotes extravasation of cancer cells, and induces neoangiogenesis [
27]. Platelet count was found a significant predictor of RCC-specific mortality [
28]. Recently, tumor-educated blood platelets (TEPs) were implicated as central players in the systemic and local responses to tumor growth. As well, the RNA profile in TEPs could provide a valuable platform for liquid biopsy [
29].
Systemic inflammation markers including NLR, LMR, and PLR have been found associated with survival in many solid tumors including RCC [
6,
10,
30,
31]. Among those indicators, the finding of elevated NLR and PLR indicated increased neutrophil and platelet count and decreased lymphocyte count associated with worse outcomes. In our study, elevated NLR and PLR were associated with worse CSS on univariate analysis. However, on multivariate analyses, HALP rather than NLR and PLR remained an independent prognostic factor.
We used nomogram of independent prognostic factors found on multivariate analyses including HALP and evaluated their accuracy by calibration curves. The predictive accuracy was better with HALP than the TNM system. TNM stage may be an important factor in RCC, but other factors such as HALP could be included and improve the prediction of outcomes.
The major limitations of the present study are its retrospective nature and the single-center design. Additional large and prospective studies are needed to confirm these findings.