The potential value of red blood cell distribution width in patients with invasive hydatidiform mole

Background Red blood cell distribution width (RDW) has attracted increasing attention in cancer. The aim of this study was to assess the changes of RDW in patients with invasive hydatidiform mole and analyze the relationship between RDW and invasive hydatidiform mole. Methods A retrospective analysis was performed on 102 patients diagnosed as invasive hydatidiform mole in the First Affiliated Hospital of Guangxi Medical University from January 2009 to March 2018. A total of 120 healthy subjects were used as a control group. The Mann‐Whitney U test was used for comparison between the invasive hydatidiform mole and control groups. Comparison of RDW with other blood parameters was performed using Spearman's. The area under the ROC curve (AUC) and 95% confidence interval (95% CI) were also determined. Results The RDW, platelet‐lymphocyte ratio (PLR), neutrophil‐lymphocyte ratio (NLR), and absolute lymphocyte count were significantly elevated in the invasive hydatidiform mole group compared with control group. The hemoglobin (Hb) concentration, mean red blood cell volume (MCV) and platelet count (PLT) were significantly lower in invasive hydatidiform mole group than control group. Grade III and above invasive hydatidiform mole patients had higher levels of RDW than grade I and II patients. Correlation analysis showed that RDW was negatively correlated with Hb, MCV, NLR, and neutrophil count, but positively correlated with PDW and different stages of invasive hydatidiform mole. The ROC curve showed that the AUC of the RDW was 0.660 (95% CI 0.581‐0.740; P < 0.01). Conclusion This study reveals the potential value of RDW in invasive hydatidiform mole.

30 years due to economic and dietary improvements and a decline in overall birth rate. However, invasive hydatidiform mole has malignant tumor behavior and can undergo extensive metastasis. 3 If left untreated it can be transformed into choriocarcinoma with poor prognosis, which can lead to significant morbidity and mortality. 4 Therefore, early diagnosis of invasive hydatidiform mole is critical for rapid and accurate treatment management.
Red blood cell distribution width (RDW) is a parameter for routine examination of whole blood counts, which is a quantitative measure of changes in circulating red blood cell size. 5 In addition to routine assessments in the differential diagnosis of anemia, studies have shown that there is a hierarchical independent relationship between high RDW levels and the occurrence of cervical, ovarian, and endometrial cancer. [6][7][8] Similar to RDW, mean platelet volume, platelet-to-lymphocyte ratio, and neutrophil-to-lymphocyte ratio have also been reported as inflammatory markers in patients with inflammatory diseases, while they have prognostic significance for cancer. 9,10 It is currently believed that cancer is often the net result of chronic inflammation. Malignant tumors can also lead to malnutrition with chronic inflammation. 11 In general, biomarkers (such as age, stage, and performance status) are used to stratify patients and guide treatment decisions. Since invasive hydatidiform mole does not have specific tumor markers, it is necessary to find markers for early detection and monitoring of high-risk patients. At present, there are no data on the correlation between invasive hydatidiform mole and RDW. In this study, we intend to investigate the clinical significance of RDW in invasive hydatidiform mole.

| Patients
The study was approved by the Ethics Committee of the First Affiliated Hospital of Guangxi Medical University. Patients with a history of diabetes, cardiovascular disease, hepatitis B, chronic obstructive pulmonary disease, kidney disease, blood disease, or any medication or treatment that may interfere with hematology were excluded. A total of 102 inpatients diagnosed with invasive hydatidiform mole were enrolled between January 2009 and March 2018.
A total of 120 healthy subjects were used as a control group. All patients with invasive hydatidiform mole were histologically and graded by pathology and/or cytology: 54 were stage I and II, 48 were stage III and IV.

| Methods
A total of 2 mL venous blood sample was collected from each patient who was first diagnosed as an invasive hydatidiform mole and did not receive any treatment in the morning blood draw. All blood samples were placed in EDTA-K2 anticoagulation tubes. All measurements were analyzed using a Beckman Coulter LH 780 Hematology Analyzer (Beckman Coulter, Brea, CA) within 30 minutes after blood collection. Where white blood cell count (WBC), hemoglobin (Hb) concentration, platelet count (PLT), mean red blood cell volume (MCV), mean platelet volume (MPV), RDW, platelet distribution width (PDW), absolute neutrophil count, (N) and absolute lymphocyte count (L) were obtained directly from the blood analyzer, while neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) were obtained by dividing absolute neutrophil count or platelet count by absolute lymphocyte count, respectively. The normal range for RDW in our hospital is 11.0%-14.0%.

| Statistical analysis
Statistical analysis was performed using SPSS 20.0 software (SPSS 20.0, Chicago, IL). The normality test was performed using the Kolmogorov-Smirnov test, and the results showed that no measurement data conformed to the normal distribution. The test parameters of the non-normal distribution are expressed as median (interquartile range). The Mann-Whitney U test was used to analyze the parameters of invasive hydatidiform mole patients and control group. The association of RDW with other whole blood parameters was analyzed using Spearman's test in the invasive hydatidiform mole group. The area under the ROC curve (AUC) and 95% confidence interval (95% CI) were also determined. P < 0.05 was considered to be statistically significant.

| RE SULTS
According to exclusion criteria, a total of 102 patients (mean age 30.00 years; range 23.75-37.00 years) with invasive hydatidiform mole were included in this study. A total of 120 normal people Comparison of laboratory hematology parameters between groups is shown in Table 1. The results showed that the level of RDW, absolute lymphocyte count, NLR, and PLR was significantly higher in the invasive hydatidiform mole group compared with the control group (P < 0.05). The Hb concentration, MCV, and PLT were significantly lower in the invasive hydatidiform mole than the control group (P < 0.05).However, the age, WBC, MPV, PDW, and absolute neutrophil count between invasive hydatidiform mole and control groups were not significantly different (P > 0.05).
After pathological examination, 102 patients were diagnosed as invasive hydatidiform mole, of which 54 were stage I and stage II, and 48 cases were stage III and stage IV. The results showed that patients with grade III and IV invasive hydatidiform mole had higher RDW levels than patients with stage I and II [0.15(0.14-0.16) vs 0.13(0.13-0.15); P < 0.01] ( Table 2). The ROC curve showed that the AUC of the RDW was 0.660 (95% CI 0.581-0.740; P < 0.01).
The association between RDW and other systemic blood inflammatory parameters was assessed using a correlation analysis.

| DISCUSS IONS
RDW is a parameter that reflects the heterogeneity of peripheral red blood cell volume and is considered to be a systemic inflammatory marker of in many chronic inflammation. 12 As a low-cost test, it is usually reported in the complete blood counts. 13 Elevation of RDW may occur in ineffective red blood cell formation (iron deficiency, B12 or folate deficiency, and hemoglobinopathy), microangiopathic hemolytic anemias, increased red blood cell destruction (hemolysis) or post-transfusion. 14 Although recent studies have clearly demonstrated that RDW is a reliable biomarker for cardiovascular morbidity and mortality, [24][25][26] the underlying mechanism between inflammation and elevated RDW levels remains unclear. It is currently believed that cancer is developed from chronic inflammation. 27 The mechanism of RDW elevation in patients with invasive hydatidiform mole is still under investigation, but the possible mechanisms include the following.
First, inflammatory factors can induce an increase in RDW, increase heterogeneity of peripheral red blood cell volume, and inhibit bone marrow hematopoietic function. 28 The decrease in red blood cell survival rate, impaired iron metabolism and decreased red blood cell deformability can lead to inhibition of erythropoietin response at the same time. In patients with malignant tumors, overproduction of circulating cytokines such as interleukin-6, tumor necrosis factor alpha and CRP has also been shown to play a key role in the induction of chronic inflammation. 29,30 In addition, many types of inflammatory factor receptors are detected on the surface of red blood cells, and it is speculated that red blood cells are involved in the inflammatory process. Hunziker et al 31

| CON CLUS IONS
In conclusion, this study is the first to reveal the potential predictive role of RDW in patients with invasive hydatidiform mole. This clinical study also reported for the first time a significant correlation between clinical and pathological staging of patients with invasive hydatidiform mole. It is difficult to make appropriate monitoring plans and appropriate treatment strategies in time as the patient's clinical stage changes in clinical cancer treatment. Therefore, inflammatory parameters become important as prognostic or predictive markers.
Since RDW is widely used for routinely implemented whole blood counts and is highly reproducible, this cheap and readily available parameter may serve as a new and convenient marker for understanding a patient's disease status and assessing tumor stage.

ACK N OWLED G M ENTS
We are grateful for the support of the clinical laboratory of the First Affiliated Hospital of Guangxi Medical University.

AUTH O R CO NTR I B UTI O N S
The design and writing of this paper were completed by Lingling Zhang. Youjun Xie contributed to the collection of clinical data and analytical data. The manuscript was reviewed by Lingling Zhan.