Patients
The current study was conducted on a cohort of 176 patients suffering from type 1 EC, treated in the Gynecology and Obstetrics Department of the Independent Public Healthcare Facility Regional Complex Jan Sniadecki Hospital in Bialystok, Poland in 2006-2012. The study protocol was approved by the Bioethics Committee at the Medical University of Bialystok, Poland (R-I-003/177/2004). Enrolled patients were informed of the study's purpose and gave their consent for the study. All patients were treated surgically in accordance with FIGO criteria. The standard blood tests, chest radiographs, and abdominal ultrasound tests including pelvis were performed. In several cases, CT or MRI was performed too. Performed procedures included a hysterectomy with bilateral salpingo-oophorectomy (n=83), hysterectomy with bilateral salpingo-oophorectomy, and bilateral pelvic/paraaortic lymphadenectomy (n=93). Patients included in this study had not been given any preoperative treatment. Histopathological examination was performed according to the guidelines and classification of the WHO. The surgical specimens were analyzed by medical pathologists. In order to confirm the clinical FIGO stage, the depth of myometrial invasion, histopathological tumor type and grade, and the absence or presence of LVSI via light microscopy examination all tissue samples were gathered and H&E.
Collection and storage of samples
Blood samples were collected into a serum separator tube (Vacutainer, Becton-Dickinson, USA) and allowed blood to clot at room temperature for 30 minutes. All samples were centrifuged at 3000 g for 10 minutes then collected; the supernatant was stored at -80°C until examination.
Immunoassays
We used commercially available Quantikine human ELISA kits (R&D systems, Minneapolis, MN, USA) for adiponectin, high sensitivity-C-reactive protein (CRP), VEGF-A, Ang-2 and IGF-1 and human ELISA kit (Millipore, Billerica, MA, USA) for insulin and C-peptide to measure protein levels in the patients’ serum samples. All ELISAs were carried out according to manufacturers’ instructions and samples were assayed in duplicate according to proper control standards. Human Total Adiponectin/Acrp30 Quantikine ELISA Kit DRP300 (sensitivity: 0.891 ng/ml, assay range: 3.9-250 ng/ml) Human C-Reactive Protein/CRP Quantikine ELISA Kit DCRP00 (sensitivity: 0.022 ng/ml, assay range: 0.8-50 ng/ml Human VEGF Quantikine ELISA Kit DVE00 (sensitivity: 9 pg/ml, assay range: 31.3-2,000 pg/ml) Human Angiopoietin-2 Quantikine ELISA Kit DANG20 (sensitivity: 21.3 pg/ml, assay range: 46.9-3,000 pg/ml) Human IGF-I Quantikine ELISA Kit DG100 (sensitivity: 0.056 ng/ml, assay range: 0.1-6 ng/mL Human Insulin ELISA EZHI-14K Millipore (sensitivity: the lowest level of insulin that can be detected by this assay is 0.85 µU/mL when using a 20 μl sample size, specificity: 100%). Human C-Peptide ELISA EZHCP-20K Millipore (sensitivity: the lowest level of Human C-Peptide that can be detected by this assay is 0.05 ng/ml, specificity: 100%). Personnel running the assays was not informed of patients’ clinical status, and the results were disclosed to the surgeons only after recording patients’ disease status. The test precision for markers was performed in accordance with the protocol guidelines of the Clinical and Laboratory Standards Institute (CLSI) [22].
Data collection
Demographic and clinical data, as well as the pathology report for every patient, have been prospectively stored in the hospital database. Baseline height, weight, and BMI have been acquired from medical records along with the follow-up information. The BMI was established in accordance with the following: <19.9 kg/m2 - underweight; 20-24.9 kg/m2 - normal; 25-29.9 kg/m2 - overweight; ≥30 kg/m2 being obese. The BMI decreased with age >60 years. Only 1.1% of patients appeared to be underweight, 8.5% were normal, 52.3% - overweight and 38.1% were obese, among them 5.4% morbidly obese. 21 patients (11.9%) were diagnosed with diabetes mellitus type 2. All follow-ups were concluded before 30 September 2018.
Statistical analysis
Statistical analysis was performed in Statistica software package 13.3 PL (StatSoft, Inc. StatSoft Poland Ltd.). Frequency and descriptive statistics were applied to characterize the cohort. Independent-sample T-tests to compare serum markers levels in patients with or without LVSI, myometrial invasion, FIGO stage, grade, and age were used (or Mann-Whitney-U test when appropriate). Correlation between the selected markers of angiogenesis, inflammation, insulin resistance and obesity was assessed using Pearson’s correlation analysis. Biomarkers that showed significant correlation were analyzed by linear regression to determine the working relationships between the biomarkers. We successively conducted both Kaplan-Meier and Cox regression analyses so that we could analyze the overall survival of the patient. We applied medians in order to divide continuous data into groups for Kaplan-Meier analysis, with standard cut off points for BMI. For the continuous variables, hazard ratios were estimated using the following units: 100 units of VEGF-A, 1000 units of Ang-2, 1 unit of CRP, insulin, C-peptide, and BMI, 10 units of IGF-1 and per decade of age. Predictors were entered either on their own or jointly; stepwise procedures were not used. The Cox-proportional hazard model was used to assess the prognostic value of serums VEGF-A, Ang-2, Adiponectin, Insulin, C-peptide, CRP, IGF-1 and BMI as log-transformed continuous factors in univariate and Ang-2 and CRP in multivariate analyses. The base model consisted of traditional prognostic factors such as FIGO stage, age, tumor grade, myometrial invasion, and LVSI. Levels of VEGF-A, Ang-2, Adiponectin, Insulin, C-peptide, CRP, IGF-1 and BMI were entered separately in a second block. Points estimated were reported as hazard ratios (HRs) and 95% confidence intervals (CIs). P<0.05 was found to be statistically significant.