Patients
In this retrospective study, 180 patients with liver cancer underwent surgical resection in the Liver Center of the First Affiliated Hospital of Chongqing Medical University from January, 2013 to June, 2017. HCC was diagnosed by imaging or histological examination in accordance with AASLD or EASL guidelines, and patients with HCC who underwent surgical treatment were included.
Inclusion criteria: (1) A preoperative child-pugh score of A or B, with liver reserve function as well as residual liver volume that meet surgical requirements; (2) No tumor rupture or various primary/secondary infections; (3) The resection marginconfirmed free of cancer cells by postoperative pathological examination; (4) Hepatocellular carcinoma confirmed by Postoperative pathological examination and immunohistochemistry ; (5) No invasion of large vessels or distant metastasis.
Exclusion criteria: (1)Tumor recurred, during TACE treatment, within 2 months after the operation; (2) Prior to the first diagnosis of tumor recurrence, patients received adjuvant therapy other than TACE; (3) Lost to follow-up within 1 year after surgery; (4)Patients was diagnosed with extraheptic diseases that cause abnormal numbers of blood cells such as blood or immune system diseases. Clinical data(age, sex, hepatitis B, cirrhosis, preoperative blood routine, liver function, and AFP, etc.) and tumor data (tumor size, number of tumors, degree of differentiation, MVI grade, etc.) of enrolled patients were collected, and the tumor data were issued by the Department of Clinicopathology, Molecular Medical Testing Center, Chongqing Medical University.
Treatment Procedures
Patients who met inclusion criteria were given segmental hepatectomy, hemihepatectomy or tumor resection according to the size, location and distribution of tumors. One month after the surgery, TACE therapy was applied to subjects with an MVI grade higher than or equal to M1 or with moderately or poorly differentiated carcinoma, as per their tolerance11. Seldinger technique was used to puncture and catheterize femoral artery. Then transcatheter arterial chemoembolization was performed with lipiodil and chemotherapy drugs (oxaliplatin, irinotecan, epirubicin or pirubicin) after the assessment of dose based on body surface area and liver function. Before treatment, all patients signed the informed consent of relevant treatment and voluntarily chose TACE treatment.
Follow-up and outcome indicators
The outpatient follow-up assessment included liver and kidney function tests, quantitative HBV-DNA, tumor markers, abdominal color Doppler ultrasound or enhanced computed tomography of the abdomen and chest. And the follow-up was set to end at June 20, 2020, with a median of 47 months (95%CI: 43.2–50.7). Overall Survival (OS) was defifined as the time interval between initial TACE and all-cause death.
Predictors and sample size
Relevant studies have shown that factors including tumor number, maximum diameter of tumors, Edmondson-Steiner grade8, MVI grade12, Ki6713, age, gender, hepatitis B surface antigen5, cirrhosis10, alpha-fetoprotein, albumin-bilirubin grade14, Child-pugh grade, BMI15, NLR16, PLR17 all have an effect on the prognosis of adjuvant therapy after hepatectomy, we related these factors as predictors of prognosis in this study.
The number and maximum diameter of tumors were measured using enhanced CT or MRI before surgical resection. Edmondson-steiner grade, MVI grade, Ki67 were evaluated by the Clinicopathology Department of Molecular Medical Testing Center of Chongqing Medical University, according to corresponding criteria 18, 19after surgical resection. Edmondson-steiner grade (≥3 or < 3), MVI grade (M0 or > M0), and Ki67 (≥20% or < 20%) along with the number of tumor (≥2 or < 2), and the maximum tumor diameter (≥5cm or< 5cm) were all considered as categorical variables.
Preoperative data inclueded age, sex, hepatitis B surface antigen, cirrhosis, alpha-fetoprotein, albumin-bilirubin grade, Child-pugh grade, BMI, NLR, PLR. Among them, age (≥55 years or < 55 years), hepatitis B surface antigen (Measured by blood drawing), cirrhosis(Diagnosis was made according to European guidelines for cirrhosis20), alpha-fetoprotein (≥200mg/L or < 200mg/L), albumin-bilirubin grade (grade 1 or grade 2) and Child-pugh grade (A or B)" were categorical variables. And BMI, NLR and PLR were continuous variables.
Three predictive factors ((MVI (P=0.00643), tumor number (P=0.03056) and BMI (P=0.08092)) were further screened by least absolute shrinkage and selection sperator(Lasso) analysis for model development. Only complete data were analyzed in this study. The minimum sample size determined by EPV(Event per Variable) criterion21 is 30, so this thesis meets statistical requirements of sampling and has sufficient accuracy.
Model Derivation and Validation
NLR normally distributed after logarithmic transformation, and the rest continuous variables were basically of normal distribution as well. The converted values of non-normal distribution continuous variables were recorded. Continuous variables identified as predictors of survival were analyzed using spline functions to assess their correlation with outcome variables and test their nonlinearity.
Cox proportional risk model was used to screen variables, establish the model, and calculate the predicted values. Area under the curve(AUC) and Brier Score were calculated to evaluate the model. Then model deviration was performed, including linear relationship, strong influence point, multicollinearity, and proportional risk hypothesis. Harrell's C statistics and Brier score were obtained by enhanced bootstrap for internal validation to evaluate the differentiation and calibration of the model. In this study, Harrell's C statistic22 was equival to the overall C statistic of the model. On account of the lack of relevant prognostic models, the final model was compared with both ALBI and child-pugh grade by C statistic and likelihood ratio test. Corresponding P value < 0.05 indicates that the difference is statistically significant. All analyses are performed using R version 4.1.2. All authors have full access to the study data and have reviewed and approved this manuscript.
Ethics
This retrospective study, in compliance with the 1975 version of the Declaration of Helsinki, has been approved by the Ethics Committee of the First Affiliated Hospital of Chongqing Medical University, the approval number being 2019021.