Clinical characteristics of patients
A total of 344 HCC patients were included in this study, among whom 279 cases were males and 65 cases were females, accounting for 81.10% and 18.90% respectively. Details of patients’ information were shown in table 1. The patients were divided into two groups according to their age, namely the elderly group with age ≥70 years old and the young group with age < 70 years old. 258 (75%) patients had a history of hepatitis B, only 86 (25%) cases did not. Most patients had no history of hypertension or diabetes (76.74% and 88.08%). Nearly half of the patients (45.93%) had a BMI more than 23. Moreover, the patients who had liver cirrhosis were 256 (74.42%), 88 patients without liver cirrhosis, nevertheless, most of them had abnormal liver function, such as hepatitis and fatty liver. 44 (12.79%) cases had ascites, unfortunately, two of them had bloody ascites. The TNM stage of I-II and III-IV were 300 (87.21%) cases and 44 (12.79%) cases. The median of NLR and PLR was 2.19 (inter-quartile range: 1.64-3.31) and 97.67 (72.10-138.17), respectively. The median follow-up time for this study was 52.00 (10.00-78.75) months. During the follow-up period, the 1-year, 3-year and 5-year DFS of the patients were 73.26%, 59.30% and 44.48%, respectively.
Correlation between different age groups and clinicopathological characteristics of patients
The results of the correlation between clinical and pathological indicators in the elderly group and the young group were shown in Table 2. Patients without hypertension and diabetes appeared to be less common in elderly patients than in the young group (45.65% vs. 81.54% and 80.43% vs. 89.26%). As for hematological index, the age was significantly connected with HbsAg, AST, ALB, PLR (P<0.05). However, there were no statistical differences between the two groups with regard to smoking, alchohol intake, BMI, tumor number, tumor diameter, differentiation degree, TNM stage, AFP, TBIL, TC, ALT, GGT and NLR.
The prognostic factors for DFS
The results of univariate regression analysis were expressed in Table 3, and Table 4 showed the multivariate analysis of DFS which included the significant factors obtained from Table 3. Multivariable Cox regression analysis revealed that age, history of hepatitis B and TNM stage were independent factors for predicting disease-free survival rate of HHCpatients. Besides, the hazard rate (HR) was 0.543 (95%CI:0.328-0.898) for patients older than 70, 0.654 (95%CI:0.472-0.907) for patients without history of hepatitis B, and 0.585 (95%CI :0.423-0.810) for patients with TNM stage of I-II.
Results of DFS in different age groups, AJCC stage and with or without history of hepatitis B
As shown in Figure 1, the DFS of the different age groups were compared with Kaplan–Meier plot. The results indicated that patients with age≥70 have a longer DFS (P<0.05). As can be seen from the Kaplan-Meier curves, the survival rate in the young group showed the most significant downward trend in the first 6 months of follow-up, suggested that the patients in the young group had a greater risk of recurrence or even death within 6 months after surgery. Figures 3 and 5 showed DFS at different TNM stage and with or without a history of hepatitis B, respectively. From the figures, we found that the median DFS of the stage I-II group was 68 months, and the median DFS of the stage III- IV group was 12 months. patients with TNM stage of I-II and no history of hepatitis B had longer DFS ( P<0.05).
In order to investigate the association between TNM stage and the different age groups further，we performed survival analysis and results were shown in Figure 2A and Figure 2B. Figure 2A showed that in TNM stage of I-II, the elderly group possessed a longer DFS than the young group. However, there was no significant difference in TNM stage of III- IV. In addition, we also investigated the association between age and different TNM stage groups through Figure 4A and Figure 4B. The results suggested that the young group also had a better prognosis in TNM stage of I-II. In contrast, the difference was not statistically significant in the elderly group. Furthermore, the association between TNM stage and with or without history of hepatitis B was analyzed, however, no statistically significance was found.the association between TNM stage and with or without history of hepatitis B was analyzed in Figure 6A and Figure 6B, and no statistically significance was found.
The establishment and validation of prediction model
Based on the cox regression model, we used independent prognosis factors such as age, TNM stage, history of hepatitis B to establish a nomogram in Figure 7. Each clinicopathological feature of the patient was projected upward to obtain the corresponding score, which was then added to obtain the total score points. The predicted survival rate was correlated with the total points by drawing a vertical line from the Total Points scale to the 3-year or 5-year DFS scale.The C-index of this prediction model was calculated to be 0.604(95%CI:0.561-0.647) through 1000 times of bootstrap resampling method for internal validation, which suggested that this nomogram had good predictive value. The 3-year and 5-year DFS Calibration curve(Figure 8A and Figure 8B) show that the actual survival curve of the nomogram fits the predicted survival curve, indicating the model is reliable.