Demographics and basic characteristics

We extracted data from 2446 patients eligible for stage Ia HCC from the SEER database between 2004 and 2016. Table 1 presents the demographic and baseline characteristics of the patients included in this search. The age of the patients at the time of diagnosis varied between 20 and 90 years with 59 years as the median age. We further applied RCS with 3 nodes (5th, 50th, and 95th percentiles) to assess the association between age at diagnosis and all CODs (Fig. 2A). Based on the result, the appropriate inflection point for age at diagnosis was also 59. Of all enrolled patients, 1397 (57.1%) patients were married and 1049 (42.9%) patients with HCC were classified as single or other. A total of 1860 (76.0%) patients underwent cancer surgery. Only 64 (2.6%) patients with HCC were treated with RT. The correlation coefficient of the different variables is shown in Fig. S1. No factor was strongly correlated with other baseline characteristics. Additionally, it was observed that male patients had a significantly higher proportion of positive marital status than single and other patients (45.0% versus 29.4%, P

Table 1 Baseline characteristics of patients with stage Ia HCC.
Figure 2

(A) A restricted cubic spline (RCS) demonstrated that 59 years was a reasonable threshold. (B) OS and CSS of patients with stage Ia HCC. (VS) Cumulative risk curves according to marital status.

Survival results

The 5- and 10-year OS rates were 58.2% (95% CI, 0.560 to 0.604) and 45.8% (95% CI, 0.431 to 0.485), respectively, with a median duration of OS of 96.0 months (95% CI, 82,920–109,080, Figure 2B). Of the 2446 patients with HCC, 326 patients died from HCC-NDSD, such as other infectious and parasitic diseases including HIV (n=122), other causes of death (n=39), and heart disease (n = 38), accounting for 61.0% of the total (Fig. S2). Table 1 presents the baseline characteristics of HCC patients who died from HCC-DSD and HCC-NDSD. The 5- and 10-year CSS rates were 69.1% (95% CI, 0.669 to 0.713) and 60.6% (95% CI, 0.577 to 0.635), accordingly, with CSS time median not reached at time of analysis (Fig. 2B). In married patients, the median duration of OS was 130.0 ± 7.7 months (95% CI, 114.961–145.039) and in patients classified as single and other, the median duration of OS was 65 .0 ± 5.6 months (95% CI, 53.951–76.049) .

Fine gray regression analysis

Univariate analysis using the Fine-Gray test suggested that age at diagnosis (PP= 0.004), marital status (PPPP

Table 2 Univariate analysis in patients with stage Ia HCC using a competing risk model.

We then used the six variables that had statistical significance in the univariate analysis entered into the Fine-Gray model. According to the results of the Fine-Gray regression model, the age at diagnosis (PPP= 0.007, HR = 1.402, 95% CI: 1.095–1.795; well or moderately differentiated vs. unknown, P= 0.032, HR = 1.169, 95% CI: 1.014–1.349), surgical resection of the primary site (no/unknown vs yes, PP= 0.009, HR = 0.819, 95% CI: 0.706-0.952) all served as prognostic indicators significantly associated with OS independently (Table 3). In addition, the NDSD multivariate analysis also indicated that marital status (married vs. single and other, P

Table 3 Multivariate analysis of OS in patients with stage Ia HCC with Cox regression model and Fine-Gray regression model.

Cox regression analysis

According to the results of Cox regression analysis, four clinicopathologic characteristics, namely age at diagnosis, sex, tumor differentiation, marital status and a treatment-related parameter (primary site surgery) were significantly associated with OS (Table S2). The results recorded from the multivariate analysis showed that the significant covariates were age at diagnosis (PPP= 0.005, HR = 1.398, 95% CI: 1.106–1.767; well or moderately differentiated vs. unknown, P= 0.055 HR = 1.146, 95% CI: 0.997–1.318) and surgical resection of the primary site (no/unknown vs yes, P