Nomogram-based prognostic stratification for patients with large hepatocellular carcinoma: a population study of SEER database and a Chinese cohort
Original Article

Nomogram-based prognostic stratification for patients with large hepatocellular carcinoma: a population study of SEER database and a Chinese cohort

Kun Ji1, Hanlong Zhu2, Cong Zhang1, Jing Ai3, Li Jing1, Tiejian Zhao4, Hui Tao2, Feng Chen5, Wei Wu6,7

1Hepatobiliary and Pancreatic Interventional Treatment Center, Division of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; 2Department of Gastroenterology and Hepatology, Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China; 3Department of Ophthalmology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; 4Department of General Surgery, The Sixth People’s Hospital of Luoyang, Luoyang, China; 5Department of Radiology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; 6Department of Hepato-Pancreato-Biliary & Gastric Medical Oncology, Zhejiang Cancer Hospital, Hangzhou, China; 7Department of Medical Oncology, the Sixth People’s Hospital of Luoyang, Luoyang, China

Contributions: (I) Conception and design: K Ji, W Wu, F Chen; (II) Administrative support: H Zhu, J Ai; (III) Provision of study materials or patients: K Ji, H Zhu; (IV) Collection and assembly of data: C Zhang, J Ai; (V) Data analysis and interpretation: L Jing, W Wu, Hui Tao, T Zhao; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

Correspondence to: Wei Wu, MD, PhD. Department of Hepato-Pancreato-Biliary & Gastric Medical Oncology, Zhejiang Cancer Hospital, 1 Banshan East Road, Hangzhou 310000, China; Department of Medical Oncology, the Sixth People’s Hospital of Luoyang, Luoyang, China. Email: onco_wuwei@zju.edu.cn; Feng Chen, MD, PhD. Department of Radiology, the First Affiliated Hospital, Zhejiang University School of Medicine, 79 Qingchun Road, Hangzhou 310000, China. Email: chenfenghz@zju.edu.cn; Hui Tao, BSN. Department of Gastroenterology and Hepatology, Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, 305 Zhongshan East Road, Nanjing 210002, China. Email: taohui9008@163.com.

Background: Large hepatocellular carcinoma (HCC) with a diameter ≥5 cm remains a significant challenge of poor survival and raises the need for prognosis evaluation. This study aimed to develop and validate a nomogram-based prognostic stratification to assess overall survival (OS) of patients with large HCC.

Methods: Data of patients with large HCC were retrospectively collected from the Surveillance, Epidemiology, and End Results (SEER) database and our hospital, and were divided into the training cohort, internal validation cohort and external validation cohort. Cox analysis was performed to identify independent prognostic factors for the construction of nomogram in training cohort. The predictive ability of the nomogram was validated compared with the tumor node metastasis (TNM) classification staging system. Furthermore, prognostic stratification system based on nomogram was developed.

Results: Independent prognostic factors including histological grade, T stage, M stage, alpha fetoprotein (AFP), fibrosis score and surgery, were incorporated to construct nomogram. C-indexes of nomogram were 0.730, 0.726 and 0.724 in the training, internal and external validation cohorts, respectively. Importantly, nomogram harbored a superior discrimination and clinical benefit than the TNM staging system. Nomogram-based prognostic stratification divided patients into three groups: 345–414 (low-risk group), 415–460 (medium-risk group) and 461–513 (high-risk group). As shown in Kaplan-Meier curves, there were significant differences in OS among low-, medium- and high-risk groups (P<0.01).

Conclusions: Nomogram showed a superior prognostic predictive ability compared with the TNM staging system. The prognostic stratification serves as a valuable tool to assist clinicians on the selection of optimal treatment method and follow-up plan, particularly for the high-risk population.

Keywords: Hepatocellular carcinoma (HCC); survival; prediction; nomogram


Submitted Apr 19, 2024. Accepted for publication Aug 16, 2024. Published online Oct 08, 2024.

doi: 10.21037/jgo-24-288


Highlight box

Key findings

• The nomogram-based prognostic stratification for patients with large hepatocellular carcinoma (HCC) has been developed based on a large population and validated using a cohort of patients from our hospital.

What is known and what is new?

• Large HCC, defined as a tumor ≥5 cm in diameter, is associated with a poor survival due to increased potential of invasiveness, metastasis and challenge of surgical resection, raising the need for evaluation of prognosis for patients with large HCC.

• We identified the independent prognostic factors including histological grade, T stage, M stage, alpha fetoprotein, fibrosis score and surgery for patients with large HCC. Nomogram-based prognostic stratification divided patients into low-risk, medium-risk and high-risk groups. There were significant differences in overall survival among three risk groups.

What is the implication, and what should change now?

• Nomogram showed a superior predictive ability of survival compared with the tumor node metastasis classification staging. The prognostic stratification may serve as a valuable tool to assist clinicians on the selection of optimal treatment method and follow-up plan.


Introduction

According to the global cancer statistics, hepatocellular carcinoma (HCC) accounts for more than 75% of primary liver cancer, which is the fourth leading cause of cancer-related death worldwide (1). It is reported that the prognosis of patients with HCC is associated with the tumor size (2). Approximately 32% of HCC exhibit a tumor diameter exceeding 5 cm, with an additional 10–20% of tumors greater than 10 cm at the time of diagnosis (3). Guidelines from Asia-Pacific (4), Europe (5) and America (6) regard 5 cm as the cut-off to differentiate early and intermediate stage of HCC. Large HCC, defined as a tumor ≥5 cm in diameter, is associated with a poor survival due to increased potential of invasiveness, metastasis and challenge of surgical resection, raising the need for the evaluation of prognosis for patients with large HCC (7).

Currently, there are several staging systems widely applied to assess the outcome of HCC patients, such as the American Joint Committee on Cancer (AJCC), the Barcelona Clinic Liver Cancer system, the Okuda system. However, these staging systems have limited ability to predict survival for large HCC patients (8). For instance, the AJCC staging system only takes the tumor node metastasis (TNM) classification staging into account, without consideration of additional demographic and clinicopathologic characteristics, which may introduce sampling bias into the prognosis evaluation process (9). Other factors such as physical status of patients, liver function and tumor characteristics can also significantly affect the prognosis of patients (10). Therefore, there is a need for a comprehensive prognostic model that incorporates more significant factors, to assist clinicians in making decisions regarding treatment methods and follow-up plans.

As a graphical calculating model, nomogram has gained increasing interest and application in the diagnosis and prognosis of patients in several cancers such as melanoma, liver cancer and prostate cancer, through simply generating individual survival time or incidence probability by combining all risk factors for disease development (11-13). In the context of HCC, several nomograms have been devised for prognostic purposes; however, the majority of these nomograms were derived from a single population or lack validation with an independent cohort. To our knowledge, a prognostic nomogram for survival prediction in patients with large HCC has not yet been constructed.

This population-based study aimed to establish a reliable nomogram model to predict individual 3- and 5-year overall survival (OS) rates for patients with large HCC-based on a large cohort of population from the Surveillance, Epidemiology, and End Results (SEER) database. Furthermore, the predictive ability of nomogram model was validated compared with the TNM staging system, utilizing data from an external population of patients from our hospital. In addition, we conducted a risk stratification to enable clinicians to select optimal treatment methods and formulate follow-up strategy for patients with large HCC, especially for the high-risk population. We present this article in accordance with the TRIPOD reporting checklist (available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-288/rc).


Methods

Patients

Data of patients were retrospectively collected from SEER database and the First Affiliated Hospital, Zhejiang University School of Medicine. Information on patients with HCC between 2004 and 2015 were extracted from the SEER database using SEER Stat software (version 8.4.0; NCI, Bethesda, MD, USA) (14). The International Classification of Diseases for Oncology (ICD-O-3 code: 8170, 8171, 8172, 8173, 8174 and 8175) and site codes C22.0 (liver) were used to screen out HCC patients. Inclusion criteria were as follows: (I) HCC as the primary tumor; (II) tumor diameter ≥5 cm; and (III) available demographic characteristics (age, gender, race, insurance and marital status), tumor-related factors [tumor size, histological grade, 6th TNM staging, alpha fetoprotein (AFP), fibrosis score], treatment (surgery, radiation and chemotherapy) and survival information. Exclusion criteria were as follows: (I) age ≤18 years and (II) diagnosis of HCC by death certificate or autopsy. Fibrosis score was scored as 0–4 (none or moderate fibrosis) and 5–6 (severe fibrosis or cirrhosis). There were three categories for treatment including none (no tumor-directed surgery), local tumor destruction (such as photodynamic therapy and cryosurgery) and resection (partial or total hepatectomy).

As for extracting patients from our center, we included 302 patients with large HCC from May 2019 to March 2021 as the external validation cohort. The following inclusion criteria were adopted: (I) aged more than 18 years; (II) diagnosis of HCC with tumor diameter ≥5 cm; (III) no severe chronic diseases; (IV) no other tumor history; and (V) complete data such as tumor size, AFP, treatment, and follow-up information. In cases where tumor resection was not performed, imaging modalities including contrast-enhanced ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) were utilized to assess tumor size and T stage, N stage and M stage. Moreover, the variable of AFP was divided into normal and elevated. OS was computed from the date of diagnosis to death or the last follow-up. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the ethics committee of the First Affiliated Hospital, Zhejiang University School of Medicine (No. 2016-324) and individual consent for this retrospective analysis was waived.

Construction of nomogram-based prognostic stratification

Patients from SEER database were randomly divided into the training cohort and internal validation cohort in a ratio of 7:3. In training cohort, univariate Cox regression analysis was performed to identify the association between OS and variables such as age, gender, tumor size, histological grade, TNM staging, AFP, fibrosis score, surgery and chemotherapy. Subsequently, variables with P value <0.05 in univariate analysis were included in multivariable analysis to determine the independent prognostic indicators. Based on the independent prognostic factors, a nomogram was constructed to predict 3- and 5-year survival rates for patients with large HCC.

The discrimination and calibration of nomogram were assessed by the internal and external validation cohorts compared with TNM staging system. Specifically, the concordance index (C-index) was adopted to evaluate the discriminative ability, though quantifying the discrepancies between observed and predicted outcomes, and higher C-index value meant more accurate prediction (15). Furthermore, calibration plots were applied to reflect the consistency between the actual and predicted survival probabilities. The discrimination of TNM staging system and nomogram was compared via the area under receiver operating characteristic (ROC) curve (AUC). Decision curve analysis (DCA) was used to determine the clinical benefit of nomogram. In addition, the total point of each patient was calculated according to score assignment of variables in the nomogram. Subsequently, a nomogram-based prognostic stratification system was developed to separated patients into high-, middle-, and low-risk groups. Kaplan-Meier (K-M) curves were drawn to estimated visually survival difference among the three risk groups.

Statistical analysis

All statistical analyses were performed using SPSS software (IBM Corporation, USA, version 26) and programming language R (version 3.6.2). Univariable and multivariable Cox regression analyses were conducted to identify the independent predictors associated with OS. Only the variables with P values <0.05 in univariable analysis were subsequently included in multivariable analysis. The cutoff values of the total points from nomogram were determined by X-tile program (Yale University, New Haven, CT, USA). Besides, the survival differences among three groups were estimated by log-rank test. C-index, ROC curves, nomogram, calibration curves, DCA curves and K-M curves were generated in R with packages “rms”, “survival”, “foreign”, “timeROC” and “regplot”. Statistical significance was set as P<0.05 in a two-sided test.


Results

Patient characteristics

A total of 1,426 patients with large HCC from SEER database were eventually included and randomly divided into the training cohort (n=1,012) for nomogram construction and internal validation cohort (n=414) for internal verification. An independent cohort of 302 patients from our center formed the external validation cohort. The detailed process of patient selection is shown in Figure 1. Since the diagnosis of HCC mainly relies on imaging test, unknown histological grade accounted for the majority of HCC. There were more patients treated with local tumor destruction while a smaller proportion received chemotherapy in our center than SEER database. More clinicopathologic characteristics of patients in three cohorts are listed in Table 1.

Figure 1 Flow diagram of the selection criteria of patients with large hepatocellular carcinoma. SEER, Surveillance, Epidemiology, and End Results database; HCC, hepatocellular carcinoma; TNM, tumor node metastasis staging; AFP, alpha fetoprotein.

Table 1

Demographic and clinical characteristics of patients with large HCC

Characteristics Training cohort (n=1,012) Internal validation cohort (n=414) External validation cohort (n=302)
Age, years 62.43±11.87 62.22±11.58 55.10±10.61
Gender
   Female 217 (21.4) 92 (22.2) 45 (14.9)
   Male 795 (78.6) 322 (77.8) 257 (85.1)
Race
   White 632 (62.5) 250 (60.4) NA
   Black 127 (12.5) 58 (14.0) NA
   Other 253 (25.0) 106 (25.6) 302 (100.0)
Insurance status
   No 24 (2.4) 12 (2.9) 13 (4.3)
   Yes 841 (83.1) 334 (80.7) 279 (92.4)
   Unknown 147 (14.5) 68 (16.4) 10 (3.3)
Marital status
   Single 370 (36.6) 147 (35.5) 33 (10.9)
   Married 607 (60.0) 256 (61.8) 269 (89.1)
   Unknown 35 (3.5) 11 (2.7) 0
Histological grade
   Well/moderate 274 (27.1) 112 (27.1) 57 (18.9)
   Poor/undifferentiated 111 (11.0) 39 (9.4) 35 (11.6)
   Unknown 627 (62.0) 263 (63.5) 210 (69.5)
Tumor size, mm 92.88±67.10 94.77±61.78 85.92±39.75
TNM stage
   I 353 (34.9) 125 (30.2) 87 (28.8)
   II 121 (12.0) 48 (11.6) 33 (10.9)
   III 420 (41.5) 201 (48.6) 123 (40.7)
   IV 118 (11.7) 40 (9.7) 59 (19.5)
T stage
   T1 382 (37.7) 137 (33.1) 93 (30.8)
   T2 129 (12.7) 56 (13.5) 35 (11.6)
   T3 447 (44.2) 196 (47.3) 75 (24.8)
   T4 54 (5.3) 25 (6.0) 99 (32.8)
N stage
   N0 924 (91.3) 383 (92.5) 272 (90.1)
   N1 88 (8.7) 31 (7.5) 30 (9.9)
M stage
   M0 894 (88.3) 374 (90.3) 268 (88.7)
   M1 118 (11.7) 40 (9.7) 34 (11.3)
AFP
   Normal 313 (30.9) 123 (29.7) 153 (50.7)
   Elevated 699 (69.1) 291 (70.3) 149 (49.3)
Fibrosis score
   0–4 416 (41.1) 177 (42.8) 113 (37.4)
   5–6 596 (58.9) 237 (57.2) 189 (62.6)
Surgery
   None 497 (49.1) 201 (48.6) 59 (19.5)
   Local destruction 63 (6.2) 26 (6.3) 139 (46.0)
   Resection§ 452 (44.7) 187 (45.2) 104 (34.5)
Radiation
   No 987 (97.5) 404 (97.6) 289 (95.7)
   Yes 25 (2.5) 10 (2.4) 13 (4.3)
Chemotherapy
   No/unknown 567 (56.0) 224 (54.1) 266 (88.1)
   Yes 445 (44.0) 190 (45.9) 36 (11.9)

Data are presented as mean ± standard deviation or number (percentage). , other: American Indian/Alaska Native and Asian/Pacific Islander. , local destruction: photodynamic therapy, electrocautery, fulguration, cryosurgery, laser, percutaneous ethanol injection, thermal ablation, ultrasound and acetic acid. §, resection: partial and total hepatectomy. TNM, tumor node metastasis staging; AFP, alpha fetoprotein; HCC, hepatocellular carcinoma; NA, not applicable.

Independent prognostic factors

Univariate Cox analyses revealed that age, race, histological grade, AJCC stage, T stage, N stage, M stage, AFP, fibrosis score, surgery and chemotherapy were significantly associated with OS in the training set. It is worth mentioning that AJCC stage was not involved in subsequent multivariate analysis due to its dependence from T, N and M stages. Multivariate Cox analysis demonstrated that histological grade, T stage, M stage, AFP, fibrosis score, surgery and chemotherapy were independent prognostic factors of OS (Table 2). As for chemotherapy, there are many different types of chemotherapy with varied therapeutic effects, and it is unclear which chemotherapy drug was used in SEER database. Therefore, chemotherapy is excluded as independent prognostic factor in the following analysis.

Table 2

Univariate and multivariate Cox regression analyses of overall survival for patients with large HCC

Characteristics Univariate analysis Multivariate analysis
HR 95% CI P value HR 95% CI P value
Age 1.009 1.003–1.015 0.005
Gender
   Female Reference
   Male 1.177 0.981–1.411 0.07
Race
   White Reference
   Black 0.920 0.734–1.153 0.46
   Other 0.766 0.641–0.914 0.003
Insurance status
   No Reference
   Yes 0.732 0.464–1.157 0.18
   Unknown 0.797 0.492–1.293 0.35
Marital status
   Single Reference
   Married 0.870 0.747–1.012 0.07
   Unknown 0.931 0.618–1.402 0.73
Histological grade
   Well/moderate Reference Reference
   Poor/undifferentiated 1.394 1.145–1.698 0.001 1.754 1.410–2.164 <0.001
   Unknown 0.921 0.773–1.098 0.36 1.266 1.054–1.521 0.01
Tumor size 1.001 1.000–1.002 0.051
TNM stage
   I Reference
   II 1.034 0.786–1.359 0.81
   III 1.872 1.575–2.225 <0.001
   IV 3.590 2.836–4.544 <0.001
T stage
   T1 Reference Reference
   T2 1.037 0.801–1.343 0.78 1.254 0.959–1.640 0.09
   T3 1.896 1.608–2.237 <0.001 1.394 1.174–1.654 <0.001
   T4 2.378 1.746–3.238 <0.001 1.375 0.991–1.907 0.057
N stage
   N0 Reference
   N1 2.407 1.897–3.055 <0.001
M stage
   M0 Reference Reference
   M1 2.632 2.139–3.240 <0.001 1.615 1.297–2.011 <0.001
AFP
   Normal Reference Reference
   Elevated 1.657 1.405–1.956 <0.001 1.378 1.161–1.635 <0.001
Fibrosis score
   0–4 Reference Reference
   5–6 1.593 1.368–1.854 <0.001 1.245 1.062–1.459 0.007
Surgery
   None Reference Reference
   Local destruction 0.429 0.318–0.577 <0.001 0.427 0.314–0.579 <0.001
   Resection§ 0.270 0.229–0.318 <0.001 0.235 0.192–0.287 <0.001
Radiation
   No Reference
   Yes 0.856 0.521–1.406 0.53
Chemotherapy
   No/unknown Reference Reference
   Yes 1.241 1.072–1.437 0.004 0.636 0.541–0.747 <0.001

, other: American Indian/Alaska Native and Asian/Pacific Islander. , local destruction: photodynamic therapy, electrocautery, fulguration, cryosurgery, laser, percutaneous ethanol injection, thermal ablation, ultrasound and acetic acid. §, resection: partial and total hepatectomy. HR, hazard ratio; CI, confidence interval; AFP, alpha-fetoprotein; HCC, hepatocellular carcinoma; TNM, tumor node metastasis staging.

Development and validation of nomogram

A nomogram model integrating the independent prognostic factors was established for prediction of 3- and 5-year survival rates for patients with large HCC in the training set (Figure 2). As nomogram showed, surgery made the largest contribution, followed by histological grade, M stage, AFP, fibrosis score and T stage. Each level of the variables is assigned a score on the Points scale in the light of its prognostic value, and the total point can be simply acquired by summing the score of each factor. The sizes of the blue boxes in the middle and the yellow block on the total points axis represented the proportion of patients. The score assignment for variables included in nomogram is shown in Table 3. For instance, as shown in Figure 2, if a patient presented with a fibrosis score of 0–4 (69 points), an elevated AFP level (84 points), histological grade poor/undifferentiated (100 points), T2 stage (80 points) and M1 stage (95 points), and subsequently undergone surgical resection (0 points), his/her total point amounted to 428. This point corresponded to an estimated 3- and 5-year survival rates of 28.0% and 15.8%, respectively. Total points and survival rate in the nomogram were shown in Table 4. Furthermore, an online version of nomogram was provided at https://jikun.shinyapps.io/large_hcc (Figure 3), so as to enable calculation easy and avoid the manual calculation errors.

Figure 2 Nomogram for predicting prognosis of patients with large hepatocellular carcinoma. Each category of the prognostic variables is assigned a score on the points scale. The sum of these scores is located on the total points scale and a line is drawn downward to determine the specific probability of 3- and 5-year overall survival. AFP, alpha fetoprotein.

Table 3

Score assignment for variables included in the nomogram

Characteristics Points
AFP
   Normal 69
   Elevated 84
Fibrosis score
   0–4 69
   5–6 79
T stage
   T1 69
   T2 80
   T3 86
   T4 85
M stage
   M0 69
   M1 95
Histological grade
   Well/moderate 69
   Unknown 83
   Poor/undifferentiated 100
Surgery
   None 69
   Local destruction 25
   Resection§ 0

, local destruction: photodynamic therapy, electrocautery, fulguration, cryosurgery, laser, percutaneous ethanol injection, thermal ablation, ultrasound and acetic acid. §, resection: partial and total hepatectomy. AFP, alpha fetoprotein.

Table 4

Total points and survival rate in the nomogram

Time Survival rate, %
10 20 30 40 50 60 70 80
3 years 459 440 424 410 395 378 360 335
5 years 439 420 405 390 375 359 340
Figure 3 Layout of an online version of the developed nomogram (https://jikun.shinyapps.io/large_hcc). The black line stands for the estimated survival probability of the patients with a fibrosis score of 0–4, normal AFP level, unknown histological grade, T1 and M0 stage, and no surgery. The blue line stands for those with a fibrosis score of 5–6, normal AFP level, well/moderate histological grade, T1 and M0 stage, and undergoing local tumor destruction. AFP, alpha fetoprotein.

C-indexes of nomogram were 0.730 (95% CI, 0.712–0.748) in the training cohort, 0.726 (95% CI, 0.695–0.757) in the internal validation cohort, and 0.724 (95% CI, 0.677–0.771) in the external validation cohort, manifesting accurate capability in prognosis prediction. The calibration curves for probability of survival at 3 and 5 years exhibited excellent agreement between the actual and predicted observation in three cohorts (Figure 4). Meanwhile, AUCs of nomogram in ROC curves revealed superior discrimination in comparison to that of AJCC TNM staging [training cohort: 3-year survival (0.799 vs. 0.675) and 5-year survival (0.811 vs. 0.676); internal validation cohort: 3-year survival (0.834 vs. 0.683) and 5-year survival (0.873 vs. 0.712); external validation cohort: 3-year survival (0.843 vs. 0.720) and 5-year survival (0.790 vs. 0.685)] (all P<0.01) (Figure 5). Importantly, DCA curves showed that nomogram gained more clinical benefits than TNM staging for predicting OS at 3 and 5 years in three cohorts (Figure 6).

Figure 4 Calibration curves of nomogram for predicting overall survival at 3- and 5-year in the training cohort (A), internal validation cohort (B) and external validation cohort (C), respectively.
Figure 5 ROC curves of nomogram and TNM staging for predicting overall survival at 3- and 5-year in the training cohort (A,B), internal validation cohort (C,D) and external validation cohort (E,F), respectively. ROC, receiver operating characteristic curve; AUC, areas under the curve; TNM, tumor node metastasis staging.
Figure 6 Decision curves of nomogram and TNM staging for clinical utility of overall survival at 3- and 5-year in the training cohort (A,B), internal validation cohort (C,D) and external validation cohort (E,F), respectively. TNM, tumor node metastasis staging.

Construction of prognostic stratification

The median survival time was 19, 17 and 25 months in the training, internal validation and external validation cohorts, respectively. Based on the total points calculated from nomogram, patients were divided into three groups: 345–414 (low-risk group), 415–460 (medium-risk group) and 461–513 (high-risk group). The median OS of patients in low-risk, medium-risk and high-risk group were 45, 14 and 5 months in the training set; 45, 12 and 4 months in the internal validation set; >45, 19 and 8.6 months in the external validation set, respectively. K-M curves of three risk groups were clearly separated in three cohorts (P<0.01), which implied a stronger correlation between lower risk and longer OS (Figure 7).

Figure 7 Kaplan-Meier curves for comparing different risk groups of patients with large hepatocellular carcinoma in the training cohort (A), internal validation cohort (B) and external validation cohort (C).

Discussion

Advances in imaging modalities and health monitoring strategy in high-risk population have facilitated the early detection of HCC, leading to improved outcomes in terms of OS (16). However, large HCC with a diameter ≥5 cm is frequently diagnosed at an advanced stage, presenting a challenge to clinicians because of high likelihood of microvascular invasion, satellite nodules, recurrence and metastasis (17,18). Previous studies have revealed that some factors such as cirrhosis, vascular invasion and treatment are associated with OS in patients with large HCC (9,19). Nevertheless, until now, there is limited study having developed nomogram to predict outcomes for large HCC. In the present study, we developed and validated a nomogram model based on a large population from SEER database and an independent cohort of patients from our center to accurately estimate individual 3- and 5-year survival probabilities for patients with large HCC. The nomogram showed excellent discrimination and calibration of valuable consistencies between the prediction and observation especially in the external validation cohort, indicating a superior external utility of nomogram.

Although the AJCC TNM staging has been widely applied to determine treatment method and expected survival for HCC patients (6), there is still controversy regarding its ability in predicting prognosis (8,12). This nomogram exhibited a superiority over the TNM staging system in predictive ability of prognosis, with a higher AUCs in internal and external validation cohorts. In DCA curves, improved clinical value of nomogram was observed compared with the TNM staging system. These results clearly illustrated considerable difference between the TNM staging based on T, N, and M stages solely and nomogram model integrating various significant clinicopathological factors for prognoses prediction of patients with large HCC.

Liver fibrosis, as a result of chronic liver injury, makes a considerable contribution to the formation of cirrhosis and HCC (20). Accordingly, the current study illustrated a correlation between the worsening prognosis and increasing fibrosis degree, potentially attributed to the advancement of fibrosis leading to liver failure, hepatic encephalopathy, and portal hypertension (21,22). Moreover, the tumor resection rate of patients with none or moderate fibrosis was over twice that of those with severe fibrosis or cirrhosis in this study (64.7% vs. 30.6%, P<0.01), indicating that the severity of fibrosis may impact patient survival by influencing the selection of treatment.

In accordance with findings of Liu et al. (23), the level of AFP turned out to be an independent prognostic factor for large HCC. Two staging system, Cancer of the Liver Italian Program (CLIP) (24) and Chinese University Prognostic Index (CUPI), have emphasized and incorporated the preoperative AFP levels into prognostic assessment. The underlying rationale for the correlation between increased levels of AFP and poorer prognosis remains unclear (25). Studies found that a high level of AFP was related to the dysfunctional antigen-presenting cells and the impaired dendritic cells in patients with HCC (26,27), and this interaction between AFP and the immune system may account for poor outcomes.

It was observed that histological grade, a indicator of biological aggressiveness of HCC, had a stronger correlation with tumor recurrence and survival (12,28). In this study, the median survival of patients with histological grade of well/moderate and poor/undifferentiated were 22 and 9 months, respectively (P<0.01), illustrating that degree of differentiation of tumor posed significant influence on prognosis. Furthermore, our study found that the tumor metastasis rate of poor differentiation was significantly higher than that of well differentiation (19% vs. 9.1%, P<0.01), indicting an increased invasiveness and metastatic nature of poor differentiation. Surgery plays a most important role in impacting prognosis in our study. Although surgical resection remains the mainstay of curative treatment for HCC, only 41% of patients are candidates for hepatectomy because of decompensated liver function, vascular invasion and metastasis (29-31), in accordance with fewer than half of the cases had undergone hepatectomy in this study. When it comes to unresectable HCC, the optional therapy includes radiofrequency ablation (RFA) and transcatheter arterial chemoembolization (TACE) (32).

In addition, prognostic stratification system including high-, middle-, and low-risk groups was constructed based on the total scores from nomogram. As shown in the K-M curves, the population at high risk was significantly associated with poor prognosis. The prognostic stratification system may be helpful to formulate individual therapy method and follow-up plan according to the different risk groups. The patients at low risk could have more treatment options based on liver function and tumor status; for patients at medium risk, a combination of targeted therapy or immunotherapy may be recommended to improve survival; patients at high risk may need palliative treatment. For patients deemed to be at high risk, it is recommended that the follow-up interval should be shortened and adjusted according to tumor status. Conversely, for patients classified as low risk group, the follow-up interval may be prolonged appropriately.

There are some limitations in the present study. First, the retrospective design of the study may lead to unavoidable selection bias. Second, nomogram did not include prognostic predictors such as liver function, since information of liver function was unavailable in SEER database. Besides, another limitation was a lack of validation using data of patients from other countries, though we have confirmed the reliable predictive power of nomogram-based prognostic stratification in Chinese patients. Therefore, further multicenter studies should be warranted in order to verify the prognostic stratification worldwide.


Conclusions

In summary, this study proposed a nomogram model on basis of a large population to predict 3- and 5-year survival rates for patients with large HCC, which showed preferable prediction ability in comparison with the TNM staging. Furthermore, nomogram-based prognostic stratification was developed as a valuable tool to assist clinicians on the selection of optimal treatment method and follow-up plan, particularly for high-risk population.


Acknowledgments

We sincerely thank the Surveillance, Epidemiology, and End Results (SEER) program for the efforts in providing high-quality open resources.

Funding: This study was supported by the National Natural Science Foundation of China (Nos. 82102159, 82102160, 12090020, and 12090025), and Zhejiang Provincial Natural Science Foundation Committee-Zhejiang Society for Mathematical Medicine Joint Fund Major Project (No. LSD19H180003).


Footnote

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Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-288/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the ethics committee of the First Affiliated Hospital, Zhejiang University School of Medicine (No. 2016-324) and individual consent for this retrospective analysis was waived.

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Cite this article as: Ji K, Zhu H, Zhang C, Ai J, Jing L, Zhao T, Tao H, Chen F, Wu W. Nomogram-based prognostic stratification for patients with large hepatocellular carcinoma: a population study of SEER database and a Chinese cohort. J Gastrointest Oncol 2024;15(5):2201-2215. doi: 10.21037/jgo-24-288

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