Keywords
Meta-analysis, Pancreatic neoplasms, Survival, Young adult
In recent years, the incidence of early-onset pancreatic cancer (EOPC) has increased. Several studies comparing the survival of patients with EOPC to those with average-onset pancreatic cancer (AOPC) have reported mixed results. We aimed, therefore, to perform a meta-analysis summarizing the current evidence.
We searched the MEDLINE and EMBASE databases for relevant articles published through March 2024. Articles comparing the survival of patients with EOPC – defined as pancreatic ductal adenocarcinoma (PDAC) diagnosed at ≤ 50 years of age – and AOPC were included in the present meta-analysis. The primary outcome was the pooled adjusted hazard ratio (aHR), and the risk of bias analysis was performed using the Quality in Prognostic Factor Studies tool. The meta-analysis was performed using a random-effects model.
A total of 17 studies were eligible for the primary analysis, the results of which indicated that patients with EOPC had a longer overall survival than those with AOPC (aHR = 0.80; 95% confidence interval [CI], 0.74–0.86; P < 0.001). The rate of distant metastasis was higher in EOPC than AOPC; however, patients with EOPC also received more treatments than those with AOPC.
Patients with EOPC had a better prognosis than those with AOPC. Clinicians must ensure that patients with PDAC receive early and appropriate treatment to improve their survival.
Meta-analysis, Pancreatic neoplasms, Survival, Young adult
As of 2022, pancreatic cancer is the 12th most common type of cancer and the 6th largest contributor of cancer-related mortality worldwide, with a relative 5-year survival rate of 12.5%.1 According to the Surveillance, Epidemiology, and End Results (SEER) database, the median age of patients diagnosed with pancreatic cancer is 70 years old2; however, the number of younger patients diagnosed with pancreatic cancer, termed early-onset pancreatic cancer (EOPC), is increasing.3
There is no consensus regarding the definition of EOPC as it pertains to age; however, it is largely used to describe patients who are ≤ 50 years of age when diagnosed with pancreatic cancer.4–7 Additionally, pancreatic cancer that is diagnosed at age < 45 years old is occasionally defined as very early-onset pancreatic cancer (VEOPC).8 EOPC accounts for 0.87–11.50% of pancreatic cancers, depending on the study population.9,10 Although EOPC occurs more often in males, the age-adjusted incidence rate increased significantly more in young females than their male counterparts.11 Several risk factors have been associated with EOPC, including heavy alcohol consumption, smoking, family history of pancreatic cancer, diabetes mellitus, obesity, and pancreatitis.12 Some studies also showed unique molecular profiles in patients with EOPC, such as a higher frequency of wild-type KRAS and higher mutation rates of CDKN2A, SMAD4, and FOXC2.13 Although the effects of these genomic alterations on tumor behavior are still unclear, some studies have shown that patients with EOPC often present with higher rates of distant metastasis.14
Studies investigating differences in survival times between patients with early-onset PDAC and those with average-onset PDAC (AOPC) have shown conflicting results. Several studies have shown that patients with EOPC have a better prognosis than those with AOPC4,15; however, some studies have shown that patients with EOPC have a worse survival than those with AOPC.9,14 Additionally, some studies did not find any significant difference in survival between patients with EOPC and those with AOPC.5,7 To the best of the authors’ knowledge, however, a meta-analysis on this topic has not yet been performed. In the present study, therefore, we conducted a meta-analysis of studies that compared the survival rates of patients with EOPC to those with AOPC, specifically focusing on pancreatic ductal adenocarcinoma (PDAC), which is the most common type of pancreatic cancer (approximately 90%).16
The present systematic review and meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist.17
We used the PICOTS framework18 to define the review questions, as follows: Population = patients with PDAC; Index Prognostic Factor = EOPC; Comparator Prognostic Factor = adjusted for cancer stage/resectability status/tumor size; Outcome = Survival; Timing = age at diagnosis; Setting = all care settings. Based on the review question, the inclusion criteria were as follows: 1) studies that compared the overall survival between patients with EOPC and those with AOPC, although to maximize the number of studies included, if only cancer-specific survival were available, studies were still accepted; 2) studies that defined EOPC as patients who were diagnosed with PDAC at ≤ 50 years of age (although various definitions of EOPC are used in the relevant literature, we chose this cut-off because it was the most frequently used definition in the literature4–7,9,14,19–24; by this definition, studies that used a cut-off of 45 or 40 years of age were also included, and the comparator group in each study was categorized as the AOPC group); and 3) survival analysis must be adjusted to the tumor stage (either by regression analysis or matching) – if the American Joint Committee on Cancer (AJCC) cancer stage25 was unavailable, we also accepted survival analysis, which was adjusted for tumor resectability or tumor size to maximize the number of studies included. The exclusion criteria were as follows: 1) studies with only abstracts available; 2) studies that did not present a hazard ratio and were inestimable from other values by the methods described by Tierney et al.26 and Hebert et al.27; and 3) studies that were not available in English.
Two independent reviewers searched the MEDLINE and EMBASE databases for articles published through March 2024. For MEDLINE, the following search terms were used: (early-onset pancreatic cancer [Title/Abstract]) OR ((young [Title/Abstract] AND pancreatic cancer [Title/Abstract])). For EMBASE, the following terms were used: ‘early-onset pancreatic cancer’:ab,ti OR (young:ab,ti AND ‘pancreatic cancer’:ab,ti). We also reviewed the reference lists of related papers to identify additional studies.
Two independent reviewers extracted the data from included studies using the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prognostic Factor Studies (CHARMS-PF).18 The following data were extracted: authors; year of study; study design; definition of EOPC and AOPC; number of subjects; period of recruitment; evaluation of survival; median follow-up; adjustment to other variables; hazard ratio; rate of distant metastasis; and proportion of subjects who received surgery, chemotherapy, or radiotherapy. Additionally, the risk of bias for each study was analyzed using the Quality in Prognostic Factor Studies (QUIPS) tool,28 which evaluates the following aspects: adequate study participation; study attrition; prognostic factor measurement; outcome measurement; adjustment for other prognostic factors; and statistical analysis and reporting. Permission has been obtained from the creator to use the QUIPS tool.
The Review Manager (RevMan) 5.3 program (The Nordic Cochrane Center, Copenhagen, Denmark)29 and R 4.3.2 program (R Core Team, Vienna, Austria)30 were used to perform the meta-analysis. The primary outcome was overall survival. The adjusted hazard ratio (aHR) for each study was used in the pooled analysis and presented as forest plots. If there was a study in which survival analysis was stratified based on cancer stage or resectability, multiple hazard ratios were first pooled into one value. If the aHR was not stated, it was estimated using the methods described by Tierney et al.26 and Hebert et al.27 If there was substantial heterogeneity between the studies, we used a random effects analysis to calculate the pooled aHR, otherwise, a fixed-effects analysis was used. Additionally, we performed a pooled hazard ratio analysis for cancer-specific survival (CSS), disease-free survival (DFS), progression-free survival (PFS), and recurrence-free survival (RFS).
We also performed sensitivity analyses, based on the type of survival analysis, age cutoff, presence of matching, regression analysis, published hazard ratio only, and adjustment for several covariates, as well as a subgroup analysis of the patients who underwent surgery. Publication bias was assessed using funnel plots, and Egger’s test was performed using ProMeta 3 (Internovi, Cesena, Italy).31 Additionally, we calculated the pooled risk ratios for the rates of distant metastasis (stage IV cancer) and treatment (surgery, chemotherapy, and radiotherapy).
The PRISMA study flow diagram is shown in Figure 1. A total of 522 records were initially obtained from MEDLINE, EMBASE, and the reference lists of the eligible studies, after the removal of duplicates, of which 46 were assessed for eligibility. Articles that only included patients with EOPC or used different age cutoffs for EOPC (e.g., age < 55, < 60, or < 70 years) were excluded. Table S1 shows a list of the excluded studies and the reasons for their exclusion. In total, 17 studies were included in the final analysis.
Table 1 shows the characteristics of the 17 studies included in the present meta-analysis. The total number of patients with EOPC was 33,274 subjects, while that of those with AOPC was 563,198.
Table 2 shows the risk of bias for the 17 studies included in the present meta-analysis.
Overall survival (OS)
Figure 2 shows the forest plot of the OS analysis of the studies included in the present meta-analysis. The patients with EOPC had a better OS than those with AOPC (aHR = 0.80; 95% confidence interval [CI], 0.74–0.86; P < 0.001). The range of median survival for EOPC subjects was 5.7─36.0 months, while the range of median survival for AOPC patients was 4.0─32.0 months.
The sensitivity analysis is shown in Table 3.
The funnel plot for OS analysis is shown in Figure S1. Egger’s test showed no significant publication bias (P = 0.227).
We also performed a pooled analysis of studies that included other types of survival analyses. Pooled CSS analysis (n = 4), as seen in Figure S2, showed that patients with EOPC had a better CSS than those with AOPC (HR = 0.85; 95% CI, 0.72–1.00; P = 0.05). Pooled RFS analysis (n = 4), as seen in Figure S3, showed that patients with EOPC had a similar RFS to those with AOPC (HR = 1.10; 95% CI, 0.78–1.54; P = 0.60). The pooled PFS (n = 3), as seen in Figure S4, also showed that patients with EOPC had a similar PFS to those with AOPC (HR = 0.84; 95% CI, 0.61–1.17; P = 0.30). Only one study reported DFS, which showed that patients with EOPC had a worse DFS than those with AOPC (HR = 2.40; 95% CI, 1.13–5.10; P = 0.02).32
Overall survival in patients undergoing surgery
Figure 3 shows the forest plot for studies that performed subgroup OS analyses in patients undergoing surgery (n = 9), the result of which showed that patients with EOPC who underwent surgery had a similar OS to those with AOPC who underwent surgery (aHR = 0.95; 95% CI, 0.84–1.08; P = 0.44).
Figure S5 shows the pooled analysis of the risk ratio (RR) of distant metastasis between patients with EOPC and those with AOPC. Twelve studies were included in the pooled analysis, the results of which showed that patients with EOPC had an increased risk of distant metastasis (stage IV) than those with AOPC (RR = 1.08; 95% CI, 1.03–1.13; P = 0.001).
Surgery
Figure S6 shows the pooled analysis of the RR of the rate of surgery between patients with EOPC and those with AOPC, the results of which showed that patients with EOPC underwent more surgeries than those with AOPC (RR = 1.22; 95% CI, 1.13–1.32; P < 0.001).
Chemotherapy
Figure S7 shows the pooled analysis of the RR of the rate of chemotherapy between patients with EOPC and those with AOPC, the results of which showed that patients with EOPC received more chemotherapy than those with AOPC (RR = 1.31; 95% CI, 1.25–1.37; P < 0.001).
Radiotherapy
Figure S8 shows a pooled analysis of the RR of the rate of radiotherapy between patients with EOPC and those with AOPC, the results of which showed that patients with EOPC underwent more radiotherapy than those with AOPC (RR = 1.35; 95% CI, 1.32–1.38; P < 0.001).
The relationship between age at diagnosis and the survival of patients with cancer is complex. Some studies have shown that early-onset breast, lung, central nervous system, and soft tissue cancers are associated with poor prognosis.33,34 Other studies, however, have shown that patients with early-onset cancer had a better OS than those with late-onset cancer, such as colorectal cancer.35 The results of our meta-analysis fall in line with the latter, showing that EOPC patients had better prognosis than AOPC patients. Our findings are in line with the results of most previous studies. For example, Beeghly-Fadiel et al.9 showed that patients with EOPC had a better OS than those with AOPC, independent of other factors. They also showed that the mortality rate increased significantly after the age of 60 years in patients with EOPC. A study by Ordonez et al.14 showed similar results. Although patients with EOPC presented with several risk factors that are typically associated with worse survival (e.g., more advanced stage, male sex, and non-caput tumor), they still had a better OS than patients with AOPC.
Several other studies, however, have reported contradictory results. Ansari et al.4 analyzed 72,906 patients with PDAC from the SEER registry, and after propensity score matching, found that patients with EOPC had a shorter CSS than those with AOPC. This result was true even after controlling for other factors, such as cancer stage and treatment received by the patients. They also found that patients with EOPC were also more often diagnosed at more advanced AJCC stages and received more treatments (surgery, radiotherapy, and chemotherapy) than patients with AOPC. Another registry-based study in Japan also found that younger patients had worse survival rates than older patients. Similarly, the aforementioned study showed that younger patients were often diagnosed at more advanced stages than older patients; however, they found that younger patients underwent fewer surgeries and achieved fewer R0 resections than older patients. When subgroup analysis of resected patients was performed, there was no difference in the survival rates between younger and older patients.15 The aforementioned study was not included in the pooled analysis, however, because the survival analysis was not adjusted for cancer stage.
The pooled analysis in the present study also showed that patients with EOPC had a higher rate of distant metastasis than those with AOPC, a phenomenon which was also observed in previous studies. For example, Tingstedt et al.7 found a higher proportion of distant metastasis in patients with EOPC than in those with AOPC. Eguchi et al.15 found that patients with EOPC had a larger tumor size, liver metastasis, and peritonitis carcinomatosa than those with AOPC. It is still unclear why patients with EOPC are more often diagnosed at an advanced cancer stage compared to patients with AOPC. One potential explanation for this might be the underdiagnosis of cancer in younger patients, as clinicians may be less likely to diagnose rare pathologies in younger patients, particularly in the early stages of the disease. Additionally, younger patients are more likely to present to the hospital at a later stage of the disease, due to a reluctance to seek care early.36 Some studies have hypothesized that patients with EOPC may have a more aggressive tumor phenotype than patients with AOPC due to differences in their molecular profiles.37,38
Several studies have compared the molecular profiles of EOPC and AOPC, with mixed results. Bergmann et al.37 investigated the molecular characteristics of 7 patients with PDAC aged ≤ 40 years old, and found that all of the patients exhibited SMAD4 inactivation, which was associated with more aggressive tumors. Surprisingly, they also found that most patients had wild-type KRAS, which is unusual, as KRAS mutations are commonly found in patients with PDAC (90%).16 Wild-type KRAS was also associated with other targetable alterations, such as mismatch repair deficiency.38 In a recent preprint, Ogobuiro et al.39 showed that patients with EOPC with wild-type KRAS tumors had fewer TP53 mutations. Instead, carcinogenesis in EOPC is more likely driven by NRG1 and MET fusions. BRAF fusion was observed only in patients with AOPC with wild-type KRAS. In a subgroup analysis of patients with wild-type KRAS, the patients with EOPC had a better prognosis than those with AOPC; however, there was no difference in the survival of any patients with mutant KRAS. These molecular characteristics might explain the different results of prognostic studies comparing patients with EOPC and those with AOPC. Other studies have also shown a higher rate of mutations in several genes in patients with EOPC compared to patients with AOPC, such as CDKN2A, FOXC2, and PI3KCA.40,41
Whether younger patients had a higher prevalence of pathogenic germline variants (PGVs) than older patients remains unclear. Bannon et al.42 found that patients with EOPC had a higher prevalence of PGVs (most commonly BRCA1/2 and MMR) than patients with AOPC, which was especially true for patients < 42 years old (OR = 4.17; 95% CI, 1.42–11.84; P= 0.011). Castet et al.19 found that 22% of patients from the EOPC group and 13% from the AOPC group had PGVs, the most common of which was BRCA2. However, TP53, PMS2, and MSH6 PGVs were only found in the EOPC group. Additionally, patients with PGVs had a better OS than those without PGVs, independent of other factors. In contrast, Raffene et al.43 found no significant molecular profile differences between the EOPC and AOPC. It is possible that only a certain subset of EOPC patients have distinct molecular profiles than AOPC patients. Intra-tumoral (variability across individual cell populations within a biopsy site) and inter-tumoral heterogeneity (variability across individual cell populations between the primary and the metastatic site) may also be present, which are important confounders in genomic studies.41
Despite showing that patients with EOPC had a higher rate of distant metastasis, the results of the present meta-analysis also showed that patients with EOPC received more treatments than those with AOPC, which might explain why patients with EOPC had longer survival times than those with AOPC, even though they were more often diagnosed at a more advanced stage. This hypothesis was corroborated by a subgroup analysis of patients who underwent surgery, the results of which showed no significant difference in survival between the two groups. This phenomenon has been universally observed in other studies. Saadat et al.6 studied the differences in treatment utilization patterns between patients with EOPC and those with AOPC in the United States. They found that overall, patients with EOPC received more multimodal treatment regimens than those with AOPC, regardless of the cancer stage; therefore, they hypothesized that younger patients would be more willing to seek care, more likely to have private health insurance, have better access to tertiary healthcare centers, and be more fit to undergo treatment. Clinicians were also more willing to prescribe intensive treatments to younger patients because of their longer life expectancies compared to older patients; however, a high percentage of patients with EOPC and AOPC (19% and 39%, respectively) did not receive any treatment. Those who received no treatment tended to be non-White females with no private health insurance, less income, and lower levels of education, suggesting the vital role of the social determinants in the health of patients with PDAC. It is also important to note that most of these studies were conducted in developed countries, whereas patients with EOPC in developing countries may face more barriers to treatment, primarily due to financial hurdles. Younger patients with cancer may have no or inadequate health insurance coverage, limited financial assets, and significant work interruptions, leading to high financial strain.44 Therefore, patients with EOPC in developing countries may have different treatment utilization patterns than those in developed countries.
The present study has several limitations. First, we only included studies written in English, which may have increased publication bias. Second, there was also substantial heterogeneity between the included studies, possibly due to differences in the age cutoffs for EOPC, study time frames that might have lead to different treatment protocols, and the inclusion of covariates in the survival analysis. Therefore, we performed several sensitivity analyses that yielded similar conclusions. Third, the retrospective design of the included studies also means that some data, such as the specific chemotherapeutic agents used and genetic data, may be difficult to obtain. The present study does, however, have several strengths. First, to the best of the authors’ knowledge, this is the first meta-analysis to compare the survival of patients with EOPC to those with AOPC. Finally, we used multiple statistical methods21,27 to estimate the aHR of several studies to maximize study inclusion and minimize publication bias.
Figshare: Supplementary Tables and Figures. https://doi.org/10.6084/m9.figshare.26130982 45
Data is available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).
Figshare: PRISMA checklist and flowchart for ‘The Association between Early-Onset Pancreatic Ductal Adenocarcinoma and Patient’s Survival: A Systematic Review and Meta-Analysis’. https://doi.org/10.6084/m9.figshare.26548492 46
Data is available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).
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Are the rationale for, and objectives of, the Systematic Review clearly stated?
Yes
Are sufficient details of the methods and analysis provided to allow replication by others?
Yes
Is the statistical analysis and its interpretation appropriate?
I cannot comment. A qualified statistician is required.
Are the conclusions drawn adequately supported by the results presented in the review?
Yes
If this is a Living Systematic Review, is the ‘living’ method appropriate and is the search schedule clearly defined and justified? (‘Living Systematic Review’ or a variation of this term should be included in the title.)
Not applicable
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: gastroenterology; pancreatology; pancreatic cancer; liquid biopsy; meta-analysis
Are the rationale for, and objectives of, the Systematic Review clearly stated?
Yes
Are sufficient details of the methods and analysis provided to allow replication by others?
Yes
Is the statistical analysis and its interpretation appropriate?
Yes
Are the conclusions drawn adequately supported by the results presented in the review?
Yes
If this is a Living Systematic Review, is the ‘living’ method appropriate and is the search schedule clearly defined and justified? (‘Living Systematic Review’ or a variation of this term should be included in the title.)
Not applicable
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: surgical oncology
Alongside their report, reviewers assign a status to the article:
Invited Reviewers | ||
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Version 1 28 Aug 24 |
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