Table 4. Summary table of advantages and disadvantages of large-database studies.
| Database | Pros | Cons |
|---|---|---|
| All | Large series of patients | Retrospective studies contain bias; no detailed records of failure patterns, chemotherapy, and radiotherapy |
| SEER | Propensity score-matched studies were performed; cause of death and second malignancy were available; can be focused on specific histological type | Surgical margin status, comorbidities, patient performance status, and Masaoka-Koga staging were unavailable; WHO histology classification was unavailable for the majority; no central review of histological classification was performed; the ethnic characteristics were diverse |
| ChART | Propensity score-matched studies were performed; TNM staging was utilized | Missing patient information caused the majority to excluded from the analysis; Masaoka-Koga staging was unavailable |
| JART | The number of patients with missing data (including OS) was very small; Masaoka staging was utilized | No central review of histological classification was performed |
| ESTS | Clinico-pathological variables affecting long-term survival were investigated; Masaoka staging was utilized; neuroendocrine thymic tumors were excluded from the analysis | Only surgical cases in high-volume centers were included; no central review of histological classification was performed; nodal status and the site of distant metastases were unavailable |
| NCDB | Margin status was incorporated into the analysis | Masaoka-Koga staging was unavailable; no central review of histological classification was performed |
| BCCAR | Variability in clinical behavior and practice variations were focused; Masaoka-Koga staging was utilized; pathology review and reclassification were performed | 10% of the data were unavailable for analysis; the number of patients with stage I was limited |
| ITMIG | Completely resected stage II and III thymoma were the focus; Masaoka or Masaoka-Koga staging was utilized | Stages IIA, IIB, and II were all categorized as stage II. |
SEER, Surveillance, Epidemiology, and End Results database; WHO, World Health Organization; ChART, Chinese Alliance for Research of Thymoma database; JART, Japanese Association for Research on the Thymus Database; OS, overall survival; ESTS, European Society of Thoracic Surgeons database; NCDB, National Cancer Database; BCCAR, British Columbia Cancer Agency Registry; ITMIG, International Thymic Malignancies Interest Group Retrospective Database.