PURPOSE: To integrate the pathology and epidemiology of thymic neoplasms and demonstrate clinical outcomes identified in NCI SEER database population statistics.
METHODS: Data were obtained from NCI’ s SEER program and include information from Registry 17 (1973-2006) and Registry 9 (1973-2006). Cases were designated as thymoma, not othersie specified, or by (WHO) Types A, AB, B1, B2, B3, and C designations. Cases were compared by yearly trends, age-incidence plots, log-log transformations, age-frequency density, and relative Kaplan-Meier survival rates. Rates are expressed as number of cases per 100,000 persons.
RESULTS: Thymomas and thymic carcinomas are diseases of adults, and have increased, nearly identically, in incidence continuously over thirty-three years (1973-2006) with a near doubling in incident rate. Log-log plots of age versus incidence showed near-parallel slopes of thymic histologic types, suggesting a common pathogenesis for all thymomas. Frequency density plots showed that all thymomas (low grade, high grade, and carcinoma) have near-identical distributions. Relative Kaplan-Meier survival calculations demonstrated that 5-year survival rates can be stratified into three groups: I. Type A, AB, B1 (85%); II. Type B2, B3 (75%); and III Type C (54%). Survival is also directly dependent extent of regional tumor spread and dissemination.
CONCLUSION: Thymic tumors are increasing as the age of the population increases, although there may be other factors generating the increase in incidence. All thymomas have similar age frequency distributions despite the differences in tumor histologic patterns. Results of survival analysis suggest that a more limited stratification of tumor histologic patterns would best define prognostic groups. Except for survival, thymic carcinomas have the same epidemiologic patterns as other thymic tumors.
CLINICAL IMPLICATIONS: Thymomas and thymic carcinomas share several epidemiologic parameters and suggest a common carcinogenic pathway. The clinical outcome is dependent of extent of disease at presentation and tumor histologic grade/differentiation.
DISCLOSURE: Arnold Schwartz, No Financial Disclosure Information; No Product/Research Disclosure Information