Metastatic Malignant Thymoma to the Abdomen: A SEER Database Review and Assessment of Treatment Strategies.

Abstract

BackgroundThymoma is a neoplasm occurring in 0.15 of 100,000 persons/year. Abdominal metastases are rare. We report the incidence of malignant thymoma (MT) and suggest imaging and treatment options for cases of abdominal metastasis.MethodsA National Cancer Institute’s Surveillance, Epidemiology and End Results database review was conducted to identify MT cases, followed by a literature review examining cases of metastases to the abdomen. Incidence rates were calculated, and symptoms, treatments, size and location of tumors, disease-free interval (DFI), and survival time were recorded.ResultsFrom 1973 to 2008, a total of 1,588 MT cases were identified (45.4 cases/year), which were extrapolated to 2,724 over 60 years. Incidence has risen from 17 cases in 1973 to 90 cases in 2008, with a larger incidence in males than females (0.23 vs. 0.17 per 100,000). There were 25 cases of abdominal metastasis (0.92%), 13 of which were asymptomatic. There was a wide variety of DFI and survival noted amongst the case reports. Multiple treatment modalities were used.ConclusionsThe incidence of MT is on the rise with a male predominance. All patients should receive routine imaging to look for extrathoracic metastases as half will not have symptoms. All patients with abdominal metastases should be treated using a multimodal approach.