What is thymoma?
This cancer develops in the outer surface of the thymus, a gland behind the breastbone that produces T-cells, a type of white blood cells. Thymoma is rare, but it is the most common tumor in adults affecting the mediastinum, which is the cavity between the lungs containing the heart, esophagus, and trachea.1 A tumor of the thymus tends to grow slowly and rarely spreads to other parts of the body. However, of the estimated 400 Americans who develop this cancer each year, half are diagnosed with metastatic thymoma.2 When the cancer metastasizes, only 45% of patients survive five years after their diagnosis. Additional information on thymoma.
TCGA's study of thymoma was part of an effort to characterize rare tumor types.
What have TCGA researchers learned about thymoma?
- Four major subtypes were defined from multi-omic data on 117 samples:
- The subtypes correspond to known hisopathological subtypes B, TC, AB, and a mix of A and AB.
- The subtypes are associated with differential survival.
- Thymomas have among the lowested mutational burden among all adult cancers.
- Enrichment of HRAS, NRAS, TP53, and recurrent GTF2I mutations were observed.
- Expression of autoimmune targets and aneuploidy links thymoma to myasthenia gravis.
- A specific mutation within GTF2I occurred only in thymoma of all TCGA samples and may present a potential drug target.