TCGA's Study of Testicular Germ Cell Cancer
What is testicular germ cell cancer?
More than 90% of testicular cancer start in the germ cells, which are cells in the testicles and develop into sperm. This type of cancer is known as testicular germ cell cancer. Testicular germ cell cancer can be classified as either seminomas or nonseminomas, which may be identified by microscopy.1 Nonseminomas typically grow and spread more quickly than seminomas. A testicular germ cell tumor that contains a mix of both these subtypes is classified as a nonseminoma. TCGA studied both seminomas and nonseminomas.
Testicular germ cell cancer is rare, comprising 1-2% of all tumors in males.2 However, it is the most common cancer in men ages 15 to 35.2 The incidence of testicular germ cell cancer has been continuously rising in many countries, including Europe and the U.S.3 In 2013, about 8,000 American men were estimated to be diagnosed with the cancer.1 Of those, 370 are predicted to die from the disease.1 Men who are Caucasian, have an undescended testicle, abnormally developed testicles, or a family history of testicular cancer have a greater risk of developing testicular cancer. Fortunately, testicular germ cell cancer is highly treatable. Additional information on testicular cancer.
TCGA's study of testicular germ cell cancer was part of an effort to characterize rare tumor types.
What have TCGA researchers learned about testicular germ cell cancer?
- In a study of 137 testicular germ cell tumors (TGCTs), distinct molecular patterns characterized each of the major histological subtypes of the disease:
- embryonal carcinoma
- yolk sac
- All histology types exhibited extensive aneuploidy and low mutation frequency.
- Global DNA methylation and miRNA expression differ greatly between histology types, implicating a likely major role of epigenomic processes in determining histologic fates.
A subset of pure seminomas are defined by KIT mutations, distinct DNA methylation and immune infiltration profiles, and decreased KRAS copy number.
- Significant somatic mutations are present only in TGCTs with seminoma components.
- Certain molecular features may potentially be used as biomarkers for risk stratification.
1American Cancer Society. Cancer Facts and Figures 2012. Atlanta: American Cancer Society, Inc. 2012.
2 Segal R. Surveillance programs for stage I nonseminomatous germ cell tumors of the testis. Urol Oncol. 2006 Jan-Feb; 24(1):68-74.
3 Vasdev N, Moon A, Thorpe AC. Classification, epidemiology and therapies for testicular germ cell tumours. Int J Dev Biol. 2013; 57(2-4):133-139.