Testicular Cancer: Classifications

Germ Cell Tumors (GCTs) Nearly all testicular cancers occur in the germ cells responsible for making sperm (in this instance germ means “seed”). Germ cells give rise to two main kinds of cancer, seminomas and nonseminomatous tumors.

Seminomas are the most common germ cell type of testis cancers. They occur most often in men between the ages of 20 and 45 years old. Seminomas are usually treated surgically, sometimes with the addition of radiation. Seminomas that have spread throughout the body are treated with chemotherapy.

Nonseminomatous germ cell tumors may be more aggressive and are treated somewhat differently from seminomas. These tumors also occur in men in their 20s and 30s. The histologic types are:

  • Embryonal carcinoma
  • Yolk sac carcinoma
  • Choriocarcinoma
  • Teratoma

Carcinoma in situ (CIS) is a non-invasive form of germ cell cancer that hasn’t spread beyond the tubes in the testicles where sperm cells are formed. Because CIS doesn’t always turn into an invasive cancer sometimes the best option is to “watch and wait.”

Stromal Cell Tumors A small percent of testicular cancers develop in the stromal cells, the supportive tissues of the testicles that produce the male hormone, testosterone. However these tumors are generally benign.

Stromal tumors account for fewer than 1 in 20 adult testicular tumors but up to 1 in 5 testicular tumors in boys. There are two types:

  • Leydig cell tumors
  • Sertoli cell tumors

Stromal cell tumors generally do not spread beyond the testicle and can usually be cured by surgery.

A tumor in the testicles can also be “secondary”—that is, the result of a cancer elsewhere in the body. Lymphoma is the cancer that most commonly spreads to the testicles. Boys with acute leukemia may develop testicular tumors and so may men with cancers of the prostate, lungs, skin, and kidneys. Cancers are generally named for their point of origin. Tumors that rise in other organs are not called testicular cancers.