If you have testicular cancer, your doctor will want to find out what type it is. Knowing the type helps your doctor decide the best way to treat it.
More than 90 percent of testicular cancers begin in a type of cell in the testicles called a germ cell. These are the cells that give rise to sperm. There are two main types of germ cell tumors: seminomas and nonseminomas. These two types have been found to occur almost equally.
About 10 percent of testicular cancers do not begin in germ cells. These types are much less common. They are called stromal tumors.
Secondary testicular tumors are tumors that start in other parts of the body and then spread to the testicles.
Cancer in the cells that make sperm, called germ cells, is called seminoma. Seminomas tend to grow slowly and often respond very well to treatment.
There are two types of seminomas. These are called typical (classical) and spermatocytic seminomas. More than 90 percent of seminomas are typical. Typical seminomas are usually found in men between the ages of 25 and 45. Spermatocytic seminomas tend to occur later in life. The average age of diagnosis is 65.
Cancer that grows in the embryonic germ cells is called nonseminoma. Nonseminomas grow faster than seminomas. They are slightly less common than seminomas and occur in men between their late teens and early 30s. They tend to spread to lymph nodes in the abdomen and to other parts of the body.
These are the subtypes of nonseminomas:
Embryonal carcinomas. This type of nonseminoma tends to grow and spread quickly. Under a microscope, these tumors look similar to tissue in early embryos.
Yolk sac carcinomas. This is the most common form of germ cell tumor in infants and boys. These are usually treated successfully when found in children. They can be harder to treat in adults.
Choriocarcinomas. This type of nonseminoma is very rare and tends to be aggressive. It often spreads quickly to other parts of the body.
Teratomas. Under a microscope these tumors look like the three layers of tissue in a growing embryo. They are rarely the only type of cell present.
The stroma are tissues in the testicles that make hormones. Stromal tumors start in these tissues. There are two main kinds of stromal tumors: Leydig cell tumors and Sertoli cell tumors. Overall, stromal cell tumors make up less than 5 percent of all adult cases of testicular cancer, but up to 20 percent of all childhood cases.
Secondary tumors are tumors that start in another part of your body and spread to your testicles. For example, lymphoma, a kind of cancer of the lymph nodes, can spread to the testicles. In men age 50 and older, secondary testicular cancer that begins as lymphoma is more common than tumors that start in the testicles. The most common secondary testicular cancer is lymphoma. Other cancers that may spread to your testicles include lung, melanoma, kidney, and prostate cancer.