Testicular Cancer Types: Seminoma, Nonseminoma, and More

Seminomas and nonseminomas make up most cases of testicular cancer, but there are other rare types. The differences between types can affect how quickly they spread and how doctors treat them.

Testicular cancer, when cancer originates in the testicles, can take several forms, depending on what types of cells become cancerous.

The National Cancer Institute reports that about 95% of all testicular cancer cases start in the germ cells and are called germinal tumors. The two main types of germinal tumors are seminomas and nonseminomas.

Stromal tumors form in different cells and are much less common than germinal tumors.

Cancer can also begin elsewhere in the body but spread to the testicles.

Seminomas

Seminomas are one of the two main types of germ cell testicular cancers. Germ cells are the reproductive cells that produce sperm in males and eggs in females.

Seminoma treatment usually involves surgery to remove the testicles (orchiectomy) as well as chemotherapy, radiation therapy, or both.

If treated before the cancer has had a chance to metastasize (spread), the 5-year relative survival rate is about 99%.

There are two subtypes of seminomas.

Classical seminomas account for more than 95% of seminomas and tend to occur in younger males.

Spermatocytic seminomas are much less common and usually affect older males. They grow more slowly than classic seminomas and are less likely to spread.

Nonseminomas

Nonseminomas tend to grow and spread more quickly than seminomas, so it’s essential to get an accurate diagnosis and start treatment as soon as possible. Treatment options for nonseminomas are generally the same as those for seminomas.

There are four subtypes of nonseminomas, though these tumors often have a mix of subtypes. Those subtypes include:

• choriocarcinoma, a fast-growing type of testicular cancer that tends to spread to the lungs, bones, and brain
• embryonal carcinoma, which is found in about 40% of testicular tumors
• teratoma, which has three subtypes: mature, immature, and teratomas with somatic type malignancy
• yolk sac carcinoma, the most common type of testicular cancer found in children and so named because it resembles the yolk sac of a human embryo

Carcinomas in situ

Carcinoma in situ, aka intratubular germ cell neoplasia, refers to noninvasive precancerous testicular germ cells. These cells look like typical cells under a microscope, but a biopsy can sometimes identify them. This often occurs incidentally, such as for a fertility test.

Because carcinoma in situ doesn’t always become invasive, your doctor may recommend careful monitoring. This includes regular physical exams and screenings, such as ultrasounds and blood tests, to determine whether a malignant tumor has formed.

A 2019 study suggests that when a biopsy reveals carcinoma in situ, there is about a 50% chance it will develop into a malignant germ cell tumor.

Sex cord stromal tumors

The stroma is the hormone-producing tissue in the testicles. The sex cords are structures in human embryos that help determine whether the embryo will become male or female.

Sex cord stromal tumors (SCSTs) originate in the cells of these regions.

Testicular SCSTs account for only about 5% of testicular tumors overall, but they’re the second most common type in children, according to the International Ovarian and Testicular Stromal Tumor Registry.

Secondary testicular cancers

Secondary testicular cancers are not considered “true” testicular cancers because the tumors form in another part of the body and metastasize to the testicles. The most common type of cancer to affect the testicles is lymphoma, according to the American Cancer Society.

Other cancers that may spread to the testicles include:

• kidney cancer (and other cancers of the abdominal organs)
• leukemia
• lung cancer
• melanoma (skin cancer)

Frequently asked questions

What is the most aggressive form of testicular cancer?

Two of the most aggressive forms of testicular cancer are choriocarcinomas, which are rare, and embryonal carcinomas, which are much more common.

What is the least aggressive testicular cancer?

Spermatocytic tumors, which tend to develop in older males, are among the least aggressive testicular cancers. These tumors tend not to spread beyond the testicles.

But because these tumors are less aggressive, diagnosis often occurs after the tumors have been growing for a long time.

Which is worse — seminoma or nonseminoma?

Both seminomas and nonseminomas are treatable cancers, especially if diagnosed early. But nonseminomas are more aggressive and tend to affect males at a younger age compared with seminomas.

Takeaway

Regardless of the type of testicular cancer you have, it’s helpful to review your treatment options with an oncologist who specializes in treating this condition.

Though orchiectomy is usually required in most cases, the type and stage of your particular cancer, as well as your age and overall health, will affect your treatment plan.