An Overview of Seminoma

A Cancer That Arises From Testicular Germ Cells

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Seminoma is a type of highly-curable cancer that originates in the germ cells of the testicle. A painless lump or swelling within the male testicle is usually the first sign of this cancer.

Diagnosing seminoma is a multi-step process that entails a medical history, physical examination, testicular ultrasound, and blood tests to check for tumor markers.

If testicular cancer is suspected based on these test results, a doctor will recommend surgery to remove the testicle and the tumor. The testicle can then be examined under a microscope for cancer cells (and the type of cancer—such as a seminoma—can be confirmed).

While surgery is the primary treatment for seminoma, a person may undergo radiation or chemotherapy for cancer that has spread to the lymph nodes or distant organs.

Keep in Mind

The vast majority of seminomas occur in the testicle. Very rarely, a seminoma may develop in other areas of the body, such as the mediastinum (chest area) or the retroperitoneum (abdominal area).

Types and Symptoms

There are two main sub-types of testicular seminomas—classical and spermatocytic seminomas.

Classic seminoma is by far the most common sub-type and usually occurs in men between the ages of 25 and 45 years.

Spermatocytic seminoma comprises only around 5% of all seminomas and tends to develop in older men (around 50 years).

Spermatocytic seminomas grow more slowly and are less likely to spread than classic seminoma.

The most typical symptom of a seminoma is the finding of a painless lump, mass, nodule, or swelling on one testicle.

Other symptoms may include:

  • A feeling of heaviness or dull achiness in the scrotum or lower abdomen
  • Breast tenderness and growth (due to a hormone secreted by the tumor)
  • Back pain, if the cancer has spread (called metastasis) to nearby lymph nodes
  • Cough or hemoptysis, if the cancer has spread to the lungs
  • Headache, if the cancer has spread to the brain

It's important to keep in mind that a seminoma may cause no symptoms. Instead, the cancer may be discovered incidentally during a routine physical examination or during a workup for infertility.

Causes

A seminoma arises from germ cells that grow uncontrollably.

Germ cells are the cells that form an embryo in a mother's womb. Later on in development, germ cells are supposed to mature into sperm-producing cells within the male testicles.

Testicles are egg-shaped organs contained within a loose sac of skin called the scrotum, which lies below a man's penis. Testicles have two main functions—they make the primary male hormone testosterone, and they make sperm.

If germ cells remain immature within the testicle, they can eventually grow uncontrollably to form a seminoma or another type of testicular cancer called a non-seminoma.

While seminomas and non-seminomas both occur at about the same rate, seminomas grow and spread more slowly than non-seminomas.

There are certain factors that increase a male's chances of developing a seminoma.

One classic risk factor is a congenital condition called cryptorchidism, in which one or both testicles does not descend into the scrotum before birth.

This condition occurs in about 2 to 5% of boys at term. According to research, there is approximately a 3.6 fold increased risk for testicular cancer after cryptorchidism.

Other potential risk factors include:

  • Personal history of testicular cancer
  • Family history of testicular cancer
  • Down syndrome
  • Tall stature
  • Male infertility
  • Being born with an abnormal chromosomal pattern (a 46XY, 45XO karyotype)
  • Certain birth factors (e.g., low birth weight)
  • Caucasian race

Diagnosis

In order to diagnose seminoma, a doctor will first take a medical history and perform a physical examination.

History and Physical Exam

A medical history may reveal symptoms like a painless testicular lump or swelling.

On physical exam, a doctor will feel each testicle for a mass, swelling, or tenderness. He will also examine other parts of the body, especially the abdomen and lymph nodes.

Blood Tests

Blood tests that look for elevated levels of proteins (called tumor markers) are often ordered to aid in the diagnostic process (as well as eventually in staging and monitoring the cancer).

One tumor marker that is raised by some seminomas is beta-human chorionic gonadotropin (beta-hCG).

About 30% of patients with testicular seminoma have mild increases of hCG.

Another tumor marker of testicular cancer is called alpha-fetoprotein (AFP). Pure seminomas do not produce AFP. However, some germ cell tumors are mixed, meaning they have both seminoma and non-seminoma areas. These tumors may produce both beta-hCG and AFP.

Lastly, there is lactate dehydrogenase (LDH). About 40 to 60% of people with a testicular germ cell tumor (either seminoma or non-seminoma) have increased levels of this protein.

Imaging Tests

Following the history, physical exam, and blood tests for tumor markers, imaging tests will be performed.

The first test is usually an ultrasound of the testicle to visualize the tumor, followed eventually by a computed tomography (CT) scan of the abdomen and pelvis to stage the cancer.

Other imaging tests may be ordered if a doctor suspects that the cancer has spread to other organs. For instance, a chest X-ray may be ordered to check for the spread of the cancer to the lungs.

Positron emission tomography (PET) scanning is not often used to diagnose a seminoma, but may be used to track the tumor's size, after a person undergoes treatment.

Surgery

While all of the above tests (especially the ultrasound) point towards a diagnosis of testicular cancer, the only way to confirm a seminoma is to obtain a tissue sample.

Unfortunately, a biopsy (when a small sample of the abnormal mass in the testicle is removed and examined under a microscope for cancer cells) is rarely performed for testicular cancer, due to the concern for cancer spread.

So to confirm a seminoma diagnosis, a person usually undergoes a surgery called a radical inguinal orchiectomy. During this surgery, the entire testicle (the one containing the tumor) is removed and then examined under the microscope by a doctor called a pathologist.

After looking closely at the cancer cells, the pathologist can relay the findings (e.g., the type of cancer and the extent) to the patient and the cancer care team. These findings will help guide a patient's treatment plan.

Treatment

The treatment for a seminoma involves surgery and sometimes radiation or chemotherapy.

Surgery

Surgical removal of the testicle is the primary treatment of a seminoma.

For those with stage I seminomas, surgery is usually curative. After surgery, most patients can be followed by active surveillance, which means close monitoring for up to 10 years (e.g., getting physical exams, imaging tests, and blood tests every few months, to start).

Depending on the type and extent of the cancer, your surgeon may also remove certain lymph nodes within the back of the abdomen and around major blood vessels, where the cancer may have spread. This complex surgical procedure is called a retroperitoneal lymph node dissection.

Since this type of lymph node dissection can result in short-term complications, such as infection, bowel blockage, or loss of the ability to ejaculate, it is performed sparingly now in the United States.

Radiation

Radiation is sometimes used after surgery to kill any remaining cancer cells in the retroperitoneal lymph nodes. It may also be used to treat seminomas that have spread to distant organs in the body, such as the brain.

Chemotherapy

Instead of radiation, chemotherapy may be given to those whose cancer has spread to nearby lymph nodes or to distant organs.

Prevention

There are currently no professional recommendations about screening for testicular cancer, and this includes both testicular examinations performed by health care professionals and testicular self-exams.

That said, the American Cancer Society states that men should be aware of testicular cancer and see a doctor right away if they notice any lump in a testicle.

In addition, the American Cancer Society recommends that men with certain risk factors (for example, cryptorchidism, a history of testicular cancer, or a family history of testicular cancer) talk with their doctor and consider monthly testicular self-examinations.

Coping

If you have been diagnosed with testicular cancer and are undergoing surgery, you may be worried about the aftermath. Rest assured though—losing one testicle does not generally cause a significant decrease in testosterone and therefore, does not usually affect a man's ability to have sex.

Moreover, if you are concerned about the cosmetic implication of losing a testicle, know that some men do undergo reconstructive surgery to obtain a prosthetic testicle.

A Word From Verywell

While testicular cancer is one of the most curable cancers (even when diagnosed at an advanced stage), undergoing treatment for it can be a physically and emotionally grueling process.

If you have been diagnosed with a seminoma or other type of testicular cancer, please reach out to your friends, family, and cancer care team for support. You do not have to go through this alone.

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