Testicular Seminoma: An Overview

A Cancer That Arises From Testicular Germ Cells

Seminoma is a highly-curable type of cancer that most often occurs in the testicles of males but can also affect other parts of the male body as well, such as the brain, chest, or abdomen. A painless lump or swelling within the testicle is usually the first sign of a seminoma.

Seminomas originate in the germ cells of males. Germ cells are reproductive cells that form into sperm cells and testicles in males and egg cells and ovaries in females.

This article explores the types, symptoms, causes, diagnosis, and treatment of this potentially serious yet slow-growing form of testicular cancer.

Testicular Cancer Diagnosis
Verywell / Joshua Seong

Types of Seminomas

Seminomas are one of several different types of testicular cancer. They fall under the broader category of germ cell tumors (GCTs) which account for 90% of testicular cancer cases.

There are two different types of GCT: seminomas, which are typically the more slow-growing form, and non-seminomas, which tend to be more aggressive.

Seminomas are further broken down into two subtypes:

  • Classic seminoma: The most common subtype that usually affects males between the ages of 25 and 45
  • Spermatocytic seminoma: A rare form that accounts for only around 5% of all seminomas and tends to affect males around the age of 65

Spermatocytic seminomas tend to grow more slowly and are less likely to metastasize (spread to other parts of the body) than classic seminomas.

Symptoms

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

Other symptoms may include:

  • A feeling of heaviness in the scrotum
  • Pain or discomfort in a testicle or the scrotum
  • A dull ache in the abdomen or groin
  • The build-up of fluid in the scrotum
  • Breast tenderness and growth (due to the secretion of the hormone estrogen by the tumor)
  • Lower back pain (if the tumor has spread to nearby lymph nodes)

It's important to keep in mind that a seminoma may cause no symptoms. Instead, the cancer may only be discovered during a routine physical exam or fertility assessment.

The vast majority of seminomas are confined to the testicles. Very rarely, a seminoma may originate in other areas of the body, such as the chest area (mediastinum) or the back of the abdominal cavity (retroperitoneum).

Causes

As with all cancers, it is not entirely clear why germ cell tumors occur in some males. Germ cells are sperm cells and egg cells that come together to form an embryo in a female's womb. Later in development, germ cells in males are supposed to mature into sperm-producing cells within the testicles.

If the germ cells don't mature as they are supposed to, they can sometimes change and multiply uncontrollably to form a seminoma or non-seminoma.

There are certain factors that increase the odds of developing testicular cancer. One such risk factor is a congenital condition known as cryptorchidism (an undescended testicle).

Cryptorchidism occurs in 2% to 5% of male children and, according to research, increases the risk of testicular cancer by nearly four-fold compared to males with normal testicles.

Other potential risk factors include:

Diagnosis

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, your healthcare provider will recommend surgery to remove the testicle and the tumor to check for cancer cells.

History and Physical Exam

A medical history may reveal a painless testicular lump or swelling. On physical examination, the healthcare provider will feel each testicle for a mass, swelling, or tenderness. They will also examine other parts of the body, such as the abdomen and inguinal lymph nodes of the groin.

Blood Tests

Blood tests that look for elevated levels of proteins—called tumor markers—are often ordered to aid in the diagnostic process. The same tests can also help stage the tumor (classify its severity).

One tumor marker that is sometimes raised with seminomas is beta-human chorionic gonadotropin (beta-hCG). Around 30% of people with testicular seminoma will have mild increases in beta-hCG.

Similarly, around 40% to 60% of people with a testicular germ cell tumor will have increases in lactate dehydrogenase (LDH).

Another tumor marker, called alpha-fetoprotein (AFP), would only be increased with a mixed tumor (meaning a tumor with seminoma and other types of testicular cancer). Pure seminomas do not produce AFP.

Imaging Tests

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

The first test is usually an ultrasound of the testicle, which uses reflected sound waves to visualize any growths in the testicles. This is often followed by computed tomography (CT) scan, which uses a series of X-ray images to check for the possible spread of cancer in the abdomen, pelvis, and possibly the chest.

Surgery

While all of the above-listed tests may be strongly suggestive of testicular cancer, the only way to definitively diagnose a seminoma is to obtain a tissue sample.

To do so, both the tumor and testicle need to be removed during a surgery known as a radical inguinal orchiectomy. A biopsy (a procedure used to obtain tissue samples) is rarely performed for testicular cancer as it may lead to the spread of cancer.

After the testicle and tumor are removed, they are sent to the lab for evaluation by a specialist known as a medical pathologist. The findings from the gross (visual) and histological (microscopic) evaluation will help guide the treatment plan.

Treatment

The treatment for a seminoma involves surgery and sometimes radiation or chemotherapy. The treatment plan varies by whether the cancer is stage 1 (localized), stage 2 (regional), or stage 3 (metastasized..

Surgery

The surgical removal of the testicle is the primary treatment of a seminoma.

For those with stage 1 seminomas, surgery is usually curative on its own. After surgery, most people only require ongoing monitoring by a cancer specialist, called an oncologist, to check for the possible recurrence of cancer. The monitoring may be recommended for up to 10 years.

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

Radiation and Chemotherapy

Radiation is sometimes used after surgery to kill any remaining cancer cells in the retroperitoneal lymph nodes. This is especially true for people with stage 2 seminoma, in whom surgery and radiation can afford high cure rates. Radiation may also be used to treat stage 3 seminomas that have spread to distant organs in the body, such as the brain.

For stage 3 testicular cancer, chemotherapy may be used in place of radiation for those whose cancer has spread to nearby lymph nodes or to distant organs.

Even though stage 3 seminomas have spread to other parts of the body by the time they are found, most can still be cured with radical inguinal orchiectomy, followed by chemotherapy.

Prevention

There are currently no recommendations for the screening for testicular cancer. This includes both testicular examinations performed by a healthcare professional and testicular self-exams.

For its part, 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, those with certain risk factors (such as cryptorchidism or a family history of testicular cancer) should talk with their healthcare provider about the need for ongoing monitoring or monthly testicular self-exams.

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 male's ability to have sex.

Moreover, if you are concerned about the cosmetic implication of losing a testicle, know that some males 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 advanced stages), undergoing treatment for it can be a physically and emotionally taxing process.

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

Frequently Asked Questions

  • What type of cancer is seminoma?

    A seminoma is a form of testicular cancer known as a germ cell tumor (GCT). Germ cells in males are those that develop into sperm cells or testicles. In some people, the germ cells in testicles do not mature as they are supposed to but rather change and multiply to form seminomas.

  • Is seminoma cancer curable?

    Yes. Around 70% of people with stage 1 testicular seminoma can be cured using surgery alone. Many cases of stage 2 testicular seminomas can also be cured with a combination of surgery and radiation (and, in rare cases, chemotherapy).

  • What percentage of testicular cancer is seminoma?

    Seminomas belong to a group of testicular cancers known as germ cell tumors (GCTs) that account for 90% of all testicular cancer cases. Seminomas themselves account for between 40% and 50% of all testicular cancer cases.

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