Testicular cancers are malignancies that develop in one or both of the testicles. The testicles (or testes) are two egg-shaped glands of the male reproductive system that sit outside of the body in a skin sac called the scrotum. 

The testicles are responsible for the production and storage of sperm, the male gamete (reproductive cell) that swims to fertilise the female gamete, called ova or eggs.  They are also responsible for producing and secreting testosterone, the primary male hormone. Testosterone is responsible for the regulation of sexual development (including development of male reproductive organs, and secondary sex characteristics such as facial hair and voice deepening), bone and muscle mass, fat distribution, sex drive (or libido), sperm production and red blood cell production. 

Testicular cancers are generally diagnosed in men between the ages of 25-40, however, it can affect anyone with testicles – including men, teenagers, transgender women, non-binary individuals, and intersex people – at any age.

Types of Testicular Cancers

There are several types of testicular cancers, which are categorised by the types of cells they develop from. 

Seminoma – Germ Cell Tumours

Seminomas are one of the most common forms of testicular cancers. They develop from germ cells, which are the biological cells that develop into gametes during fetal development. In general, seminomas develop between the ages of 25-45, and are slow growing, rarely metastasise, and usually have a good prognosis.  

In some cases, seminomas can increase levels of human chorionic gonadotropin (HCG), which is a hormone produced by the placenta (an organ that develops alongside a fetus during pregnancy) during early stages of pregnancy. In men, this hormone acts similarly to the luteinising hormone (LH), which is responsible for regulating sperm production and signalling for the production of testosterone. Excess levels of these hormones can cause a variety of side effects, including fertility issues. 

Non-Seminoma – Germ Cell Tumours

Non-seminoma germ-cell tumours are also a common form of testicular cancer. They often develop between their late teens and early 20’s, and often develop and metastasise more quickly than seminomas. There are four primary types of non-seminoma germ-cell tumours.

Embryonal Carcinomas 

Embryonal carcinomas are a common type of testicular tumours that often develop from primordial germ cells, which are germ cells that have not yet developed into gametes. While this type of tumour can be aggressive, it often has a good prognosis. 

In some cases, embryonal carcinomas can increase levels of alpha-fetoprotein (AFP), which is responsible for transporting heavy metal ions in fetal blood during early stages of pregnancy, and HCG in the blood.

Choriocarcinomas

Choriocarcinomas are rare and aggressive tumours that often develop from trophoblastic cells, which are specialised cells in the placenta. It is often fast growing, has a high metastasis rate, and may be a part of a mixed germ-cell tumour. While they are aggressive, they may have a good prognosis when caught early.
In most cases, testicular choriocarcinomas increases the levels of HCG in the blood.

Endodermal Sinus Tumours 

Endodermal sinus tumours, or yolk sac tumours, are the most common form of testicular cancer in children. These types of tumours develop in the lining of the yolk sac of an embryo, and often increase levels of AFP in the blood. While this type of tumour is highly aggressive, they can have a good prognosis. 

Teratomas

A teratoma is a rare type of germ-cell tumour that contains bodily tissue, such as hair, bone, muscle and teeth. They usually are non-functional (do not secrete hormones), and may be seen as part of a mixed germ-cell tumour. While it is often aggressive, it can have a good prognosis when caught early.

Teratomas can be classified based on how the cells look under the microscope:

• Mature teratoma: cells look similar to healthy tissue but contain bodily tissue that shouldn’t be present within the brain (such as skin, hair, muscle, bone, etc.). These tumours are generally benign (non-cancerous). 
• Immature teratoma: cells look similar to those found in a foetus, and also have components not generally found in the brain. These tumours are generally malignant (cancerous), but can have a good prognosis when found early. 
• Teratoma with malignant transformation: a malignant GCT transforms into a malignant non-germ cell tumour, also known as a somatic (all cells that are not germ cells) malignancy. These tumours are highly aggressive, and may not have as good of a prognosis as other GCTs. 

Mixed Germ Cell Tumours 

Mixed germ-cell tumours are cancers that develop from a variety of different cancerous cells. These cells can be a mix of seminoma and non-seminoma tumour cells, or cells from various non-seminoma tumours. When a mixed germ-cell tumour is found, they are often treated similarly to non-seminoma tumours due to their similar growth and metastasis rates. 

Stromal Tumours 

Stromal tumours are cancers that originate from the supportive hormone-producing tissues of the testicles, called the stroma. They are very rare, and develop from Sertoli and Leydig cells, which are support cells in the male reproductive system. 

Sertoli-Leydig cell tumours are cancers that produces male hormones, such as testosterone. These types of tumours are often benign (non-cancerous) and slow growing, however, in rare instances they can be cancerous. Malignant (cancerous) Sertoli-Leydig cell tumours usually don’t respond well to chemotherapy and radiation therapy, and may have a poorer prognosis than other testicular cancers. 

Intratubular Germ Cell Neoplasias (ITGCNs)

Intratubular germ-cell neoplasias (ITGCNs) is a condition where cells in the testicles look abnormal, but they haven’t spread beyond their point of origin. While this condition is not a malignancy, there is a high risk that it can transform into a form of testicular cancer. ITGCN is considered rare, and is often difficult to diagnose.

Treatment

If testicular cancer is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.

Cancers can be staged using the TNM staging system:

• T (tumour) indicates the size and depth of the tumour.
• N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
• M (metastasis) indicates whether the cancer has spread to other parts of the body.

This system can also be used in combination with a numerical value, from stage 0-IV:

• Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
• Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
• Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
• Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
• Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
  

Cancers can also be graded based on the rate of growth and how likely they are to spread:

• Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
• Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour. 
• Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour. 

Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you. 

Treatment is dependent on several factors, including location, stage of disease and overall health.

Treatment options for testicular cancer may include:

• Surgery, potentially including:
  • Orchidectomy/orchiectomy (removal of one (unilateral) or both (bilateral) testicles).
  • Lymphadenectomy (removal of affected lymph nodes).
  • Testicular prosthetic surgery (insertion of a prosthetic testicle(s) after an orchidectomy).
• Radiation therapy.
• Chemotherapy.
• Watch and wait (for early-stage testicular cancers or after an orchidectomy).
• Clinical trials.
• Palliative care.

For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page. 

Testicular Cancer Treatment and Fertility

Treatment for testicular cancer may make it difficult to conceive a child. If fertility is important to you, discuss your options with your doctor and a fertility specialist prior to the commencement of treatment. 

Risk factors

While the cause of testicular cancer remains unknown, the following factors may increase the risk of developing the disease:

• Having a personal history of testicular cancer.
• Having a family history of testicular cancer.
• Being infertile.
• Having certain conditions, such as
  • Human immunodeficiency virus (HIV).
  • Acquired immunodeficiency syndrome (AIDS).
  • Cryptorchidism (undescended testicle(s)).
  • Hypospadias (penile abnormality).
  • Inguinal hernia (lump in the groin – repaired or not repaired). 

Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.

Early symptoms

In some cases, testicular cancers appear asymptomatic.

Common symptoms of testicular cancer may include:

• A painless swelling in the testicle(s).
• A lump in the testicle(s). 
• Changes in testicular size and/or shape. 
• A feeling of heaviness in the scrotum.
• A feeling of unevenness in the scrotum. 
• Pain or discomfort in the testicle(s) and/or scrotum.
• Fluid build-up in the scrotum.
• Aches in the lower abdomen, testicle(s) and/or scrotum. 
• Back pain.
• Enlargement and/or tenderness of breast tissue caused by excess hormones.

Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.

Diagnosis/diagnosing

If your doctor suspects you have testicular cancer, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.  

Physical examination 

Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.  More specifically, they will examine the testicles and scrotum and determine if there are any lumps or swelling present.

Imaging 

The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-ray and/or ultrasound, depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. 

Blood tests

Blood tests are used to assess overall health and detect any abnormalities. Some of these tests may include:

• General blood test to assess overall health.
• Full blood count, which measures the levels of red blood cells, white blood cells and platelets.
• Testing for tumour markers, potentially including:
  • Alpha-fetoprotein (AFP).
  • Beta human chorionic gonadotropin (beta-hCG).
  • Lactate dehydrogenase (LDH).

Exploratory Surgery

After conducting the previously mentioned diagnostic tests, your doctor may strongly suspect that you have a testicular cancer. In most cases, a diagnosis can be confirmed after a biopsy, where a section of tissue is removed and analysed for cancer cells. However, doctors avoid conducting a biopsy in patients who have suspected testicular cancer as there is a small risk that making an incision in the scrotum could cause cancer cells to spread.  As such, the only way to confirm the diagnosis safely is to perform a unilateral orchidectomy (removal of one testicle). 

Once the testicle has been removed, it will be sent to a laboratory and analysed for cancer cells.

Prognosis (Certain factors affect the prognosis and treatment options)

While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage testicular cancers have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.  

References

• American Cancer Society
• Cancer Australia
• Cancer Council Australia

^{Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.}