With timely diagnosis, testicular cancer is most likely treatable and most often curable. It is the most common cancer in men 15 to 34 years old.
Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. Cancer that starts in the testicles is called testicular cancer.
Germ cell tumours
More than 90% of cancers of the testicle develop in special cells known as germ cells. These are the cells that make sperm. The 2 main types of germ cell tumours (GCTs) in men are:
- Seminomas
- Non-seminomas, which are made up of embryonal carcinoma, yolk sac carcinoma, choriocarcinoma, and/or teratoma
Doctors can tell what type of testicular cancer you have by looking at the cells under a microscope.
These 2 types occur about equally. Many testicular cancers contain both seminoma and non-seminoma cells. These mixed germ cell tumours are treated as non-seminomas because they grow and spread like non-seminomas.
Stromal tumours
Tumours can also develop in the supportive and hormone-producing tissues, or stroma, of the testicles. These tumours are known as gonadal stromal tumours. They make up less than 5% of adult testicular tumours but up to 20% of childhood testicular tumours. The 2 main types are Leydig cell tumours and Sertoli cell tumours.
Secondary testicular cancers
Cancers that start in another organ and then spread to the testicle are called secondary testicular cancers. These are not true testicular cancers – they are named and treated based on where they started.
Lymphoma is the most common secondary testicular cancer. Testicular lymphoma occurs more often than primary testicular tumours in men older than 50. The outlook depends on the type and stage of lymphoma. The usual treatment is surgical removal, followed by radiation and/or chemotherapy.
In boys with acute leukemia, the leukemia cells can sometimes form a tumour in the testicle. Along with chemotherapy to treat the leukemia, this might require treatment with radiation or surgery to remove the testicle.
Cancers of the prostate, lung, skin (melanoma), kidney, and other organs also can spread to the testicles. The prognosis for these cancers tends to be poor because these cancers have usually spread widely to other organs as well. Treatment depends on the specific type of cancer.