The testicles are made of several different types of cells and cancer can begin in any of them. The most common testicular cancers types include:
Germ cell tumors
Most testicular cancers — about 95 percent — are germ cell tumors that start in the cells that make sperm. These include two categories:
- Nonseminomatous germ cell tumors account for about 60% of germ cell tumors. These grow and spread faster seminoma tumors and include:
- Embryonal carcinomas
- Yolk sac tumors
- Choriocarcinomas (a rare, very aggressive type)
- Seminoma germ cell tumors make up about 40% of germ cell tumors. These tumor types usually grow slowly and respond well to treatment. These include:
- Classic seminomas
- Anaplastic seminomas
- Spermatocytic seminomas
A tumor may contain both seminoma and nonseminoma cells. In these cases, the tumor is treated as a nonseminomous tumor.
Carcinoma in situ (CIS)
A noninvasive form of germ cell tumors may occur in the testicles. Called carcinoma in situ (CIS) or intratubular germ cell neoplasia, the cells look abnormal under a microscope, but they have not spread beyond the seminiferous tubules where sperm is made. This diagnosis is usually discovered incidentally, when a testicular biopsy is done for another reason, such as fertility testing. Carcinoma in situ does not always progress to an invasive form of the disease and may not require treatment. However, a diagnosis of carcinoma in situ increases your risk for developing invasive testicular cancer. Those with CIS would likely undergo testicular ultrasound every 6 months.
Representing only 5% of testicular cancers, stromal tumors occur in the supportive testicular tissue and sometimes produce hormones.
Secondary testicular cancer
When a cancer spreads from its primary site to another location or organ in the body, this process is called metastasis and the new lesions or tumors are called metastases. Several cancer types, such as lymphoma, leukemia, prostate, lung, melanoma and kidney, are known to metastasize to the testicles. These testicular tumors — sometimes called secondary testicular cancer — are not really testicular cancer because they did not arise from testicular cells but came from the cells of the primary location.
When testicular cancer metastasizes, it is most commonly found in distant lymph nodes, bones, liver and lungs. Advanced and late stage testicular cancer may require a treatment approach that involves high-dose chemotherapy followed by a stem cell transplant. This complex treatment should only be done at accredited centers with high volume experience. Learn more about Roswell Park’s Transplant & Cellular Therapy Center, one of the nation’s top centers for stem cell transplant.