Testicular cancer develops in the testicles, the male reproductive glands located inside the scrotum. Although relatively rare, it is the most common malignancy affecting younger men, typically those aged 15 to 45. The average age at diagnosis is 33 years old. The vast majority of cases originate in the germ cells, which are responsible for producing sperm. While most diagnoses occur sporadically, a known hereditary component increases risk for a small number of men.
Quantifying the Familial Risk
Testicular cancer is not considered a strongly inherited disease, but clustering within some families suggests genetic susceptibility. The risk is notably increased for an individual with a first-degree relative (a father or brother) who has been diagnosed. This pattern indicates a familial risk, likely involving multiple genes and shared environmental factors, rather than simple Mendelian inheritance.
The risk increase is substantial compared to the general male population. A man whose father had testicular cancer has an approximately four-fold greater risk, while the risk increases eight to ten times if a brother was affected. The genetic mechanisms involved appear distinct from those causing many other hereditary cancers, resulting from the combined effects of several genes involved in testicular development. Overall, less than 2% of all testicular cancer cases are considered familial.
Other Significant Risk Factors
The strongest risk factor not related to family history is cryptorchidism, or an undescended testicle. This condition occurs when one or both testicles fail to move into the scrotum before birth, often corrected by surgery (orchiopexy). Males with a history of cryptorchidism have a significantly higher likelihood of developing testicular cancer, with the risk being up to 7.5 times greater.
A personal history of the disease is another non-hereditary factor. A man who has had cancer in one testicle has a 12 to 18 times greater chance of developing it in the other, though this affects only 3% to 4% of survivors. Demographic factors also play a role, as white men are several times more likely to be diagnosed than Black, Asian American, or Pacific Islander men.
Early Detection and Screening
There is currently no standard population-wide screening test for testicular cancer, making self-awareness and regular self-examination important. Testicular self-examinations (TSE) are recommended monthly, starting around age 15, ideally after a warm shower. The goal is to feel for any painless lump, swelling, or change in the size or consistency of a testicle, as a lump is the most common presentation.
Individuals with identified risk factors, such as a family history or cryptorchidism, should be diligent about performing monthly self-examinations. If any abnormality is noticed, immediate medical consultation is necessary, even if there is no associated pain. A doctor will typically perform a physical exam and may order an ultrasound or blood tests to check for tumor markers.
Finding testicular cancer early significantly improves the prognosis, which is already favorable compared to many other cancers. When localized to the testicle, the five-year survival rate is nearly 99%. Even if the cancer has spread, modern treatments result in a five-year survival rate of 90% to 95%.