What we know and don't know about testicular cancer risk

Testicular cancer develops when cells in the testicle grow abnormally and form a tumor. The exact reason this happens in any individual man is usually unknown. Researchers have identified some factors that appear more often in men who develop testicular cancer, but having one or more of these factors does not mean a man will get the disease. Most men with risk factors never develop testicular cancer, and some men without any known risk factors do.

The most consistent finding is age: testicular cancer occurs most often in men between 20 and 35, though it can happen at any age. Beyond age, the picture becomes less clear. No single cause has been found, and testicular cancer is not contagious, hereditary in most cases, or preventable through lifestyle changes.

Key Takeaways

  • Testicular cancer has no single known cause, and most cases occur in men aged 20 to 35 without an obvious reason.
  • A history of undescended testicle (cryptorchidism) is the strongest known risk factor, even if the testicle was surgically corrected.
  • Family history of testicular cancer or certain genetic conditions may increase risk, but most men with these factors do not develop cancer.
  • Monthly self-examination can detect lumps or changes early, when treatment is most effective, though this is not prevention.

Undescended testicle as the clearest risk factor

An undescended testicle—called cryptorchidism—is the strongest risk factor identified so far. Normally, testicles descend from the abdomen into the scrotum before or shortly after birth. In some boys, one or both testicles do not descend or descend incompletely. This occurs in roughly 1 in 100 newborn boys, though the rate is higher in premature infants.

Men who had an undescended testicle have a higher risk of testicular cancer in that testicle, even if it was surgically moved into the scrotum (a procedure called orchiopexy). The risk also appears slightly elevated in the other testicle, even though it descended normally. Surgical correction in childhood lowers the risk compared to leaving the testicle undescended, but does not eliminate it entirely. The reason undescended testicles carry this risk is not fully understood.

Family history and genetic factors

Men whose father or brother had testicular cancer have a higher risk than the general population, though the absolute risk remains low. If a close relative had testicular cancer, the risk is roughly 8 to 10 times higher than average—but average is already rare, so this still means most men in this situation will not develop cancer. The genetic basis for familial testicular cancer is not yet clear, and no routine genetic test can predict who will develop it.

Certain genetic conditions also appear linked to testicular cancer risk. Men with Klinefelter syndrome (an extra X chromosome) or with a history of germ cell tumors in other parts of the body may have elevated risk. Men with a personal history of testicular cancer in one testicle have a higher chance of developing it in the other testicle later, though this is still uncommon.

Factors that have been studied but remain unclear

Researchers have investigated many other potential causes—trauma to the testicle, infertility, hormone exposure, pesticide exposure, and occupational factors—but none has been consistently proven to cause testicular cancer. Some studies suggest a possible link between maternal hormone exposure during pregnancy and later testicular cancer risk, but the evidence is not conclusive and cannot be changed retroactively.

Height and body size have been associated with testicular cancer in some studies, with taller men showing slightly higher rates, but the reason is unknown and the association is weak. Lifestyle factors such as smoking, alcohol use, or diet have not been shown to significantly influence testicular cancer risk. Testicular cancer is not caused by sexual activity, masturbation, or sexually transmitted infections.

Why testicular cancer occurs in young men

Testicular cancer is unusual because it peaks in young adulthood rather than increasing steadily with age like most cancers. The reason for this age pattern is not fully understood. One theory involves the rapid cell division that occurs in testicles during puberty and early adulthood; another suggests that germ cell tumors originate during fetal development but do not become apparent until years later.

The fact that testicular cancer strikes men in their prime working and family years makes early detection particularly important. Unlike some cancers, testicular cancer in its early stages is highly treatable, which is why doctors and health organizations emphasize awareness of changes in the testicles.

What self-examination can and cannot do

Monthly self-examination of the testicles—checking for lumps, swelling, heaviness, or changes in texture—can help a man notice changes early. Early detection matters because testicular cancer found before it spreads has much higher treatment success rates. However, self-examination is not prevention; it does not stop cancer from developing. It is a way to catch it sooner if it does occur.

A man performing self-examination should know what his testicles normally feel like so he can notice any change. The best time is after a warm bath or shower, when the scrotum is relaxed. Any lump, swelling, pain, or significant change in size or weight should be reported to a doctor, though most lumps and changes are not cancer.

When to see a doctor about testicular concerns

A man should see a doctor if he notices a lump in either testicle, swelling or enlargement, a feeling of heaviness in the scrotum, pain or discomfort in a testicle, or any change that seems different from his normal. He should also mention to his doctor if he has a family history of testicular cancer or a personal history of undescended testicle, even if he has no current symptoms.

A doctor can examine the testicles and, if needed, order an ultrasound to determine whether a lump or change is concerning. Ultrasound is the standard imaging tool and can usually distinguish between cancer and benign conditions. Finding something does not mean it is cancer, but prompt evaluation is important.

Frequently Asked Questions

Can testicular cancer be prevented?

No. There is no known way to prevent testicular cancer. Men at higher risk—such as those with a family history or a history of undescended testicle—cannot reduce their risk through any known action. The focus is on early detection through awareness of changes.

Does an undescended testicle always lead to cancer?

No. Most men with a history of undescended testicle do not develop cancer. However, the risk is higher than in men without this history, which is why doctors monitor these men and why awareness of changes is important.

Is testicular cancer hereditary?

In most cases, no. While family history does increase risk, testicular cancer is not inherited in a predictable pattern like some other cancers. Having a relative with testicular cancer means higher risk, but not certainty.

What does a testicular cancer lump feel like?

A lump associated with testicular cancer is typically firm, painless, and felt within the testicle itself rather than on the surface. It may feel different from the normal texture of the testicle. Any new lump or change should be checked by a doctor, as most lumps are benign.

If I have no risk factors, can I still get testicular cancer?

Yes. Many men diagnosed with testicular cancer have no known risk factors. Risk factors increase the likelihood, but testicular cancer can occur in any man. This is why awareness of changes and prompt medical evaluation matter for all men.