Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

Testicular cancer is the uncontrolled growth of abnormal cells in one or both testicles (testes). The testicles are the male sex glands. They are located in the scrotum, behind the penis. They produce testosterone and other male hormones. The testicles also produce and store sperm, the male cells needed for reproduction.

Once testicular cancer develops, it can remain within the testicle, or it can spread to lymph nodes in the abdomen or pelvis. If it is not detected and treated, testicular cancer eventually can spread to the lungs, brain, liver, and other parts of the body. Certain types of testicular cancer are more likely to spread than others.

Most testicular cancer patients are between the ages of 20 and 40. Though testicular cancer accounts for a very small percentage of all cancer cases in men, it is the most common cancer in younger men.

Testicular cancer is more common in white men than in black men. Men who had an undescended testicle as infants have an increased risk for testicular cancer. (An undescended testicle is one that remains in the abdomen or groin instead of moving normally into the scrotum before or soon after birth.) Men who have cancer in one testicle have a small lifetime risk of developing it in the other one, whether or not they had an undescended testicle.

Other men also are at increased risk for testicular cancer, including men who have

  • close relatives who have had testicular cancer

  • an undeveloped testicle

  • been diagnosed as HIV positive

  • certain genetic conditions, such as Down syndrome or Klinefelter syndrome.

Some experts think that these conditions also increase risk:

  • mumps infection of the testicle

  • maternal exposure to diethylstilbestrol (DES)

  • exposure to Agent Orange.

Sometimes, testicular cancer is found when a man is being evaluated for infertility.

The two main types of testicular tumors are germ cell tumors and tumors of supportive tissues, or stromal tumors. Nearly all testicular cancers start in germ cells. These are the cells that make sperm.

There are two types of germ cell tumors: seminomas and non-seminomas. Seminomas tend to grow slowly. These cancers usually stay within the testicles for a long time without spreading. Non-seminomas form in more mature germ cells. They are more likely to spread, especially to lymph nodes. Lymph nodes are bean-shaped structures throughout the body that produce and store infection-fighting cells.

A small percentage of testicular cancers are tumors of supportive tissues. They begin in the tissues that support the testicles. These stromal cancers are called Sertoli cell tumors and Leydig cell tumors.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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