testicular cancer (tes-TIH-kyuh-ler KAN-ser)

Cancer that forms in tissues of one or both testicles. Testicular cancer is most common in young or middle-aged men. Most testicular cancers begin in germ cells (cells that make sperm) and are called testicular germ cell tumors.

Enlarge
Anatomy of the  male reproductive and urinary systems; drawing shows front and side views of ureters, lymph nodes, rectum, bladder, prostate gland, vas deferens, urethra, penis, testicles, seminal vesicle, and ejaculatory duct.