Over his lifetime, a man's risk of testicular cancer is 1 in 250 ( 0.4 percent). It is most common among males aged 15-35 years.

Micrograph of a seminoma. Image source: Nephron, Creative Commons Attribution ShareAlike 3.0, Wikipedia.
A few facts from a recent study reported by Reuters:
References:
Study finds infertility-testicular cancer link. Reuters.
Testicular cancer, from Wikipedia, the free encyclopedia.

Micrograph of a seminoma. Image source: Nephron, Creative Commons Attribution ShareAlike 3.0, Wikipedia.
A few facts from a recent study reported by Reuters:
- Infertile men are nearly three times more likely to develop testicular cancer than those who are fertile.
- Certain forms of male infertility associated with faulty DNA repair which is also associated with development of tumors.
- During the last 30-50 years, there has been a continued increase in the incidence of testicular germ cell cancers.
- During the same period, there is evidence of a decline in semen quality and fertility in industrialized nations.
References:
Study finds infertility-testicular cancer link. Reuters.
Testicular cancer, from Wikipedia, the free encyclopedia.