If you’re not sure why you should check, Wikipedia explains why:
Testicular cancer has one of the highest cure rates of all cancers with an average five-year survival rate of 95%. If the cancer has not spread outside the testicle, the 5-year survival is 99% while if it has grown into nearby structures or has spread to nearby lymph nodes, the rate is 96% and if it has spread to organs or lymph nodes away from the testicles, the 5-year survival is around 74%. Even for the relatively few cases in which cancer has spread widely, chemotherapy offers a cure rate of at least 80%.
Courtesy of my wife