A serendipitous event occurred when a man, out of curiosity, used a home pregnancy test of his ex-girlfriend and the test turned out positive. He relayed this information to a friend who made a joke about it on an online site. One of the online site readers insisted that the friend go see a doctor because this could represent a potential testicular cancer. It just so happened that the man did have an early testicular cancer.
The presence of the hormone beta-human chorionic gonadotropin (HCG) is what turns a urine pregnancy test positive. Both men and women have low levels of HCG in their bodies, but the amount that is needed to turn a pregnancy test positive is much higher. The hormone is made during pregnancy by the cells that become the placenta. However, other tumors like the case above can produce elevated levels of HCG. Choriocarcinomas can occur in either men or women and cause elevated levels of HCG. Also other germ cell tumors of the testes called seminomas and nonseminomas can also produce HCG.
I am not advocating that all men take random pregnancy tests to see if they have elevated levels of HCG and potentially testicular cancer. First and foremost, see a doctor because that will be the most reliable and responsible form of testing. And keep in mind that testicular tumors in general are rare. Also signs of testicular swelling, aching or pulling in the abdomen or a lump on the testes are better indicators of a potential tumor which would warrant medical attention. In this case the gentleman in the story was extremely fortunate that this silly event helped him detect his disease.