Everything I have seen says no PROXIMATE cause of testicular cancer is known, only risk factors, so there is no way to be sure steroids cause testicular or any of the many other cancers with which they are associated. It is evidence, but inconclusive; we do not accuse everyone with an STD of promiscuity, but it is "sexually transmitted," not "promiscuously transmitted," and STDs are usually taken to suggest sexual activity, absent another obvious cause and/or certainty NO sexual activity occurred. If someone in a group known for sexual activy had an STD, numerous people testified to seeing them have sex and a test sample they submitted to evaluate a "sexual activity test" were positive, their denial of sexual activity would be suspect, and the STD further evidence against the denial.