The link between steroids and health problems has not been established. Watch this expose. According to this there is no formal scientific study that shows any causal link between steriod use and any health problems. Because that is not sensationalistic news, it gets buried.
Further, when one person gets sick a doctor may GUESS at the cause, but they rarely KNOW, especially with something as mysterious as a brain tumor. It takes a large sample of many, many people with the same ailment and medical/drug history to prove something like "steroids give you brain tumors". A single case is not enough. The doctor that said Lyle died from steriods was either guessing or had his own agenda and prejudices.