Anyone Recovered Muscle Fast After Illness/Cancer?

I have heard of a few people that have done this, just wondering if people thought it was exaggeration or if some here have similar stories. One guy that had trained for a good decade was back to square one after recovering from fairly aggressive cancer. He was a steroid user at his peak and said that he just went on a cycle fairly soon after starting training again, and after about one slightly longer than average cycle (think 4 months) he was back to 90% of his peak.

Reckon it’s BS? I’m not sure, I have seen muscle memory do freaky fast things with my own body, I guess combining that ability with steroids could mean his story is plausible.