No, the testicular cancer came about before he turned 40. He was recovered sufficiently to make the attempt. As I recall, he ran circa 4:05 in late winter purely on base training, so many of us thought he would do it. But when he tried to do the speedwork, he got hurt. Seems like he tried again at age 41, but the same thing happened and he decided it wasn't going to happen.
Steve is now 47, so it's unlikely to happen at this point.
My memory may be wrong, though . . .