USA Swimming has this fantastic story about Grace Waller, who in 2008 was diagnosed with osteosarcoma, a type of bone cancer. She had to have her kneecap removed, and 6 inches of her femur plus muscle, but still managed to swim through it, switching from breaststroke to long-distance freestyle, ending up with setting the high school record in the 500 freestyle. Amazing.
See also this segment from The Morning Swim Show:
