can't get insurance coverage

My 25 year old son has recently completed his treatment for testicular cancer. He is still a college student since the cancer interrupted his studies. He is now ineligible for my medical insurance since he turned 25. I can cover him for one year under COBRA, which is very expensive, but no insurance companies will pick him up after that until he reaches the 3 year cancer free diagnosis. He lives in SC. Who can I appeal to for coverage? He needs to continue his follow up tests for 5 years.