Bill - I am going through the same dilemma right now myself. I have done some research and it seems that it's dependent on whether you've had any break in insurance coverage - if so, there is probably a waiting period of some length before the new insurance would cover any claims related to your cancer. If not, you should be covered. That's one GOOD thing HIPAA has done for us. See this link
http://www.dol.gov/ebsa/faqs/faq_consumer_hipaa.html