@steveron
I do know people who were allowed to see providers outside of their Medicare Advantage network, but it is usually when an in-network provider referring them because the care required was not provided by in-network providers. The Medicare Advantage company had to approve.

My understanding of Cancer Insurance or Critical Illness insurance it is designed to be used in addition to major medical health coverage, but not replace it. I cannot specifically answer if you would be able to get Cancer Insurance, but I asked an insurance broker about once at Health Expo. Because I had previously had cancer I was not eligible for the policies he sold. He was selling a critical illness policy that included cancer.

If looking at cancer insurance, check policy carefully to determine what is and isn’t covered. Things to look for are:
• Preexisting conditions
• Waiting period
• Type of cancer / illness it covers

If looking at changing your Medicare Advantage plan outside of normal enrollment plan, check the Medicare site for exceptions for changing:
https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan/special-enrollment-periods