Cancer insurance is more common because many basic health insurance plans don’t cover all the costs from a cancer diagnosis. Cancer insurance can cover a wide range of both medical and non-medical costs. Few cancer insurance policies cover every one of the expenses mentioned ie: Co-pays, Deductibles, Hospital stays, Visits to out-of-network specialists, etc. Even the ones that do may still leave “gaps” in your coverage. That means you could be left holding a bill that you’ll be responsible for paying.