Many insurers are reluctant to cover cancer patients, or anyone with a pre-existing medical condition, because they are considered more likely to make a claim. You might, for example, have to cancel the holiday because of ill health, or seek expensive medical treatment while you are away.
But it’s not impossible to arrange travel insurance if you have a pre-existing condition – and there are usually two options. Some mainstream insurers will agree to insure your trip, but will exclude cover for any claim that is related to cancer. So, if you have to cancel your trip because the cancer makes you too ill to travel, or you have to go into hospital on holiday for cancer treatment, or as a result of an illness caused by the cancer, then you will have to pay the cost out of your own pocket.