Thousands of cancer patients are being denied holiday insurance or being forced to fork out "sky-high" costs to ensure they have proper medical cover while abroad, a charity said.
While the average cost of travel insurance is £37, thousands of people with cancer are paying £1,000 or more, Macmillan Cancer Support said.
Some prices and policies reflect an outdated view of cancer as an illness that only affects a small number of people or that those who have cancer are facing a "death sentence", the charity said.
But it said that by 2020 one in every two people will get the disease at some point in their lives. And cancer patients are now twice as likely to survive at least 10 years after diagnosis than they were at the start of the 1970s.
It has called on the insurance industry to ensure people living with cancer are not priced out of the market.
A new poll conducted on more than 2,000 cancer patients found that 2% are being denied insurance policies despite their cancer being diagnosed more than a decade ago.
Extrapolating the figures, the charity estimated that 8,500 British holidaymakers who applied for travel insurance were unable to get a policy despite the fact that they were diagnosed more than 10 years ago.
Meanwhile, an estimated 7,500 Britons who have ever had cancer and took out single trip or annual travel insurance paid £1,000 or more for their policy
On average, people with cancer paid £133 for their policies - nearly four times the average cost of an annual travel policy for the general public - just £37, the charity said.
The poll found that 18% of people who had cancer and took out travel insurance paid £200 or more for cover.
"For many people with cancer, getting travel insurance can turn a dream holiday into a nightmare," said Macmillan Cancer Support chief executive Lynda Thomas.
"Every day, we hear from people who have longed for a holiday as a chance to recuperate, to celebrate the end of their treatment, or to spend precious time with friends or family, only to have those plans shattered by issues with travel insurance.
"It's not good enough that they are being denied travel insurance or charged sky-high prices.
"Even those who were diagnosed a decade ago are being written off as 'uncoverable'.
"We want insurance providers to give people with cancer a break.
"Travel insurance policies should be clear and fairly priced for everyone, including people with cancer."
The charity has called on the insurance industry to use more "accurate, relevant and tailored" data in their policies.
It has also called on insurers to give clearer explanations about how quotes have been calculated and what an exclusion would mean if someone needed to make a claim.
A spokeswoman for the Association of British Insurers (ABI) said: "Travel insurance is widely available for people who have long-term and serious health conditions, including people who have various stages of cancer.
"If a customer is struggling to find cover via comparison websites, we would strongly advise approaching a specialist provider, who should be able to offer insurance based on their particular situation.
"Travel insurers pay out more on medical expenses than any other type of claim and it is common for those with serious pre-existing conditions like cancer to pay more for their travel insurance as the costs of medical treatment are often significantly higher."