Around 27,000 cancer patients in the UK are thought to be behind with their energy bills, owing as much as £2.8 million to companies, a charity has warned.
Macmillan Cancer Support made the collective estimate after finding that one in 20 people who have been diagnosed with cancer in the last two years is in debt to their heating provider.
Three in 10 cancer patients said they have been forced to turn off the heating in the last three months when they needed it on to keep fuel bills down, while a third have put their coats or other outdoor clothing on in the house to try to keep warm.
Of those who said they are behind with their payments, almost a quarter (23%) owe more than £200, while almost one in four is behind by £50-£100. The charity said its research suggests that cancer patients are more than twice as likely to end up behind with their fuel payments than the population generally.
It quoted a cancer patient named Gail, from London, who said she fell into "a financial nightmare of debt" after becoming ill and having to give up her job. She said: "I'm still struggling to pay off my fuel bills from last year.
"It means a cold home because I can't afford the heating, wrapping up in extra layers of clothes and worrying about my sons getting ill as a result. At one point I couldn't sleep for four nights worrying about it all."
The findings come as households are braced to see their energy bills soar over the winter following a string of price hikes.
The Fuel Poverty Advisory Group (FPAG) recently estimated that some 300,000 more homes were likely to have been pushed into fuel poverty by this Christmas, meaning they are spending more than 10% of their incomes on keeping their homes warm. It said that recent energy price rises have increased the average annual energy bill by 7%, taking it to £1,247 for direct debit customers and £1,336 for cash and cheque customers.
Mike Hobday, director of policy and research at Macmillan Cancer Support, said: "Our research shows just how dire the financial situation has become for some people living with cancer in the UK. Thousands of cancer patients are falling behind with their energy bills and resorting to turning the heating off, even though it's vital for their recovery that they keep warm. It's high time we put a stop to cancer patients suffering in fuel poverty."
Macmillan surveyed more than 2,000 people living with cancer for its research.