Cancer patients are having to cut back on food and essentials to afford living costs amid warnings inflation - the measure of the prices of everyday goods - could reach highs of 9% by the end of the year.
Lara Burwell's immune system has been weakened since she was diagnosed with thyroid cancer in 2019.
The 30-year-old is currently undergoing treatment.
She lives with her partner and young son in Somerset and used to work as a Nursery Manager.
“For me, cancer and the spiralling cost of living is the worst possible combination," Lara said.
"No matter what cuts we make to save money, we straight up can’t afford life anymore."
The young woman says it has put pressure on her health and she now has severe anxiety.
"I have overwhelming anxiety as all the money worries add up, and on top of this I am so fearful about how our standard of living will affect my cancer recovery.
“We’ve completely cut out heating, which is horrible as my treatment means I get really cold, but even with that saving I’m not sure we can afford the rent anymore.
"The cost of petrol and parking to get to hospital for treatment three times a week is mounting, and alongside all of this, the process of getting personal independence payments to help with the life-changing side effects of my cancer has been relentless.
"It’s taken a three-year battle and two more tumours for me to finally receive the support I’m entitled to."
Nearly a third of people with cancer have resorted to wearing coats or dressing gowns indoors more to try to stay warm without spending extra, according to Macmillan charity.
One in six have been washing clothes or bedding less - or not at all - to try to keep costs down, the figures show.
The charity said nearly a quarter of people with cancer agreed with the statement: "It feels like I just can't afford life at the moment."
Since December, 24% of people who have had a cancer diagnosis said they had been buying less food, or making fewer hot meals, to try to cope with the surging cost of living.
Macmillan's research indicates 83% of people with cancer in the UK experience some kind of financial impact from their diagnosis, and for those affected this reaches an average of £891 a month, on top of usual spending.
Dr Anthony Cunliffe, Macmillan national clinical adviser for primary care, said: "At a time when people living with cancer need their health to be their priority, it's devastating to hear the toll the cost-of-living crisis is taking on the wellbeing of so many people.
"Nutrition, warmth and hygiene are all vital in keeping people with cancer well enough for treatment and aiding their recovery, and to hear that people are being forced to deprive themselves of these essentials is hugely concerning.
"I'd urge anyone affected by cancer who has concerns or questions about the impact of the cost-of-living crisis on their health and wellbeing to get in touch on Macmillan's Support Line. We're here to make sure you get the support you need."
Macmillan said it has seen a high level of demand for its financial need support services over the past few months, with the number of calls to the support about energy jumping by 87% since the energy bill price cap came into effect in April, compared with a year earlier.
Christopher Jones, energy team leader on the support line at Macmillan Cancer Support, said: "Every day we are hearing from more and more people living with cancer who are feeling the enormous pressure of the rising cost of living, on top of the extra costs a diagnosis can already bring.
"We used to hear about people choosing between eating and heating, but now we are hearing from people who can't afford either.
"People with cancer need to live, not just survive, and we are urging anyone worried about money to access the support available from Macmillan. We are here to make sure people get the help they need and deserve."
More than 2,000 people across the UK who have had a cancer diagnosis were surveyed.
