Swimmer Archie Goodburn is to meet the prime minister later after making a tearful plea for more investment to be put into brain cancer research.
The Scottish athlete, who was diagnosed with three inoperable brain tumours two years ago, said the Downing Street meeting offered a "unique opportunity for change".
He previously called for Andy Burnham to introduce a brain cancer lead to give patients a chance to "fight for their lives" during an appearance on BBC Breakfast.
Goodburn, 25, cried while looking down the camera, saying he was "on my knees begging" for help to ease the "unbearable suffering" of patients and their families.
Burnham later contacted Goodburn on social media to set up the meeting at Downing Street.
Goodburn reached the final of the 50m breaststroke at the 2026 Commonwealth Games in Glasgow.
He said he went for medical tests after suffering from numbness and seizures during training for the 2024 Olympic trials.
He was diagnosed with three large oligodendrogliomas, a rare type of cancer which can affect the brain and spinal cord.
The Edinburgh-born swimmer underwent chemotherapy and radiotherapy to treat the tumours, but surgery to remove them was found to be impossible.
Burnham invites swimmer Goodburn to meeting after cancer funding pleaAttributionSportPublished4 August
Burnham invites swimmer Goodburn to meeting after cancer funding plea
Swimmer Goodburn diagnosed with inoperable brain tumoursAttributionSportPublished27 June 2024
Swimmer Goodburn diagnosed with inoperable brain tumours
During his appearance on BBC Breakfast, Goodburn called for more resource to be put into research and care, and for clinical trials happening elsewhere to be brought to the UK.
"Please establish a national brain cancer lead and give us a chance to fight for our lives because the things that patients are going through out there are unbelievable and so unjust," he said.
"There are clinical trials around the world, in the US, in Australia, in China, that could change lives. We are not seeing them in the UK and it is unfair and unjust.
"Please invest and make the difference. I'm on my knees begging for – not just my own life – but for those of my best friends and those that are affected and the families around the country."
Goodburn added: "This has to change. It's been going for too long and the suffering is unbearable."
Before the meeting, Goodburn said he hoped it would be a "unique opportunity for change".
"We cannot accept the status quo in the system, we cannot be risk-averse. People are dying," he said.
"My advocacy has opened doors to have conversations at the highest level of government about the injustices faced by the brain tumour community and campaign for change for myself and for them.
"But I hope I can also inspire people on an individual level."
Charity Brain Tumour Research said the disease was the cancer most likely to kill patients under 40 in the UK.
They said charities made up more than 75% of the total national investment in brain tumour research, with the government funding sitting at 25%.
The Rare Cancers Bill, led by Edinburgh South West MP Scott Arthur, became law earlier this year.
The legislation aims to incentivise research and investment into the treatment of rare types of cancer, defined as those affecting fewer than 1 in every 2,000 people.
Goodburn said that did not go far enough and a dedicated brain cancer lead would allow for greater focus on specific research and trials.
Arthur said the act was "vital" to driving research needed into the condition, but that Goodburn's meeting with Burnham could lead to further work in the field.
"There is real opportunity in the sector to dismantle the barriers to research that charities, clinicians, and researchers have known about for decades," he said.
"Having met Archie a number of times I know he is a fantastic advocate for the brain tumour community.
"I hope his meeting with the prime minister is a moment for concrete progress to be made."
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