The 33-year-old singer and father-of-two was diagnosed with a rare and incurable glioblastoma multiforme (GBM) brain tumour last summer, and admitted his frustration about the limited treatment available due to lack of research.
Park told the All-Party Parliamentary Group on Brain Tumours via video-link: "I’m staggered they can find a cure for COVID within a year but, for decades on end, they haven’t found better treatments let alone a cure for brain tumours.
“Why is it taking so long for clinical trials to come through?”
Since his diagnosis Parker has had chemotherapy and radiotherapy, which have shrunk his tumour to a point that it is described as "under control", but cannot be removed.
The boyband singer said he had struggled with depression since his diagnosis, but said he attributes his mental health struggles partly to the harsh side effects of his treatment, which include nausea, weight-loss and fatigue.
Parker told the committee: "It’s been an interesting journey so far and I’ve experienced moments of real sadness and darkness. Some of those low points I attribute to the level of toxicity in the treatment process.
"It’s truly horrific and disgusting but it was my only choice and I hope it did the job it needed to do.”
Parker is married to actor Kelsey Hardwick and they are parents to daughter Aurelia, two, and son Bodhi, 13 months.
The singer added: “At 33-years-old, to be told you’ve got 18 months to live, is horrendous. We’ve just got on with it and try not to think about it too much. There’s no other option.”
Brain tumours kill more children and people under 40 than any other cancer, yet only 2% of the national investment into cancer research is allocated to brain tumour research.
The Glad You Came singer previously revealed he is currently paying for several drugs privately in a bid to prevent his tumour from growing.
In September Parker joined bandmates Max George, Jay McGuiness, Nathan Sykes and Siva Kaneswaran to perform a special charity concert to raise money for Stand Up To Cancer and the National Brain Appeal.
Watch: Tom Parker says his own brain tumour is 'under control'