Channel 4 will make a global broadcasting first by showing live surgery during an advert break.
The 90 second advert Live from the Inside will show live footage of a colonoscopy from inside the human body.
The footage will show the removal of bowel polyps as it takes place via a camera linked to a flexible tube called a colonoscope.
Although most bowel polyps are not cancerous, some can be, and removing them will prevent bowel cancer developing.
The advert is part of Cancer Research UK's Right Now campaign, which tells the real stories of patients, loved ones and medical staff and shows the day-to-day reality of living with cancer.
The charity aims to show the positive impact research has had on beating cancer and to highlight the importance of investing in research to develop effective tests and treatments.
The surgical procedure will be performed at Cardiff and Vale University hosptial on patient Philip McSparron by Doctor Sunil Dolwani, an expert at removing complex bowel polyps.
Doctor Dolwani will explain what he is doing and what the viewers can see during the live broadcast.
A cancer nurse will answer viewers' questions on the Cancer Research Facebook live stream of the advert, which will also be streamed to Channel 4 social media sites.
There will be 10 second teasers on 16 January on Channel 4 in the run up to the live event.
Viewers will have the chance to see a 60 second version of the ad on the 18 January at approximately 9.30pm in the second break of Channel 4 drama No Offence.
The advert, which will air at approximately 15:25 on 18th January, will show thanks to the research and those working to prevent, diagnose and treat cancer.
Ed Aspel, executive director of fundraising and marketing at Cancer Research UK said: “Broadcasting Philip’s colonoscopy live gives us the opportunity to show one of the many people across the UK who is benefitting from procedures that wouldn’t be possible without research.
"We want viewers to join us to experience the unique insight of seeing live inside the human body, and witness a procedure that can actually prevent cancer from developing.
"Half of us will be diagnosed with cancer in our lifetime so it’s important to break down barriers, encourage conversation, and show the progress that is being made in beating cancer."