The 60-second spot, created by Arthur, does not show any of the patient's faces until the final voiceover of an older man who has been through the experience.
The spot premiers today and will air on terrestrial and satellite channels during the daytime, evenings and weekends until September.
The TV ad was written by Lyndsay McMorrow, directed by Lucy Blakstad and produced by Home.corp. Art Direction was by Andy Kelleher.
Macmillan will also run a series of print adverts across national and regional newspapers and magazines. They will also appear on billboards, bus shelters, via door drops and in a number of healthcare environments as well as online.
Hilary Cross, director of external affairs at Macmillan Cancer Support, said: "Cancer is often the toughest fight many people will have in their lives, and sadly there are millions of people affected by the disease.
"We need them to know that there's a team of people is ready to support them and their loved ones at every stage of their cancer journey and beyond.
"One of the key ways of reaching them is through a fully integrated brand advertising campaign. We believe this ambitious campaign will successfully raise awareness of our charity and increase the uptake of our services."