It kills four men every day in London - 1,600 every year.
Many of them die because of embarrassment, ignorance or fear.
We're talking about prostate cancer and today ITV - in conjunction with Prostate Cancer UK - has launched "Stand By Your Man".
It's a campaign to raise awareness of the disease - to encourage men to talk about their health
Above all, it's to help save lives.
Nick Thatcher's report contains explicit descriptions about prostate cancer symptoms.
Prostate cancer kills 1,600 men in London every year.
Today, ITV in conjuction with Prostate Cancer UK launches "Stand By Your Man" which is an initiative aimed at saving lives.
ITV News London have been speaking to a family in Wandsworth, whose father had prostate cancer and who died because of a rare fatal reaction to his chemotherapy treatment.
ITV is running an awareness campaign in partnership with charity Prostate Cancer UK, a disease which kills at least one man every hour.
The campaign, Stand By Your Man, is encouraging women to talk to the men in their lives about how prostate cancer can be identified, treated or monitored, which could potentially save thousands of lives each year.
Women who want to pledge their support can do so here.
An information card which you can use to have a conversation with your man and or send to the man in your life.
Actor Neil Stuke has said it is fundamentally important that men from all backgrounds get tested for prostate cancer.
Mr Stuke said: "The most fundamentally important thing that it (the campaign) should do is for men to go and get tested.
"If you are diagnosed with prostate cancer, there is hope and lots of hope."
The actor, who played a character in BBC show Silk who was diagnosed with the illness, is an ambassador of Prostate Cancer UK.
- One man dies every hour from prostate cancer in the UK
- One in eight men will be diagnosed with prostate cancer, the same odds as women diagnosed with breast cancer
- 40,975 men are diagnosed with prostate cancer every year
- 10,721 men die of prostate cancer each year
Today marks the launch of a new short film starring Ray Winstone and Tamzin Outhwaite about prostate cancer.
Father's Day - which also stars Charles Dance, John Simm and Neil Stuke - will screen on this Sunday on ITV4. Watch the trailer below.