Around eight months ago, father-of-two Mark Williams couldn’t make it up a flight of stairs without oxygen, but now he has completed a gruelling 100km cycle ride.

The 54-year-old, from Rainham, was diagnosed with bowel cancer in February 2012.

He was training for the Paris Marathon but his times were getting worse.

When he spotted blood and went to see his GP, he was referred to a specialist who confirmed he had cancer. The IT consultant said: “I was so shocked, I stood up and fainted. I think I’d been in complete denial about what was happening and my brain couldn’t take it in.”

Mr Williams started radiotherapy and oral chemotherapy to shrink the tumour in his lower bowel and in June 2013 had a 12-hour irreversible colostomy operation.

However, just over a year later a check-up found the cancer had come back. “It was variously described as inoperable, incurable and terminal,” Mr Williams said. “That was devastating.”

Before starting chemotherapy, he went on holiday with his wife, Fulya, and their daughters, Jessica, 16, and Lucy, 13, to Florida.

After months of treatment, the drugs stopped working and surgeons were reluctant to operate, but Mr Williams convinced King’s College and Guys Hospital to do the operation.

He had numerous operations over the course of three months as surgeons removed virtually half of his lungs. He said: “My breathing was understandably very poor and I left hospital in a wheelchair.

“We live in a town house and the bedroom is on the second floor. I couldn’t walk a few yards or get up the stairs. It was so bad I ended up ordering oxygen off the internet.

“But over time I made it to the first floor and then the second.

“And then I made it to the kitchen without being out of breath and it was so exciting!”

Mr Williams’ lung capacity improved so much that he was able to get back on his bike and organised a 100k charity bike ride along the Kent coast with 14 friends.

So far they have raised more than £5,500. He is currently cancer free, but is aware the disease is likely to return. Mr Williams said: “I’m fully motivated to use the extra time I’ve been given to raise money to help prevent others from going through a similar experience.”

He has now been made the face of Cancer Research UK’s Stand Up to Cancer campaign in Kent.

Mr Williams added: “The last couple of decades has seen massive improvements in early diagnosis, treatment, and survival rates.

“More and more people are surviving but that’s not a lot of comfort to the thousands of families who still have to say goodbye to a loved one.”

Each day around 130 people are diagnosed with cancer in the South East.

Cancer Research UK is appealing for people to join the Stand Up to Cancer campaign alongside doctors, nurses, scientists and celebrities to help raise money and awareness for its life-saving research.

Lynn Daly, the charity’s Kent spokesman, said: “We would like to thank Mark and Fulya for standing up to cancer with us.

“Their experience brings home the fact that one-in -two of us will be diagnosed with cancer at some point in our lives.

“We’re on the brink of a revolution in cancer research – thanks to new treatments, screening and earlier diagnosis, more people are surviving the disease than ever before.

“But we can’t afford to stand still. It’s time to take a stand against cancer, raise money and save lives.

“Research is our weapon against this terrible disease and we’re calling on people in Kent to stand up to cancer and show their support.”

This year’s campaign culminates on Friday, October 21, with a live TV show on Channel 4.