Mum Maggie, 48, a fitness fanatic and avid cyclist, was hit by acute lymphoblastic leukaemia in the summer of 2012, just as she and husband Joe, 54, were training for a John O’Groats to Land’s End bike ride in aid of Help For Heroes.
To make the family’s predicament worse Lewis’s parents and little brother Oliver, 10, were based with the military in Belgium, while the swimmer was stuck in Sheffield training for the British national championships.
“We all knew I would rather be with them but we agreed there was no point stopping everything,” says Lewis. “All I wanted to do was see her but we decided I would stay and train.”
So while Maggie went through chemotherapy Lewis, 22, carried on training for his 200m individual medley race.
“When I saw her in hospital it was two months later and she had lost all her hair and a lot of weight. It was awful to see her so ill. I felt I needed to do something.”
Swim4Leukaemia was the result, an attempt to raise research funds and to break the world record for a relay of 100 swimmers each swimming 100m.
The young sportsman signed up current and former British team members including Rebecca Adlington, Liam Tancock, Michael Jamieson, Mark Foster, Karen Pickering and Fran Halsall.
“Swimming is one of those sports where everyone is one big family,” says Rebecca. “This obviously means the world to Lewis and his whole family and therefore it means a lot to us.”
In February the team, with Oliver swimming the first leg and Lewis anchoring, achieved the feat in 1hr, 29mins, 3secs, knocking eight minutes off the previous record.
So far they have raised nearly £25,000 for Leukaemia & Lymphoma Research, the charity which is backing a new treatment.
Acute lymphoblastic leukaemia is relatively rare in adults, with 400 cases diagnosed in the UK each year.
It develops very quickly but is often confused with other conditions. Sufferers may experience unusual bleeding, bruising, tiredness and breathlessness and frequent infections, caused by a lack of healthy blood cells and platelets.
The main treatment is chemotherapy but Maggie’s initial course was unsuccessful and it was feared she might not be strong enough to withstand a bone marrow transplant.
Doctors in Brussels sent her home on Christmas Eve 2012, with no further treatment planned.
But in the new year she was offered a lifeline with the chance to take part in a clinical trial of a drug called blinatumomab.
The experimental medicine binds to proteins on the surface of cancer cells and receptors on the patient’s normal white blood cells.
These interactions activate the body’s own immune cells to kill off the cancer.
The treatment worked and by the time a suitable bone marrow donor was found last summer she was well enough for a transplant.
“Without access to the clinical trial the road for mum would have been much more difficult – and potentially fatal,” says Lewis.
Even with the treatment the transplant was not a complete success and Maggie has needed bone marrow “top ups” to aid her recovery.
Thankfully, her latest test results came back clear.
And she could not be prouder of what Lewis has done. “It actually brought tears to my eyes,” she says.
“It choked me up to think that he has been prepared to do all of this and we hope this will help others in the same situation as me.”