A father's tonsil cancer was detected early because he helped his daughter revise for her biology GCSE.
Jonathan Jenkyn, 43, from Ipswich, who survived a cardiac arrest in 2015, said he was "dodging the grim reaper."
While helping his daughter with the lymphatic system he checked his own glands and found a lump under his jaw.
He was referred for cancer treatment. He was given the "all clear" on Tuesday after being told he "wouldn't see Christmas".
Mr Jenkyn (known as JJ) said he was diagnosed on 1 August with metastatic oropharyngeal carcinoma.
"I was told the therapy I was on was one of the hardest they give, that the type of cancer I had was aggressive and I wouldn't see Christmas.
"If I had done nothing and not got it checked out, it would be a whole different picture as by now I would not be able to eat, drink and I would be suffocating."
He said he was "in awe" of the help he received from Ipswich Hospital, as without it he "wouldn't be here".
He is now raising funds for Colchester and Ipswich Hospitals Charity.
On Saturday, he ran his 274th parkrun. He donated £10 for every personal best achieved.
Graham Rodgers, event director for Ipswich parkrun said: "JJ is one in a million - a gentleman, a fighter, loved by the community, and an inspiration".
Mr Jenkyn said he had been "stupidly lucky".