The 42-year-old, whose father died of cancer of the oesophagus, said he underwent surgery for sun spots.
"I've had a number of skin cancers removed off my face," he told Today FM's The Last Word radio show in Ireland.
"When you get a symptom don't ignore it. Do something about it."
Harrington, patron of the Oesophageal Cancer Fund Ireland, was speaking to raise awareness.
"Dealing with cancer is not what it was 10 years ago," said the world number 137 who won the British Open in 2007 and 2008 and the 2008 U.S. PGA Championship.
"Instead of just one treatment they are now looking at combining different types of treatment of dealing with oesophageal cancer.
"Everybody responds differently to treatment and ways of treating cancer are moving on. I see that when I travel the world.
"It is easier to clear these things up at the start rather than waiting until there is a problem.
"You can get treated and go on to live a much longer life."
- cancer of the oesophagus