Clarke wouldn't reveal the details of the conversation, but stressed he was eager to help in any way.
"I spoke to him and we had a good conversation about various things," Clarke said Friday. "I understand probably more than anybody, well not more than anybody because a lot of people have suffered from it. But he is a good friend. It's very sad news, but it's early stages so we hope all the tests and everything else go as well as we all wish for."
Clarke's wife, Heather, lost her battle with breast cancer in August 2006. Three weeks later, he was selected to the European Ryder Cup team. Amid scenes of great emotion at The K Club in Ireland, he won all three of his matches as Europe retained the Cup.
Clarke, of Northern Ireland, spoke of the assistance he received from the Mickelsons at The K Club.
"They're both really good people and they have been extraordinarily kind to me," he said. "He and Amy helped me through that Ryder Cup, walking on and off with me at the opening ceremony and closing ceremony. Then Amy took my arm and then they took me to the other side, which was supposed to be for players and their wives. Amy got involved in that. They have been very kind to me."
Clarke said it was important to pass on whatever knowledge he has gained.
"I've been through the whole thing," Clarke said. "I know the layman's terms for some of the things they say, and I'm only too happy and keen to pass on whatever little tidbits I can -- what's coming, the ups and downs, what to expect.
"Friendship is more than just golf. You try to help in any way at all. Hopefully, they have caught it early."