Green will seek treatment in Birmingham, Ala., after this week's Senior PGA Championship at Aronimink.
'Hubert has always been known for his tenacity and toughness on the golf course, and we are sure that he will battle this illness with the same courage,' PGA Tour commissioner Tim Finchem said Tuesday.
Green, 56, won the 1977 U.S. Open at Southern Hills despite playing the final round under a death threat. The last of his 19 victories came in 1985, when he won the PGA at Cherry Hills by two shots over Lee Trevino.
He also had a chance to win the 1978 Masters. Green led by three shots going into the final round, but Gary Player closed with a 64 and Green missed a 3-foot putt on the final hole to force a playoff.
Green has won four times since joining the Champions Tour.
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