The 74-year-old singer is among a number of stars to have sent their best wishes to the 'Sweet Caroline' hitmaker - who turns 77 tomorrow (24.01.18) - after he announced he is retiring from touring on medical advice.
Barry wrote on Twitter: ''#Neil Diamond So,so sorry to hear about the great Neil Diamond's illness. I'm rooting for you Neil! Fight on from another Brooklyn boy! (sic)''
Richard Marx admitted he has plenty of ''respect'' for Neil and is delighted he has seen him perform live.
He tweeted: ''So much respect for #NeilDiamond. Feel honored to have seen him live. Wishing him strength and good wishes. (sic)''
Josh Groban wrote: ''Endless admiration and love to you (sic)''
Neil issued a statement on his official website confirming he has been diagnosed with the disease and that he is to hang up his touring microphone with immediate effect, axing the remaining dates of his '50th Anniversary Tour' in Australia and New Zealand.
He said in a statement on his official website: ''It is with great reluctance and disappointment that I announce my retirement from concert touring. I have been so honoured to bring my shows to the public for the past 50 years.
''My sincerest apologies to everyone who purchased tickets and were planning to come to the upcoming shows.''
But he has vowed to continue writing and recording music for a ''long time to come''.
He added: ''I plan to remain active in writing, recording and other projects for a long time to come.''
Neil is to be presented with a Lifetime Achievement award at the Grammys on Sunday (28.01.18).