The singer, who hit the pop scene with his twin brother Luke in the 1980s, has taken to Twitter.com to ask for a "miracle" for the siblings' mother Carol, who appears to be gravely ill.
He writes, "I am asking for everyone for Only this (sic): pray for rapid healing for my mum Carol Now please. We need a miracle please pray for her now."
The star revealed last year (13) that his mother had been battling the deadly disease, and he returned from his adopted America to be by her side in London.
British Tv star Melanie Sykes was among the first to send well wishes to the twins, writing, "My dear friends LukeGoss & mattgoss and me are praying for a miracle. Their beautiful mother Carol is very ill. Such sad news."