Troy Austin, 49, had a tumour removed in a four-hour op and is praying that the surgery has saved his life.
Louis’ mum Johannah Deakin, 43, died in December 2016 and his gran Tina -Troy’s mum - died from a rare bone marrow cancer a few months later aged 67.
Troy told The Sun that the op on his liver comes after years of heavy drinking and smoking - but he insists he is a changed man as he paid tribute to the doctors and nurses.
Troy told the newspaper: “The staff have been brilliant. The NHS might get criticised in some quarters but I have had a great service.
“I believe my tumour was down to drinking and smoking.
“I can’t blame it on anything else.
“Each day I was smoking up to 25 cigarettes and drinking six to eight cans of Tyskie, a Polish lager.
“And my diet was terrible. It was Chinese and Indian takeaways and a lot of chips.
“Some days I wouldn’t eat at all but would just drink and smoke. I would drink to celebrate the good times and drink to cope with the bad. Whatever life threw at me I would drink."
Troy and Louis have not spoken in five years and he split with Louis’ mum when the singer was a week old.
He added: "If Louis ever wanted to make contact then I would be happy for that to happen."
Troy had the 1½in tumour removed at Sheffield's Northern General Hospital last Wednesday.
He added: “The crazy thing is I didn't have any symptoms.
"Early diagnosis is everything. I’ve been crying tears of joy because I feel so lucky to have been given a second chance."