The 58-year-old comedian revealed the news on a substack post, as he said he was "not too worried" but also not "delighted to have had two cancers before the age of 60".
"I have blood cancer. And God is determined to make sure I get the funniest cancers possible and this one is called hairy cell leukaemia (HCL)," Herring said.
"The other bad news is that it is incurable. The good news is that it's entirely treatable and will not kill me. It’s pretty annoying to get another cancer just after the other one is basically at the all-clear stage, not least because I can’t do another show and book about it so soon," he continued.
The news comes nearly five years after he said he defeated testicular cancer.
Herring went on to explain that the cancer had been "bubbling" under for a few years.
"It didn’t get any worse and after five years of being tested the doctor said it was probably going to be OK. I’d sort of forgotten about it to be honest. It’s not linked to the testicular cancer. Someone up there just doesn’t like me. But they don’t hate me that much. So keep giving me the flimsiest and easiest to live with and funniest named cancers available," he explained.
The comedian said that he started chemo this week, and expressed his admiration for the NHS.
"I don’t mind waiting for my free cancer treatment. There just seem lots of ways to make the NHS a bit more efficient if only someone would invest properly in the thing. I am very impressed with the care that is taken to make sure everything is correct and they’re giving the treatment to the right person," he said.
"There were dozens of patients and a handful of staff. I am extremely grateful to live in a country with a free health service, as much as I’d love for it to get the money and resources it requires. Rather than being sold off to Nigel Farage’s mates," he continued.
