The 47-year-old barman admitted he should should have been diagnosed sooner, but he did not take the signs seriously.
Griffiths was diagnosed with bowel cancer last September.
The First Dates barman is back in hospital following surgery to remove his tumour.
TV star Merlin publicly revealed his bowel cancer diagnosis in September 2021.
The star of the Channel 4 dating show was diagnosed with Stage 3 bowel cancer in September last year.