The Simpsons co-creator Sam Simon is undergoing chemotherapy after he was diagnosed with cancer.

The 57-year-old writer and producer, who devised the hugely popular cartoon with Matt Groening and James L. Brooks, was told by doctors he has colon cancer last year, but reveals the potentially deadly disease has spread to other vital organs.

Explaining his health battle to radio presenter Jon Leiberman on Howard 101's Leiberman: Live at 5, a spin-off of Simon's pal Howard Stern's daily radio show, he says, "The diagnosis was - I was feeling bad for a couple (of) years, and I was diagnosing myself from television talk shows, so I was taking antidepressants and I was trying to get my testosterone levels up..."

"But then it turned out my primary cancer was colon cancer that had spread to my liver, kidneys, abdominal connective tissues and my lymph system and maybe my brain. They're not sure about that."

After announcing the news last week, he took to Twitter.com to thank fans for their outpouring of support, writing, "I was overwhelmed by all your kind tweets... I have great docs, traditional and alternative, and I plan on beating this. Thanks, again!"

Simon has also worked on hit shows Taxi, Cheers and Friends.