Apple CEO Steve Jobs is recovering in hospital following surgery to remove a cancerous tumour from his pancreas, it has been revealed.

In an email message to employees, sent from his hospital bed, Jobs explained that the cancer is an islet cell neuroendocrine tumor. Symptoms of the cancer include sweating, tremors, rapid heart rate, anxiety, dizziness, headaches, clouding of vision and behavioural changes.

This form of cancer can be cured by surgical removal if diagnosed early, as was the case with Jobs. He will require no chemotherapy or radiation treatment, according to the email.

"I had a very rare form of pancreatic cancer called an islet cell neuroendocrine tumor, which represents about 1 per cent of the total cases of pancreatic cancer diagnosed each year, and can be cured by surgical removal if diagnosed in time (mine was)," stated Jobs/

Jobs expects to return to work in September. During his absence, Apple will be run by executive vice president of worldwide sales and operations Timothy Cook.

Jobs wrote: "I will be recuperating during the month of August, and expect to return to work in September. While I'm out, I've asked Tim Cook to be responsible for Apple's day-to-day operations, so we shouldn't miss a beat. I'm sure I'll be calling some of you way too much in August, and I look forward to seeing you in September."

Apple director Bill Campbell told Associated Press: "The surgery was hugely successful, and the prognosis is excellent. We feel very relieved and optimistic about the future."

Not enough Jobs

But despite optimism within the company, Jobs' illness and absence may concern investors in Apple and Jobs' other company, Pixar, both publicly traded companies.

Creative Strategies analyst Tim Bajarin told the San Francisco Gate: "Obviously, Steve is so integral to the company that you have to be concerned if the illness has any long-term effects on him. Having him come back in full force is critical since he's so much of a visionary and the real direction of the company.

"But for the short term, Jobs' absence shouldn't cause any significant issues since Apple has many of its more immediate products already in the pipeline. If he's only out for a month, I don't think Apple even skips a beat."

However, IDC analyst Roger Kay said: "Jobs' illness highlights the pressing need for Apple to develop a succession plan. They need to anticipate a world where he isn't running the company, something they have up to now refused to do."