Microsoft co-founder Paul Allen diagnosed with cancer

Vulcan CEO Jody Allen said in a memo to Vulcan employees that Allen, 56, "received the diagnosis early this month and has begun chemotherapy,"

Non-Hodgkin's lymphoma is cancer that originates in the lymphatic system, the disease-fighting network spread throughout the body. In non-Hodgkin's lymphoma, tumours develop from lymphocytes - a type of white blood cell.

"Doctors say he has diffuse large B-cell lymphoma, a relatively common form of lymphoma," Jody Allen, who is Paul Allen's sister, said in the memo. "This is tough news for Paul and the family. But for those who know Paul's story, you know he beat Hodgkin's a little more than 25 years ago, and he is optimistic he can beat this, too."

Allen co-founded Microsoft with Bill Gates in the mid-1970s and worked as the company's chief technologist before stepping down in 1983 - the very year he was treated for Hodgkin's disease.

In September, Allen was ranked 17th in the Forbes 400 list of richest Americans and 32nd richest person in the world, with a net worth of US$11.5 billion.

Allen is also known as a philanthropist and has made contributions to organizations related to health and human services, and toward the advancement of science and technology through The Paul G. Allen Family Foundation.

He currently owns a couple of professional sports teams in the United States - the NFL's Seattle Seahawks and the NBA's Portland Trail Blazers.