Verified answer

Actually it started out as throat cancer, then developed into lung cancer which then spread to his brain so technically everybody is partially right. Being stabbed likely weakened him further which I would imagine hastened things also.

News excerpt:

"Two much less pleasant incidents were next to bring the reclusive performer's name into the press: the first being the announcement of his struggle with throat (and then lung) cancer, and the second being his repeated stabbing at the hands of a mentally unbalanced fan (claiming to be on "a mission from God") who broke into his Oxfordshire home in December 1999. Work on another studio album was underway at the start of the 00s, but its completion was cut short when Harrison's lung cancer spread to his brain in November of 2001."

Lung Cancer.

What a coincidence! I just finished watching Concert for George!

Specifically, he died of metastatic non-small cell lung cancer that spread to the brain.

He is very much missed.

Former Beatle George Harrison, singer, songwriter and guitarist for one of the most world's most noted pop corporations, has died after shedding his fight against melanoma. Harrison died on Thursday at a friend's la house, at 1330 local time, in step with his longtime friend Gavin De Becker.

it was lung cancer, it is sad i really liked the beatles too. I would have LOVED to actully see them preform hey? super good but super sad that two of them have died already. Didn' t the other die on his doorstep like he was killed right there? what has this world come to?

Brain cancer - "metastatic non-small cell lung cancer"that had metastasised to the brain". He was being treated in a hospital in Staten Island NY. If you want to read a very good book on him - read Here Comes The Sun. I took a course with the author a couple years ago. Excellent book. The author was a good friend of George's Pax-C

I believe it was lung cancer. Ironic.