This is my last diary.
I have written it ahead of time because I knew there would be a point when I was not well enough to continue.
That time has now come.
When I began writing about having a brain tumour, I did not really know why.
I have not been defeated
That personal style of journalism was never something I was particularly attracted to or interested in reading myself.
But when I was diagnosed back in 2002 I had a strong urge to fight back against what felt like the powerlessness of the situation.
I really wanted to try to make something good out of bad.
I was not sure if what I wrote would be any good and I was not sure if anyone would read it but I wanted to try.
And I also very much wanted to use the diary to maintain my link with my job if I was not well enough to work.
Optimism in dark circumstances
I know now that people have found the diary useful, and it meant a lot to me in particular to know that there were people in a similar situation to me or caring for such people who got something out of it.
The regular feedback from dozens and dozens of people every time I have written has been wonderful, especially in real times of crisis.
I know that it has kept me going much longer than I would have without it and I am grateful.
I am grateful to many people and this is probably the time to let them know.
My oncologist has been superb in his ability to generate optimism in dark circumstances and to provide me with invaluable respite, as has his colleague my neurosurgeon, who has more than once pulled nasty lumps of cancer out of my head with astonishing skill.
I did not see all the members of the teams involved in the craniotomies I had but I know what a superb job they did and how they kept me in comfort and without pain afterwards. They and all the staff involved in my operations and aftercare were first class.
My GP has been unstinting in his support and without his prompt action at the beginning of my drama I believe I would have done nowhere near as well.
The support and professionalism of Macmillan nurses is legendary and mine has been no exception. I clicked with him the minute I met him.
I would also like to say thank you both to the many colleagues and friends at the BBC who have been such a support and especially to the people who manage the department I work for, for their personal support way beyond the call of duty.
What I wanted to do with this column was try to prove that it was possible to survive and beat cancer and not to be crushed by it.
Even though I have to take my leave now, I feel like I managed it.
I have not been defeated.
Thank you once again to everyone who helped me and came with me.
The last phase now will, I know, not be easy but I know that I will be looked after as I always have been.
I will end with a plea. I still have no idea why I ended up with a cancer, but plenty of other cancer patients know what made them ill.
If two or three people stop smoking as a result of anything I have ever written then the one of them who would have got cancer will live and all my scribblings will have been worthwhile.