Marma,
This is very good advise and consistent with what is promoted at my CCC and most if not all other (great) CCC's in my area. So much so that my CCC (Sharp Foundation) holds classes and encourage all their cancer patients to attend.
Also Diet was the subject at our last OC Support Group meeting and it was very well attended. An Oncology Nutritionist from 'The Scripps Institute' gave an excellent presentation with lots of handouts, including Avocados! Spirulina came up as did blueberries and the like -- some of this may be iffy, but none of it is bad. I know several long term survivors in the group that swear by it.
Diet was also a significant part of another recent and great presentation to the group from a 'Kaiser Permanente' Swallowing and Speech Therapist and she had an excellent and extensive diet plan for those with swallowing difficulties (of which we have several).
PS just got a bad email that a Support Group friend has had a recurrence and is at the 'UCSD Moore CCC' for surgery

So we need to cover all the bases - good diet, exercise, a great CCC team and a little luck

Sadly, still too many of us don't make it.