I'll be honest with you zipit, I'm not a big fan of these herbal treatments. This idea of "cancer feeding on the sugar" seems a little far fetched to me. I'll tell you something though. Drinking or not drinking carrot juice is not going to "tip the scales" either way in terms of whether the tumour gets worse or better.
It's not that I'm a non-believer of herbal remedies...I think they have their place....but it bothers me when an herbalist claims that eating certain foods is going to make a tumour stay or go away. It just isn't that simple, and the worst part about it is, it gives the patient false hope that the tumour will somehow be "cured".
In my opinion...you are getting the best care from the oncologist that you are seeing, and they will treat your condition the best way they know how. As a person who will be a doctor one day, I feel bad that you've been made to worry over something simple like drinking carrot juice. Go and drink all the carrot juice you want! (but not too much or your skin will turn orange!!
)...don't worry about it affecting the tumour.