If it's a low protein diet, couldn't the lack of certain aminoacids which promotes cell growth (and by that, also cancer growth) also aid slowing cancer?
The explanation in the article is sort of along those lines, if cancer cells' inability to switch to a protective state is due to their faulty programming always keeping them in a growth mode:
"Essentially, fasting causes a switch in healthy cells from a proliferative state towards a maintenance and repair state. Malignant cells, in contrast, seem to be unable to enter this protective state because of oncoprotein activity, and therefore fail to adapt to nutrient scarce conditions. Instead, fasting deprives proliferating cancer cells of nutrients, growth and other factors, which renders them more sensitive to cancer therapy and increases cell death"
Layman here, just popped into my mind.