http://www.sciencedaily.com/releases/2011/06/110614115037.htm

Mouse study, but interesting:

Krystal and his colleagues implanted various strains of mice with human tumor cells or with mouse tumor cells and assigned them to one of two diets. The first diet, a typical Western diet, contained about 55 percent carbohydrate, 23 percent protein and 22 percent fat. The second, which is somewhat like a South Beach diet but higher in protein, contained 15 percent carbohydrate, 58 percent protein and 26 percent fat. They found that the tumor cells grew consistently slower on the second diet.

This is a good step forward, there are 100+ news articles all over the web touting this study as proof that high-carb diets are linked to cancer.

It only makes sense, cancerous tumors require glucose to grow, without the chronically elevated glucose/insulin/inflammation levels the growth is going to be affected.