Dietary Fat and Breast Cancer, Part 2

Finally, on to part 2.  Let's talk about a study I found through marksdailyapple.com showing that a high fat and cholesterol diet causes faster growth and proliferation of tumors than a "normal" diet.  The study was done in rats; the control group of rats received rat chow 5010, while the other group received a higher fat "Western Diet 57BD."  Looking at the macronutrient breakdown, there appears to be nothing wrong with the diets.  The rat chow diet consisted of 29% protein, 13% fat, and 58% carbohydrates, while the Western diet contained 15% protein, 41% fat, and 44% carbohydrates.  You can read the whole study and find nothing about the actual ingredients in the diets, but a quick Google search will yield you the spec sheets.  Here are the contents of the control group's rat chow:

• Ground corn
• Dehulled soybean meal
• Wheat middlings
• Fish meal
• Ground wheat
• Wheat germ
• Brewers dried yeast
• Ground oats
• Dehydrated alfalfa meal
• Porcine animal fat
• Ground soybean hulls
• Soybean oil
• Dried beet pulp
• Added vitamins and minerals

And for the Western diet...

• Sucrose (31% by weight)
• Milk fat (21%)
• Casein (19 %)
• Maltodextrin (10%)
• Powdered Cellulose (5%)
• Dextrin (5%)
• Added vitamins and minerals

Problem #1 - The Western diet group didn't even receive real food... these are chemically isolated compounds that have been removed from their real-world context.
Problem #2 - Their diet consisted of 31% sugar????  That's their main carbohydrate source.  Sugar.  There's a lot of research showing a link between insulin and cancer growth, and sugar requires a hefty insulin release. Here, here, and here.  And this study, which studied mammary tumor growth, showed that mice fed sucrose had 100% tumor incidence, meaning every single mouse developed breast cancer.
Problem #3 - Casein.  Casein, which is a protein derived from milk, was used in rat studies conducted by T. Colin Campbell, who wrote The China Study.  He found that a diet of just 5% casein promotes tumor growth in rats.  The diet in this experiment has 19% casein.

So how can the researchers claim that a high-fat and cholesterol diet proliferates cancer cell growth?  If they really wanted to test their hypothesis, they would have done their best to keep as many variables as possible unchanged between the two groups.  They wouldn't have fed the experimental group a laundry list of chemically isolated compounds.  So in my mind we have two possible reasons why the researchers would have used a diet full of known cancer-promoting non-food items.  One, they're stupid.  And I refuse to believe they're stupid, because they wouldn't be where they are today without knowing the basics of science.  The second option, which I like, is that the researchers' goal from the beginning was to confirm their hypothesis.  So they fed the rats a diet which, while higher in fat, was also higher in substances which would be sure to cause tumor growth.  I don't know why they would have done this, perhaps there was some influence from the drug or food industries.  Maybe the researchers had giant egos and were so convinced high-fat diets promoted cancer that they didn't want to risk being wrong.  The only thing I know for sure is that this is really bad science.