According to the American Institute for Cancer Research, maintaining a healthy weight can prevent 22% of gallbladder cancers, 5% of ovarian cancers, 33% of esophageal cancers, 19% of pancreatic cancers, and 11% of advanced prostate cancers. Add activity to the picture and a healthy weight can prevent 50% of colorectal cancers, 33% of breast cancers, 30% of liver cancers, and 59% of endometrial cancers.
Obesity has long been associated with an increased risk of several cancers. Men who are obese have a 30-70% increased risk of colon cancer. 1 In fact, obesity may even be associated with worse cancer outcomes (this includes cancer recurrence or death).
We've known the link between obesity and a higher cancer risk for many years. What we haven't clearly understood is why- why does higher body fat increase the risk of cancer. Now, thanks to new research, we have a clearer understanding of how fat cells encourage tumor formation.
What We've Known
Up until now we have seen studies show several ways fat may play a role in cancer. For one thing, increased body fat increases inflammation in the body. Chronic low-grade inflammation may promote the initiation and progression of cancer.
Obesity may also weaken the body's immune system defenses. This may allow tumors to grow and spread.
The Link Gets Clearer
The review, published in Cancer Prevention Research, found that there may also be communication (chemical signaling) between fat and tumors that may encourage tumor growth. Researchers believe that finding a way to "interrupt" this communication may lead to new ways to help prevent cancer.
Several studies that were reviewed discuss specific types of fat cells - adipose stromal cells - that are able to enter cancer lesions and promote the growth of tumors. Interestingly, obese people with cancer had more of these types of fat cells than thinner people.
Another way body fat may increase cancer risk, according to the review, is by increasing levels and bioavailability of growth factors. While these growth factors are normally used by the body for the proliferation and programmed death of cells, they can also promote the growth of certain cancers.
Even the location of body fat can incluence the development of some cancers. According to the review, fat tissue is typically near colon and rectal cancers and in the same environment of breast tumors.
The bottom line: obesity is anything but inert. It is actively cancer-promoting. Knowing this can be empowering. For the longest time, cancer was viewed as something largely out of our control. While there is no guarantee, it appears maintaing a healthy body fat percentage can significantly impact cancer risk.
Cancer Prev Res (Phila). 2017 Sep;10(9):494-506. doi: 10.1158/1940-6207.CAPR-16-0322.