I have BRCA1. I have struggled with my weight for my entire life, but my health is fine. I’m often told that one thing that can help prevent cancer is maintaining a “healthy” weight, and I’m considering GLP-1s. Is there any reason to believe that GLP1-s might increase my risk of cancer, given my BRCA1 status?
—Anonymous
For readers who aren’t familiar, BRCA1 is a mutation in a gene that women can inherit from either parent. Women with the BRCA1 gene mutation are about five times as likely as women at typical risk to develop breast cancer. Many women will take steps to actively reduce their risk of developing breast cancer, or at least to not increase it further.
Additionally, there is evidence that women with overweight and obesity are at increased risk for breast cancer, in particular post-menopausal breast cancer. This is thought to be related to the fact that fat cells produce enzymes called aromatases that increase the production of estrogen. Fat cells cause inflammation, too. Inflammation can cause cells to mutate, eventually leading to cancer.
While intuitively it makes sense that losing weight would then decrease your breast cancer risk, thus far there is no definitive data to support that idea. However, if you are going to take a medication to assist with weight loss, you want to be sure that the medication will not offset any benefits you get from losing weight.
A meta-analysis containing data from more than 80,000 women from 50 different clinical trials found that there was no difference in breast cancer incidence between women who took GLP-1 agonists and those who did not. This data is reassuring that GLP-1 agonists do not increase the risk of breast cancer.
Researchers have also been studying whether GLP-1 agonists could play a role in breast cancer treatment. In early studies of a GLP-1 agonist called exendin, together with metformin, it decreased how quickly breast cancer cells grew and divided in the lab. While it is too early to say how effective GLP-1 agonists might be in treating breast cancer, there is mounting evidence that they may be useful for treating a whole host of diseases beyond Type 2 diabetes and obesity.
The upshot: There is no evidence that GLP-1 agonists increase the risk of breast cancer, and losing weight and improving metabolic function may decrease the risk of breast cancer.
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