We know that obesity increases the risk of getting some types of cancers. But it isn’t just your chance of getting cancer that obesity can affect, there are other factors involved. For example, obesity may interfere with the effectiveness of a common drug that is used to fight breast cancer in post-menopausal women, accoridng to an Australian study. A short version of the clinical explanation is that aromatase inhibitors (AIs) are pills that block the production of estrogen in post-menopausal women by blocking an enzyme called aromatase. Aromatase turns the hormone androgen into small amounts of estrogen in the body, which can lead to cancer growth for types of breast cancer called estrogen receptor-positive. With the AI treatment there is less estrogen available to stimulate the growth of hormone-receptor-positive breast cancer cells.
The study, a systematic review, used eight earlier studies to assess the effect of obesity on AI efficacy in post-menopausal breast cancer treatment. “The review showed a trend towards a negative effect of obesity on AI efficacy, but the size of the effect and whether it is the same with all AIs (there are 3 different types) is difficult to determine,” found the study. AIs may be less effective in obese women due to the greater quantity of aromatase in peripheral fatty tissue.
Jaime Ponce, MD, bariatric surgeon in Tennessee, said “This is another study that supports the increase incidence of cancer in patients suffering from obesity. Evidence has shown in other studies that the incidence of cancer was 80 percent less after bariatric surgery compared to the control group of morbid obese patients, with the largest reductions seen in breast and colon cancers.”
Earlier research showed that obesity may also decreases a woman’s chance of surviving breast cancer. The study found that younger women who are obese have a 34% increased risk of dying from their breast cancer. The study, however, did not find the same risk for post-menopausal obese women. You can read more about the study here.