Breast cancer: menopause and obesity don't mix
BET À DAY
A study reports that excess fat causes hidden breast tumors to awaken by stimulating the production of new blood vessels.
Over 75% of new Breast cancer cases occur in postmenopausal women. In addition to normal aging which, as for all cancers, represents an important risk factor, several studies have shown that certain factors associated with lifestyle such as a sedentary lifestyle, excessive alcohol consumption and obesity can greatly influence this breast cancer risk.
This is especially true when it comes to obesity. After menopause, studies show that the risk of breast cancer is approximately 50% higher in obese women, and these cancers are associated with poorer prognoses and higher mortality.
This association between being overweight and cancer risk involves an increase in an enzyme called aromatase in fatty tissue. This enzyme converts androstenedione into estradiol, which leads to an increase in circulating estrogens and an increased risk of cancers sensitive to the action of these hormones (ER+, in particular).
Another possible mechanism for this increased risk of breast cancer caused by obesity could be linked to the presence of microscopic, so-called dormant, breast tumors in a high proportion of women.
Autopsy studies of women who died of causes other than breast cancer have detected the presence of these microscopic, clinically undetectable tumors in 35% of them1.
Yet less than 3% of these women will develop breast cancer in their lifetime, suggesting that under normal conditions, cancer defenses manage to maintain these tumors in a latent state, harmless to health, but that certain aggravating factors, obesity in particular, could awaken these dormant tumors and cause them to progress to mature cancer.
An influx of blood that awakens the tumors
This possibility is suggested by the results of a study where researchers examined the impact of obesity on the progression of breast cancer2. They first confirmed that obese subjects developed a greater number of tumors than lean subjects and that these tumors were larger and associated with a higher mortality rate.
Further analysis revealed that this greater tumor progression was correlated with an acceleration of new blood vessel formation within immature tumors present in obese subjects.
It has been known for several years that this neovascularization, known as angiogenesis, plays a key role in the awakening of dormant tumors by allowing them to have access to oxygen and nutrients essential for their growth. Researchers have shown that obesity is a factor that promotes this neovascularization, in particular by stimulating the production of growth factors (VEGF and FGF), which will create a proangiogenic and proinflammatory environment near tumors.
The contribution of these new vessels to tumor progression appears to be extremely important, since the administration of a broad spectrum inhibitor of angiogenesis (sunitinib) prolongs the latency of microscopic tumors and reduces both the number and the volume of tumors .
These results suggest that the physiological changes caused by obesity can therefore benefit cancer cells by providing them with an environment favorable to the expression of their destructive potential. < /p>
We cannot say it enough: maintaining a normal body weight is truly one of the main pillars of cancer prevention. If you don't smoke, this should be your priority for cancer prevention.
►1. Nielsen N et al. Breast cancer and atypia among young and middle-aged women: A study of 110 medico-gal autopsies. Br. J. Cancer 1987; 56: 814-819.
►2. Roy R et al. Escape from breast tumor dormancy: The convergence of obesity and menopause. Proc. Natl Acad. Science. USA 2022; 119: e2204758119.