2023-10-06 10:36:19
Obesity is associated with an increased risk of breast cancer (mainly in postmenopausal women) and worsens the prognosis of this pathology. But the connections between these two major public health problems remain poorly understood: they are the subject of all research attention. To date, the main hypothesis suggests disruptions in the functioning of hormones and growth factors (estrogen, insulin, etc.), as well as a chronic form of inflammation. To learn more about this, researchers from Yale University and Cornell University wanted to combine laboratory experiments and computer simulations for their study, which received a $2 million grant from the National Institutes of Health. The latter started from the observation that most breast cancers originate in the epithelial lining of the milk duct (the conduit through which milk is brought to the nipple). As it exits the milk ducts, it enters adipose tissue, a fatty connective tissue made up of cells called adipocytes.
Additionally, the number of cancer cells that progress into adipose tissue and whether they reach the vasculature of the adipose tissue are critical factors that determine the degree of cancer mortality. “ If the cancer cells enter a blood vessel, then there is a risk of metastasis, leading to a poor prognosis for the patient. “, says Corey O’Hern, professor of mechanical engineering and materials science, physics and applied physics. Obesity has been shown to be an important factor facilitating the process of cancer invasion. To understand why, most current research focuses on the biochemical aspects of cancer. But the scientific team wanted to focus instead on how the altered physical properties of adipose tissue can affect the invasion of cancer cells. “ The fatty tissue surrounding the breast ducts can shrink and grow depending on a number of factors, but how these fat cells function in breast tissue is not well understood. », he adds.
“This work could pave the way for new, more effective treatments”
Adipocytes are larger than cancer cells and it turns out that these cells that store fat in the body swell to even larger sizes in cases of obesity. “DTherefore, if adipocytes swell and pack tightly during obesity, it would appear that cancer cells would not be able to move through the densely packed adipose tissue. “, says Corey O’Hern. But the researchers’ preliminary results show that when cancer cells interact with adipocytes in mice with severe obesity, this causes lipolysis (a natural phenomenon of “destocking” of body fat in adipose tissues) in which the adipocytes shrink. However, this shrinkage allows the creation of pathways allowing cancer cells to penetrate the adipose tissue. “ Lipolysis can nourish tumor cells so they can grow faster, but it also shrinks surrounding tissue, which will give them a new environment to spread. »note the researchers.
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Ultimately, they wish to deepen their research, in particular to define the physical properties of adipose tissue in obese people which contribute to increased tumor invasion in breast cancer. In doing so, “ This work could pave the way for new, more effective treatments for breast cancer. “, they conclude. Note that in France the Foundation for Medical Research issues the same observation, namely that “adipocytes are a major constituent of the tissue which forms the breast and that researchers have shown that these fat cells are capable of interacting with breast cancer cells located nearby, which promotes their aggressiveness and their ability to invade other tissues. This effect could be amplified in obese patients: this would explain why excess fatty tissue could constitute a factor aggravating the severity of this type of cancer. » For the organization, improving their knowledge on the role of fatty tissue in breast cancer in obese patients would also make it possible to ultimately offer new treatments in these high-risk patients.
The National Cancer Institute (INCa) affirms for its part that nearly 19,000 new cases of cancer in France are attributable to excess weight (a concept encompassing overweight and obesity) in 2015, or 5.4% of the population. all new cases of cancer. “ In overweight and/or obese people, there is an increase in the levels of several hormones. These factors are notably involved in the proliferation of cancer cells. », he affirms, not without specifying that overweight and obesity are associated with an increased risk of developing cancer for 14 different locations. The first is none other than breast cancer, the cancer most frequently observed in women in France, as in the European Union and the United States. But the opposite is also true: a correct weight, that is to say a body mass index between 18.5 and 25 kg/m2 combined with a healthy and balanced diet as well as regular exercise. Physical activity can reduce the risk of cancer. The INCa thus considers that “ 40% of cancers could be avoided if we changed our daily behaviors. »
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