A new study by researchers at the Fred Hutchinson Cancer Research Center (Hutch) in Seattle describes how overweight and obese women who significantly lowered their weight through diet and exercise reduced the levels of certain proteins in their blood that play a role in angiogenesis, the process of blood vessel growth that has been intimately associated with the proliferation and survival of cancer cells.
“We know that being overweight and having a sedentary lifestyle is associated with an increase in risk for developing certain types of cancer. However, we don't know exactly why,” explained lead study author Catherine Duggan, Ph.D., principal staff scientist in the public health sciences division at the Hutch. “We wanted to investigate how levels of some biomarkers associated with angiogenesis were altered when overweight, sedentary, postmenopausal women enrolled in a research study lost weight and/or became physically active over the course of a year.”
Interestingly, the research also showed that similar-sized women who exercised regularly, but maintained their usual calorie intake, did not post big drops in pounds or in those suspect proteins—adding to the growing knowledge of information that points to the importance of diet and exercise to maintain proper weight and overall good health. “The fact that exercise alone had little effect was surprising,” Dr. Duggan remarked.
“Many people still think they just need to exercise a little more, and they’ll lose a lot of weight. Doesn’t happen,” noted senior study author Anne McTiernan, M.D., Ph.D., a cancer prevention researcher at the Hutch.
The findings from this study were published recently in Cancer Research in an article entitled “Dietary Weight Loss and Exercise Effects on Serum Biomarkers of Angiogenesis in Overweight Postmenopausal Women: A Randomized Controlled Trial.”
The study was broken up into four arms: a caloric restriction diet arm in which women restricted their calorie intake to no more than 2000 kcal per day that included less than 30% of fat calories; an aerobic exercise arm in which women performed 45 minutes of moderate to vigorous exercise 5 days a week; and a combined diet + exercise arm; and a control arm (no intervention). The study investigators randomly assigned 439 overweight/obese, healthy, sedentary, postmenopausal women, aged 50 to 75, to one of the four study arms to measure the effect of exercise and diet on the circulating levels of proteins related to angiogenesis after 12 months.
Blood samples were collected at baseline and at 12 months. In each of those samples, researchers measured three proteins—vascular endothelial growth factor (VEGF), plasminogen activator inhibitor type 1 (PAI-1), and pigment epithelium-derived factor (PEDF)—that flow through the body and help in the formation of new blood vessels, a process called angiogenesis.
Angiogenesis is a vital function where new blood vessels are formed, for example, during wound healing. Unfortunately, an important part of tumor growth and development is also dependent on having a supply of blood vessels to deliver nutrients and oxygen to allow a tumor to continue to grow. The three measured proteins have been shown previously to be involved in nurturing the growth and survival of cancer cells.
The research team found that women who adhered for 1 year to the caloric restriction and lower-fat eating—or a combination of the diet and workout plans—had significantly decreased levels of the angiogenesis-related proteins.
“Our study shows that weight loss is a safe and effective method of improving the angiogenic profile in healthy individuals. We were surprised by the magnitude of change in these biomarkers with weight loss,” Dr. Duggan said.
Dr. Duggan continued, stating that “while we can't say for certain that reducing the circulating levels of angiogenic factors through weight loss would impact the growth of tumors, it is possible that they might be associated with a less favorable milieu for tumor growth and proliferation.”
The findings do add to a growing body of evidence showing the link between being overweight and having elevated levels of certain proteins associated with a higher cancer risk. Moreover, the authors suggest that they would advise sedentary, overweight, older adults to perhaps use the findings as a motivation to improve their diets and add more cardio.
“Exercise is important for helping to prevent weight gain, and to maintain weight loss, but does not cause a large amount of weight loss on its own,” Dr. Duggan noted. “Our study shows that making lifestyle changes—in this case, simple changes to the diet to reduce weight—can lower the risk factors for cancer.”