Losing weight lowered levels of proteins associated with tumor growth

Overweight or obese women who lost weight through diet or a combination of diet and exercise also significantly lowered levels of proteins in the blood that help certain tumors grow, according to a Fred Hutchinson Cancer Research Center study published July 14 in Cancer Research, a journal of the American Association for Cancer Research.

Two study leaders - Dr. Catherine Duggan, principal staff scientist in the Public Health Sciences Division, and Dr. Anne McTiernan, cancer prevention researcher in the Public Health Sciences Division and the article's senior author - are available to provide details on the study and its implications.

The study:

• Measured three proteins that are known to enhance tumor-related angiogenesis - the formation of blood vessels that feed tumors and enable them to grow.
• Was intended to see how cancer-promoting proteins changed when overweight, sedentary, postmenopausal women lost weight through diet or diet and exercise over the course of a year.
• Enrolled 439 healthy women (they did not have cancer), placing each participant in one of four study arms:
  • Calorie- and fat-restricted diet.
  • Aerobic exercise five days a week.
  • Combined diet and exercise.
  • Control (no intervention).
• Found that women in the diet arm and the diet and exercise arm lost more weight and had significantly lower levels of angiogenesis-related proteins, compared with women in the exercise-only arm and the control arm.

The authors said that it is known that being overweight and having a sedentary lifestyle are associated with increased risk for developing certain cancers, but the reasons for this relationship are not clear.

This study shows that weight loss may be a safe and effective way to improve the "angiogenic profile" of healthy individuals, meaning they would have lower blood levels of cancer-promoting proteins. Although the researchers cannot say for certain that this would impact the growth of tumors, they believe there could be an association between reduced protein levels and a less favorable environment for tumor growth.