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 in Cancer Research, a journal of the American Association for Cancer Research.

The research contributes to a growing body of evidence linking diet and obesity to the risk of developing cancer.

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 tumour-related angiogenesis, and 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.

The trial enrolled 439 healthy women (no 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, and a control arm with no intervention.

They 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 tumours, they believe there could be an association between reduced protein levels and a less favourable environment for tumour growth.

Source: Cancer Research