Tracking the Link Between Adolescent Diet and Breast Cancer: Research Continues with 8-Year-Old Girls Who Are Now Young Women

PHILADELPHIA - Reaserchers from around the country are seeking out more than 300 women aged 25 to 29 to continue research started when the women were grade-school girls. The research then and now focuses on establishing what link, if any, exists between the diets of adolescent girls and their future risk of developing breast cancer.

The research conducted in the 90's involved an intervention to modify dietary habits including fat intake of half of the 300 girls, beginning when they were as young as 8 years old to see if their diet affected their sex hormone levels compared to the other girls who ate their usual diets.

The research team led by Fox Chase Cancer Center's Joanne Dorgan, M.P.H., Ph.D., published its first significant findings in 2003 (Journal of the National Cancer Institute, Jan. 15, 2003). Their results showed girls who ate a higher fat diet during puberty had an increased level of sex hormones in their blood. Studies have shown that increased levels of sex hormones can influence the rate of maturation. Early maturation as a girl and elevated serum sex hormone levels as an adult increase a woman's chance of developing breast cancer.

After five years, the girls who ate less fatty foods (as part of the diet intervention group) had a 30 percent lower level of estradiol (the most potent naturally occurring estrogen) in their blood compared to the girls who did not receive diet intervention. After seven years, girls in the intervention group had 50 percent lower progesterone levels. Both hormones impact breast development during puberty.

"Our study showed that even a modest reduction in the consumption of fat during puberty resulted in lower levels of sex hormones such as estrogen and progesterone," explained Dorgan. "Our initial work provided significant insights into the role diet might potentially play in a girl's breast development and future risk of cancer. Beginning this summer, we'll contact these girls who are now young women and ask for their help again. In our follow-up study, we want to find out if their diet also has had an impact on bone and breast density, both factors that are associated with the future risk of breast cancer."

The new research effort, funded by a $4.5 million dollar grant from the National Cancer Institute, aims to evaluate the long-term effects of dietary fat intake during adolescence on breast cancer markers such as levels of hormones in the blood, bone mineral density, and breast density.

In addition to blood samples, researchers will ask the women to have a DXA scan, a test that measures bone density and body composition. Also, the women will be asked to have a breast MRI to measure breast density (mammography is not recommended for young women and breast MRI performs better when breasts are dense as is typical of young women).

"Although we do not know if lower hormone levels during adolescence will influence breast cancer risk in adulthood, adolescence is a time of rapid growth and maturation of the breasts," Dorgan explained. "Estrogens and progesterone contribute to the regulation of this process. By continuing to follow these women, we hope to gain new insights about dietary impact."

Dorgan added, "So often, we hear of people changing their diets late in life to prevent cancer. While that is a good idea, our earlier work suggests having a good diet that begins during childhood and adolescence may be important."

The studies originated as an ancillary to the Dietary Intervention Study in Children (DISC), a multi-center randomized controlled clinical trial to test the safety and efficacy of a cholesterol-lowering dietary intervention in children. DISC was sponsored by the National Heart, Lung and Blood Institute and the National Cancer Institute provided funding for the ancillary study to evaluate the effects of the dietary intervention on hormone levels. The trial was conducted at six DISC clinical centers and coordinating center.

DISC Centers: Children's Hospital, New Orleans, La.; Johns Hopkins University , Baltimore, Md.; Kaiser Permanente Center for Health Research, Portland, Ore.; University of Medicine and Dentistry of New Jersey, Newark, N.J.; Northwestern University Medical School, Chicago, Ill.; and University of Iowa Hospital and Clinics, Iowa City, Ia. Coordinating center: Maryland Medical Research Institute, Baltimore, Md.

Fox Chase Cancer Center was founded in 1904 in Philadelphia, Pa. as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at www.fccc.edu.