Soy isoflavones may modify risk of breast cancer

Increased phytoestrogens commonly found in dietary soy may modify the risk of some types of breast cancer, according to findings presented at the Ninth Annual AACR Frontiers in Cancer Prevention Research Conference, held Nov. 7-10, 2010.

"This study was unique in that we looked at specific subtypes of breast cancer, and found a suggestion that menopausal status may play a role in risk," said Anne Weaver, a graduate student at the University at Buffalo and research apprentice at Roswell Park Cancer Institute.

Weaver and colleagues evaluated 683 women with breast cancer and compared them with 611 healthy women. Dietary data patterns were observed using a food frequency questionnaire and isoflavones were measured as a dietary, rather than supplemental, intake. Isoflavone intake was divided into three groups.

Those women with the highest isoflavone intake had an approximately 30 percent decreased risk of having an invasive breast tumor, and an approximately 60 percent decreased risk of having a grade 1 tumor.

Observations by menopausal status revealed the following: Among premenopausal women, the highest intake of isoflavones had a 30 percent decreased risk of stage I disease, a 70 percent decreased risk of having a tumor larger than 2 cm, and a 60 percent decreased risk of having stage 2 breast cancer. These connections were not seen among postmenopausal women.

Like most dietary studies, Weaver said these findings are not definitive and need to be considered in the context of further follow-up and confirmation.

"Still, we definitely saw a reduction that deserves further investigation," she said.

###

Download interviews with cancer researchers and recordings of teleconferences by subscribing to the AACR Scientific Podcasts via iTunes (http://www.aacr.org/itunes) or an RSS Reader (http://www.aacr.org/rss).

The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, the AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes 32,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants, research fellowships and career development awards. The AACR Annual Meeting attracts more than 18,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. Including Cancer Discovery, the AACR publishes seven major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. AACR journals represented 20 percent of the market share of total citations in 2009. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists.