Breast cancer News: Breast density and EGFR may predict risk

Breast density linked to breast cancer risk

A decrease in breast density as shown on the mammogram images over a number of years may indicate a reduced risk of breast cancer, according to Mayo clinic Campus in Minnesota researchers.

The researchers said that a decrease in breast density as seen from two different mammograms taken an average of six years apart was associated with a 28 percent reduced risk of developing breast cancer compared to those whose breast density showed not change.

Celine Vachon, Ph.D. and colleagues presented their findings at the American Association for Cancer Research (AACR) 101st Annual Meeting 2010.

Breast density is a known risk factor for breast cancer.  But the new study was meant to improve the current assessment employed in most clinical settings known as BI-RADS, breast imaging reporting and data system, which is not sophisticated enough for measuring breast density.

Dr. Vachon said "There is a lot of ongoing work aimed at improving measures of density, so that situation should change."

The study was based on data from 19,924 cancer-free women who participated in the Mammography Health Study. The participants residing in Minnesota, Iowa and Wisconsin were offered screening mammograms at Mayo clinic between 2003 and 2006.

Two measures of mammography breast density were obtained from two mammograms taken six years apart for 1,900 women randomly sampled from the study group and all 219 women who were diagnosed with breast cancer during the follow-up.

The researchers found among those who remained free of breast cancer, 38.6 percent of women had a decrease in breast density, 50.4 percent did not change and 11 percent increased their breast density.

In comparison, among those who were diagnosed with the disease, the percentages were 37, 51 and 12 respectively.

A decrease in breast density was more likely to be found in women who did not develop breast cancer.  To be exact, women who decreased one BI-RADs category or more over the six years were at 28 percent reduced the risk compared to women who did not change their breast density.

"We know that breast density can change with time, as evidenced by decreases seen with women going through menopause or using the breast cancer preventive drug tamoxifen and increases seen with postmenopausal hormone therapy use. Our results suggest that decreases in density may translate to decreased breast cancer risk," Dr. Vachon said.

Increased EGFR levels may be an early marker of breast cancer

Levels of epidermal growth factor receptor (EGFR) were found elevated in the blood of women within 17 months prior to their breast cancer diagnosis, according to findings presented at the American Association for Cancer Research 101st Annual Meeting 2010.

Christopher Li, M.D., Ph.D., at the Fred Hutchinson Cancer Research Center, Seattle, said the findings may lead to an early detection of breast cancer.

Currently mammogram screening is recommended for early diagnosis of breast cancer, but a debate is ongoing over the effectiveness and safety of this screening method.

Dr. Li and colleagues analysed blood drawn within 17 months prior to diagnosis from 420 estrogen receptor-positive breast cancer patients and found the association.

The researchers also validated the biomarkers in a similar set of 198 cases and controls from the Women's Health Initiative database and found one promising marker was EGFR.

They found overall EGFR was significantly increased in breast cancer patients compared to controls.  Those who had the highest levels were 2.9 times as likely as those who had lowest levels to be diagnosed with breast cancer.

The association was particularly significant among those who received estrogen plus progestin hormone therapy. These patients were at a 9-fold increased risk of breast cancer. 

Hormone therapy has been associated with increased risk of breast cancer.  This is understandable because hormone is known to promote cancer cell growth.

Among the hormone users, EGFR had a specificity or the rate of true negative tests, of 90 percent and a sensitivity or the rate of true positive tests, of 31 percent as a breast cancer marker.

Li acknowledged that more research is needed to confirm the findings.

Still, Li said "Our results suggest that there may indeed be detectable changes of proteins in blood within two years of making a clinical breast cancer diagnosis. Identification of these proteins could have a major impact on our ability to detect breast cancer early, when it is most treatable."

According to a press release, increased EGFR activity can increase cancer growth and EGFR was found elevated in 20 to 81 percent of all human breast cancers.

JD