Breast cancer more likely to return to women with dense breasts

Canadian researchers conducted a study and found women with dense breasts treated for breast cancer were four times more likely to have cancer recurrence than those with less dense breasts, BBC News reported. 

The finding suggests that women with the densest breasts should have radiotherapy while those with less dense breast may not have to.  But further research is needed before any change in treatment. 

The researchers from the Women's College Hospital in Toronto, Canada examined the medical records of 335 women who underwent pretreatment mammogram screening and later surgery for invasive breast cancer. 

They found that over a 10-year period, 21 percent of women with highly dense breasts had cancer recurrence compared to a 5 percent of those who had the least dense breasts.

After 10 years, among the women who did not receive radiotherapy, those with high density breasts had a 40 percent risk of cancer recurrence compared to none of the women with the lowest density of breasts.

It is unknown whether breast density is a sign or a risk factor.  Women at young ages tend to have dense breasts and women diagnosed with breast cancer at young ages tend to have aggressive malignancy.

Susan M. Gapstur and colleagues at Northwestern University reported a study in the Oct 1, 2003 issue of Cancer Epidemiology, Biomarkers & Prevention saying that breast density was strongly and inversely associated with age, body mass index, and menopausal status, and positively associated with hormone replacement therapy use and cigarette smoking.” 

Does this mean that obese women or women with high body mass index are at low risk for breast cancer because of their less dense breasts?   We have known that obesity is linked to higher risk of breast cancer. 

Breast cancer will be diagnosed in more than 170,000 women in the United States and kill about 50,000 women in 2009, according to the National Cancer Institute.   

By David Liu