Cancer Patients with Dense Breasts Face Greater Risk of Disease Recurrence

Women who have dense breasts, and undergo lumpectomies for the treatment of breast cancer, are at a greater risk of a recurrence of the disease. In fact, breast cancer patients with more dense breasts are four times as likely to have their cancer return than women with less dense breasts.

The new information comes from research performed by Steven A. Narod, M.D., of the Women's College Hospital in Toronto, and colleagues. According to Dr Narod, “The composition of the breast tissue surrounding the breast cancer is important in predicting whether or not a breast cancer will return after surgery.” The study report can be found in the journal Cancer.

The researchers analyzed data on 335 breast cancer patients having an average age of 63.5 years, who had undergone lumpectomies for the removal of cancerous tumors from their breasts. Findings revealed that for women having more dense breasts, the risk of the cancer recurring over 10 years was more than four times higher at 21 percent than the 5 percent average. In addition, women who did not receive radiation as part of their initial treatment faced an even higher risk (40 percent) of a tumor recurrence that puts them at an 8 times greater likelihood of developing the disease again.

With the use of mammography, about one in three of the women in the study were found to have large amounts of dense tissue in their breasts. Breast density was discovered to be higher among the younger women in the study, and these women were less likely to be postmenopausal than the others. Of the total number of women in the study, 99 had low-density breasts with dense tissue in less than 25 percent of the breast, 107 had intermediate density in 25 percent to 50 percent of the breast, while 129 women had high-density breasts with more than 50 percent density.

Although it is not known why the density of a woman’s breast has an impact on the risk of developing cancer, it is known that high breast density can reduce the sensitivity of a mammogram by causing a masking effect. In addition, it is the belief of the researchers that the hormonal profile of denser breast tissue makes it more susceptible to cancer. Although Dr Narod noted that breast density has been found to be modifiable to some extent by physical activity and hormone therapy, the researchers cautioned that it is not clear whether these measures would impact the risk of breast cancer recurrence.

Due to this significant increase in risk for cancer recurrence, the researchers maintain that women having more dense breasts should undergo additional treatment after surgery to decrease the chances of the cancer returning. On the other hand, since radiation therapy appeared to eliminate the increased risk for cancer recurrence, they also acknowledged that the findings are an indication that women with low-density breasts may be able to safely avoid radiation. However, they also cautioned that because the study was small, further research will be necessary determine if this is the case.

According to The American Cancer Society an estimated 192,370 new cases of invasive breast cancer will be diagnosed in 2009, and of these 40,170 lives will be lost. Breast cancer is the most common cancer among women in the United States, other than skin cancer. It is also the second leading cause of cancer death among women, after lung cancer. About 1 in 8 women will develop breast cancer at some time during life, and about 1 in 35 will lose the battle against the disease.

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