Women with dense breasts have at least four times the risk of breast cancer compared to those with mostly fatty breasts. They also have a greater risk of a second primary breast cancer (a new tumor that arises after treatment and that does not appear to be directly related to the first breast cancer) if they do develop breast cancer. However, radiation treatment significantly reduces the risk of local recurrence among breast cancer patients with dense breasts who receive a lumpectomy.

Women who undergo lumpectomy or partial mastectomy should have radiotherapy as part of their treatment to kill any remaining tumor cells in the breast. Approximately one in four local recurrences eventually will lead to stage IV disease and death. Radiation significantly reduces the risk of locoregional recurrence (recurrence in the breast, chest wall, or lymph nodes), which in turn reduces the risk of distant metastasis. This appears to be especially important for women with dense breasts. One study found that 40% of women with high breast density who did not receive radiation treatment experienced local breast cancer recurrence by the 10-year mark. Now a new study has reported that radiation treatment improves survival in women with dense breasts.

Latest research finds radiotherapy improves prognosis

The study referenced at the beginning of this news article was designed to investigate the influence of prediagnostic breast density on breast cancer survival. The study included 607 women within the Hawaii component of the Multiethnic Cohort (MEC) who had been diagnosed with breast cancer (approximately 21% in situ, 63% localized, and 16% regional/distant stage). The women, who were at least 50 years old at baseline and enrolled in a mammographic density case-control study, were followed for a median of 12.9 years. The Hawaii Tumor Registry was used to obtain tumor characteristics and vital status.

A total of 27 of the women died from breast cancer and 100 died from other causes during follow up. In addition, 71 new primary breast tumors were diagnosed. When all of the women were considered together, mammographic density did not appear to be associated with breast cancer-specific survival. However, when the women were grouped according to whether they had received radiation treatment, percent breast density was found to be associated with a reduced risk of dying from breast cancer in women who had received radiation, but with an elevated risk in patients who had not received radiation. In other words, radiation treatment improved prognosis in women with dense breasts. High breast density also was associated with a borderline increase in risk of a second primary tumor. The authors conclude that assessing mammographic density in women with breast cancer might identify women with a poorer prognosis whose outcomes could be improved with radiation treatment.

Please see our article on the latest research concerning breast density for more information.