Increased breast density predicted local disease recurrence after breast-conserving surgery

Mammographic breast density may predict local breast cancer recurrence in women who have undergone breast conserving surgery but not breast irradiation, according to data published online first in Cancer.

Researchers reviewed the medical records of 335 women who underwent breast-conserving surgery for invasive breast cancer. Using pretreatment mammograms they categorized mammographic density according to Wolfe classification: low density (<25%; n=99), intermediate density (25% to 50%; n=107) or high density (>50%; n=129). Across groups, a total of 34 patients (9.6%) developed local disease recurrence.

Three percent of women in the low-mammographic density group developed local disease recurrence compared with 10.3% of women in the intermediate-density group and 15.5% of women in the high-density group. The 10-year actuarial risk of local disease recurrence was 5% in the low-density group, 13% in the intermediate-density group and 21% in the high-density group. Controlling for age, menopausal status and adjuvant chemotherapy, researchers found an HR of 5.7 for the development of local disease recurrence for women in the high-density group vs. those in the low-density group (95% CI, 1.6-20.0).

The overall risk for local disease recurrence at 10 years was 22% for those who did not receive radiotherapy compared with 10% for those who did. The differences in disease recurrence based on mammographic density were more pronounced for women who did not receive radiotherapy, with a 40% actuarial risk for women in the high-density category compared with 0% in the low-density category (P<.0001).

The researchers suggested that mammographic density be considered when patients are stratified in clinical trials of partial breast radiotherapy. “If confirmed, mammographic density might be used to help determine which patients might benefit from radiotherapy,” the researchers wrote.

Cil T. Cancer. 2009;doi:10.1002/cncr.24638.