Women with breast cancer and a history of mantle radiation therapy for Hodgkin disease predominantly exhibit cancer occurrence within the upper outer quadrant of the breast, according to a study published in the April issue of Radiology.

Because treatment for Hodgkin disease often requires mediastinal irradiation, chest wall structures including the breast are exposed to radiation. This exposure can lead to the potential for a second malignancy, with a 20-fold increase in risk for breast cancer in women, particularly those who are younger. Lead author Steven D. Allen, FRCR, of the Royal Marsden NHS Foundation Trust in Surrey, England, and colleagues conducted a retrospective study to review diagnostic mammographic imaging in women diagnosed with breast cancer who had previously underwent mantle field radiation therapy for Hodgkin disease.

Of 5,002 women who were treated with mantle field radiation therapy before the age of 36 between 1956 and 2003, 392 patients developed breast cancer. The researchers found that 38 of 230 tumors were occult on mammograms. The average maximum tumor diameter was 12.3 millimeters.

Results indicated that tumors had significantly different quadrant distribution from the study’s historic controls. Chest radiation therapy patients had 66.9 percent of their tumors in the upper outer quadrant, while 48.7 percent of the control group had tumors in that area. Tumors were found in the lower inner quadrants for 10.6 percent of the patients and 7.8 percent of the controls.

The most dominant radiologic feature was an irregular mass, followed by microcalcifications.

“Our study suggests that breast cancers in patients who had previous mantle radiation therapy for Hodgkin disease are more commonly seen within the upper outer quadrants than are cancers in the general population,” wrote Allen and colleagues. “Poorly defined masses appear most commonly in images, which is unusual given the predominance of nonfatty breast density in our cohort,” they concluded.