ASBS: BRCA-Negative Breast Cancer Patients May Have Higher Risk of New Lesions

By Charles Bankhead
NEW YORK, 06 may 2008 -- Women with a history of breast cancer but who are negative for BRCA 1 or BRCA 2 may have a greater risk of occult malignancies than previously believed, a surgeon reported here.Occult breast cancer was found in 11% of breast specimens from women who opted for prophylactic mastectomy after a malignancy was discovered in the contralateral breast, Shawna Willey, M.D., of Georgetown University, said at the American Society of Breast Surgeons meeting.The frequency of occult cancer was about twice as great as previously reported for BRCA 1-2-negative women who have such prophylactic mastectomies. The rate also was higher than for carriers of the BRCA susceptibility gene mutations, who had a bilateral prophylactic mastectomy.
"The higher rate of occult cancers may be because they all had contralateral known malignancies," said Dr. Willey. "Even so, this study supports the use of prophylactic mastectomy as an option for these women, as it is for those who have a BRCA mutation."
Unlike with carriers of BRCA 1-2 mutations, the decision to have the contralateral breast removed for noncarriers with a history of breast cancer is complicated by a lack of data on the risk of a second malignancy, said Dr. Willey. A common estimate is 5%.
To gather additional data on the issue, investigators studied 119 women who had at least a 10% prior probability of BRCA 1-2 mutation. Genetic testing identified 74 women as mutation carriers. The remaining 45 patients had developed breast cancer but their genetic testing results were uninformative.
The BRCA mutation carriers had bilateral prophylactic mastectomy. Those with uninformative genetic results underwent prophylactic removal of the contralateral breast.
Pathologic assessment of breast specimens revealed atypical histopathology in 12.6% of specimens from the BRCA mutation carriers and 26.7% of specimens from the noncarriers (P=0.04).
"The higher rate of atypical histopathology in women with uninformative results may be due to selection bias because this population of women all had contralateral known malignancies," said Dr. Willey.
Pathologic examination also showed that 7.4% of specimens from BRCA-positive patients had occult malignancies compared with 11.1% of specimens from women who had uninformative test results. Four of seven (57.1%) occult malignancies were invasive in the BRCA carrier group versus two of five (40%) in the women with uninformative test results.
"The trend in this study highlights the importance of counseling all high-risk women about their risk of developing another cancer when considering surgical options," said Dr. Willey.
Dr. Willey reported no disclosures.
Primary source: American Society of Breast SurgeonsSource reference:Feldman E, et al "The incidence of occult malignancy and atypical histopathology in prophylactic mastectomy specimens after uninformative BRCA testing" ASBS Meeting 2008.