Low risk of contralateral breast cancer in women with DCIS
By Megan Brooks
NEW YORK (Reuters Health) - The risk of contralateral breast cancer in women with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery is low and does not justify bilateral mastectomy, as an increasing number of women are choosing, researchers say.
In their large study of DCIS patients who underwent lumpectomy, only about 3% developed contralateral cancer after five years and about 6% did so after 10 years.
“A rapidly growing number of women are choosing double mastectomies for DCIS, perhaps because they misperceive their risk of future cancer. Our research provides important data for treatment decision-making,” Dr. Megan Miller, a breast surgical oncology fellow at Memorial Sloan Kettering Cancer Center in New York City, said in a news release.
“It suggests patients and their doctors should focus on risk factors and appropriate therapy for the diseased breast, not the opposite breast, and that ipsilateral DCIS should not prompt a bilateral mastectomy,” said Dr. Miller.
She presented her research April 27 at the American Society of Breast Surgeons (ASBrS) annual meeting.
Among 2,759 women with DCIS who had lumpectomy between 1978 and 2011 and were followed for a median of nearly seven years, the cumulative incidence of ipsilateral breast tumor recurrence (IBTR) was 7.8% at five years and 14.5% at 10 years, compared with 3.2% and 6.4% for contralateral cancer, respectively.
Endocrine therapy was the only factor that impacted contralateral cancer. At 10 years after surgery, women who received tamoxifen or aromatase inhibitors had about half the risk of developing contralateral breast cancer as those who did not. “That’s not surprising because these are systemic therapies and will affect both breasts equally,” Dr. Miller noted in the release.
IBTR was more common in women younger than 40 and in those presenting with clinical findings, including a palpable mass, nipple discharge and Paget’s disease, relative to those with screen-detected cancer. IBTR was less common in women who received post-surgical radiation and those treated more recently (after 1999), presumably because treatments have improved, Dr. Miller noted.
Summarizing her findings at a conference press briefing, Dr. Miller said the results suggest a “low risk of contralateral breast cancer after DCIS for women treated with breast-conserving surgery, irrespective of age, family history and characteristics of the initial DCIS. Importantly, contralateral risk is not higher after ipsilateral recurrence. Factors associated with ipsilateral recurrence are not associated with any contralateral cancer, including invasive disease.”
“While factors associated with ipsilateral recurrence risk are important in decision-making regarding management of the initial DCIS, they are not an indication for contralateral prophylactic mastectomy,” Dr. Miller said.
These findings suggest that bilateral mastectomy in the setting of unilateral DCIS “should be the exception rather than the routine,” Dr. Julie Margenthaler, a breast surgeon at Washington University School of Medicine and communications chair of the ASBrS, said in the news release.
The ASBrS recently published a consensus statement recommending against routine contralateral prophylactic mastectomy for average risk women with unilateral breast cancer. http://bit.ly/2oYqNNT
American Society of Breast Surgeons 2017.
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