LAS VEGAS (FRONTLINE MEDICAL NEWS) – The risk of ipsilateral breast tumor recurrence was greater than the risk of contralateral breast cancer at both 5 and 10 years following diagnosis of ductal carcinoma in situ (DCIS), investigators report at a press conference in advance of the annual meeting of the American Society of Breast Surgeons.

“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,” said Megan Miller, MD, of Memorial Sloan Kettering Cancer Center. “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.”

In a database review of 2,759 DCIS patients, Dr. Miller and associates found the incidence rate of CBC was 2.8% and 5.6% after 5 and 10 years, respectively, compared with 7.8% and 14.3% for the rate of ipsilateral breast tumor recurrence (IBTR). All patients had undergone breast conserving surgery between 1978-2011, with a median follow up time of 6.8 years.

The investigators also found that CBC did not correlate with age, family history, and initial DCIS characteristics, though these factors did correlate with the risk of IBTR.

Dr. Miller and her colleagues found radiation had no impact on risk of CBC (4.9% vs. 6.3%; P = .1), though it significantly reduced the risk for IBTR (10.3% vs. 19.3%; P less than .0001).

More research is needed on risk factors for patients with a preinvasive condition, Dr. Miller said.

“Most studies examining the benefits of bilateral mastectomy focus on invasive cancer,” she said. “This study is unique in providing hard data for women with preinvasive disease. For these patients, examining risk factors for recurrence and the benefits of radiation and endocrine therapy to treat the existing cancer are important.”

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