Pam Harrison

May 01, 2015

Bilateral prophylactic mastectomy (BPM) only becomes more cost-effective than screening with annual mammography alone when a woman's lifetime risk for breast cancer is at least 50%, according to a new modeling study.

The study was presented at the American Society of Breast Surgeons (ASBS) 16th Annual Meeting, in Orlando, Florida.

"Our model suggests that BPM should primarily only be used for women at very substantial risk of breast cancer," Brandy Edwards, MD, from the University of Virginia, in Charlottesville, told a press briefing.

"However, our results should not be the sole criterion for deciding whether or not a therapy is offered or covered by health insurance," she said. "Rather, this should be viewed as a piece of the puzzle that must be complemented by other essential considerations in a larger context relating to the burden of disease and the overall capacity of the healthcare system."

The same modeling study also showed that breast cancer screening using combined mammography and MRI is never more cost-effective than BPM at any level of lifetime risk.

For this calculation, the investigators used a cost of $787 per MRI, determined on the basis of Medicare reimbursement rates.

"The American Cancer Society recommends that women with a lifetime risk greater than 20% to 25% should receive annual screening with both mammography and MRI," Dr Edwards told journalists.

"In our model, combined screening with annual mammography and MRI was the preferred alternative to BPM only when lifetime risk was between 35% and 47% and only when the cost of MRI was at most $80, using a willingness-to-pay threshold of $50,000," she said.

"Even when a willingness-to-pay threshold of $100,000 was used, the estimated lifetime risk of breast cancer still had to be at least 50% for PBM to be cost-effective," she added.

Women included in the cost-effectiveness analysis were at high risk for breast cancer but did not have a known BRCA mutation.

Study Based on Markov Model

For this study, the investigators developed a Markov model in which they evaluated the cost of breast surveillance with either mammography combined with MRI or mammography alone.

In the combined screening strategy, women would undergo both mammography and MRI each year with biannual physician visits, whereas in the mammography-alone strategy, women would be screened with annual mammography and again have biannual physician visits.

The cost of BPM included the cost of both the prophylactic surgery and breast reconstruction.

BPM was assumed to be associated with a 90% risk reduction in breast cancer, as determined on the basis published findings.

The base-case analyses focused on patients starting screening at age 30 years and assumed that a patient's lifetime risk for breast cancer would be met at age 80 years.

Using a willingness-to-pay threshold of $50,000 per life-year, BPM become cost-effective at an estimated lifetime risk of at least 43%, Dr Edwards reported.

"This means that it would cost less than $50,000 for that person to gain 1 additional year of life if their lifetime risk [for breast cancer] was estimated to be at least 43%," she confirmed.

When the willingness-to-pay threshold was increased to $100,000, BPM became cost-effective when that lifetime risk was at least 26%, she added.

However, when the quality-adjusted model was used to calculate cost-effectiveness of BPM, a woman's lifetime risk for breast cancer had to be at least 57% with a willingness-to-pay threshold of $50,000 and at least 50% with a willingness-to-pay threshold of $100,000.

"In women who are at increased risk for breast cancer without a known BRCA mutation or personal history of breast cancer, BPM becomes more cost-effective than annual mammographic screening at an estimated lifetime risk of 50% and therefore should be reserved for women at markedly elevated risk," the researchers concluded.

"Additional screening modalities for use in high-risk women with a lower cost than MRI are needed," they added.

Dr Edwards has reported no relevant financial relationships.

American Society of Breast Surgeons (ASBS) 16th Annual Meeting. Presented April 30, 2015.

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