Prophylactic Mastectomy in Women With BRCA Gene Mutations Reduces Risk for Breast Cancer to Less Than 1%

Zosia Chustecka

April 16, 2008

April 16, 2008 — Women who carry the BRCA gene mutation have an estimated 85% lifetime risk of developing breast cancer, but a prophylactic mastectomy reduces this risk to less than 1%, Dutch researchers told the 6th European Breast Cancer Conference in Berlin, Germany, today.

Previously, it was thought that the risk was reduced to about 5%, commented lead author Reinie Kaas, MD, from the surgical department of the Netherlands Cancer Institute, in Amsterdam. As a result, there has been some debate about whether women undergoing prophylactic mastectomies should continue with surveillance or not, she explained. She said that the latest results compiled by her team show that continued surveillance is not, in fact, necessary.

Dr. Kaas and colleagues reported a series of 251 women who underwent a uni- or bilateral mastectomy after 1 or more rounds of surveillance. The standard procedure was skin-sparing mastectomy with immediate reconstruction with an implant. About two thirds of these women had the BRCA1 gene mutation (n = 179), and the remainder had the BRCA2 gene mutation (n = 72).

Only 1 of the 251 carriers (0.4%) went on to develop breast cancer, which grew in the incompletely removed axillary tail (part of the breast that extends under the armpit) 2 years after the prophylactic mastectomy. This patient is free of disease 6 years after treatment, the researchers reported.

"Our epidemiologists are investigating how many breast cancers are avoided up to the age of 80 in these women," Dr. Kaas said in a statement. "But on current evidence, we can safely state that continued follow-up, which can be costly and stressful for the patient, is not warranted in patients who have had prophylactic mastectomy."

However, the decision to remove healthy breasts must be made solely by the woman, Dr. Kaas emphasized, and "healthcare services should not press women to make this choice simply to reduce costs."

Currently, about half the women who carry the BRCA gene mutation opt for this measure, she commented. The alternative is ongoing surveillance, which involves monthly breast self-examination, biannual clinical breast examination by a physician, and annual mammography plus breast magnetic resonance imagining (MRI). However, because BRCA carriers are prone to developing fast-growing tumors, even with this surveillance, about 25% to 30% of carriers are diagnosed when the tumor is already more than 2 cm in diameter, she noted.

Intensive Screening is Expensive

The cost of such intensive screening is substantial. Another group of Dutch researchers estimated that screening of such women costs €254 per woman per year, with an extra cost for further investigations of around €61 per woman per year.

Part of the expense comes from the use of MRI, commented Yvonne Kamm, MD, medical oncologist at the Radboud University Nijmegen Medical Center in the Netherlands. "The MRI is expensive in itself, but useful because it can detect very small tumors that might not be picked up otherwise," she said. "It also detects many other abnormalities that are not cancer, and this implies not just extra cost but also considerable anxiety for the women concerned."

In a poster presentation, Dr. Kamm and colleagues outlined the results for 196 women with BRCA gene mutations who had been screened between 1999 and 2005. The women were screened for a median period of 2 years, and in total underwent 1149 breast examinations (of which 2% were abnormal), 494 mammograms (9% abnormal), and 436 MRI scans (14% abnormal). When any abnormality was found, the women underwent further investigation, which led to another 32 breast examinations, 17 mammograms, 64 MRI scans, 114 ultrasound examinations, and 48 biopsies.

During the 6-year period, 13 cancers were found, 11 of which were invasive and 2 of which were in situ ductal carcinoma. "The total costs to find 1 breast cancer were high — €13,168," Dr. Kamm commented.

6th European Breast Cancer Conference (EBCC): Abstracts 18 and 109. Presented April 16, 2008.

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