Bilateral Surgery May Boost Hereditary Breast Cancer Survival

Prophylactic contralateral mastectomy may reduce the risk of dying for women with BRCA-positive breast cancer

medwireNews: A review of women with BRCA-associated breast cancer suggests that bilateral mastectomy may improve survival over ipsilateral surgery.

As reported in BMJ, the 20-year survival rate for the 181 women with stage I or II breast cancer and a BRCA1 or BRCA2 mutation who chose to have their contralateral breast removed was 88%, compared with just 66% for the 209 women who underwent mastectomy only in the affected breast.

After adjusting for prognostic factors, such as age at diagnosis, tumour characteristics, treatment and oophorectomy, bilateral mastectomy was associated with a 48% reduction in the likelihood of a patient dying from breast cancer compared with ipsilateral surgery.

The women were followed-up at 12 clinics for an average of 14.3 years and analysis of the second decade gave an 80% reduction in the risk of breast cancer death, report Steven Narod, from the Women’s College Research Institute in Toronto, Ontario, Canada, and co-authors.

However, the association between survival and contralateral mastectomy was no longer significant when assessed using propensity score adjusted analysis for 79 matched patient pairs, and there was no correlation between surgical procedure and breast cancer survival for the first 10 years after mastectomy.

The researchers note that just 12% of the patients in the study had immediate bilateral mastectomy, with 40% choosing contralateral surgery at a later date, perhaps due to a delay in finding out their mutation status.

The majority of deaths occurred in the second decade of the study and in women who developed a second primary breast cancer an average of 5.7 years after initial diagnosis, “therefore, a delay in the observed benefit of contralateral mastectomy is to be expected,” the researchers explain.

Steven Narod and co-workers conclude that bilateral mastectomy should be considered an option for young women with early BRCA-associated breast cancer but that further research is required to confirm the benefits.

They add: “In the future, if genetic testing is performed routinely at the time of diagnosis, comparisons of the various surgical treatments will become more straightforward, although long term follow-up data will not be available for decades.”

In an accompanying editorial, Karin Michels, from Brigham and Women’s Hospital in Boston, Massachusetts, USA, writes that the decision to undergo bilateral mastectomy will remain a difficult and personal choice for a woman even after any benefits are confirmed.

“A woman needs to weigh up alternative options, including regular close monitoring and the use of tamoxifen or raloxifene, while considering the opportunities but also possible complications of reconstructive surgery,” she states.

“No statistics and no statistician can make this decision for her.”

References

Metcalfe K, Gershman S, Ghadirian P, et al. Contralateral mastectomy and survival after breast cancer in carriers of BRCA1 and BRCA2 mutations: retrospective analysis. BMJ 2014; 348: g226
Michels KB. Contralateral mastectomy for women with hereditary breast cancer. BMJ 2014; 348 :g1379

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