Ovary removal is linked to lower breast cancer mortality in BRCA1 carriersBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h2182 (Published 24 April 2015) Cite this as: BMJ 2015;350:h2182
Removal of the ovaries is associated with a 62% reduction in breast cancer deaths among women with diagnosed breast cancer who carry the BRCA1 mutation, a retrospective analysis published in JAMA Oncology has found.1
Women who carry a mutation in either the BRCA1 or BRCA2 gene have a lifetime risk of breast cancer of up to 70%, and once they have a diagnosis of breast cancer they face high risks of second primary breast and ovarian cancers. Preventive oophorectomy is recommended to women aged over 35 with a BRCA mutation to prevent breast and ovarian cancer, but it is unclear whether removing the ovaries may also reduce mortality from breast cancer.
Of 676 women with stage I and II breast cancer who had a BRCA1 or BRCA2 mutation, 345 underwent bilateral oophorectomy after the diagnosis of breast cancer and 331 retained both ovaries. The patients received a diagnosis between 1977 and 2009 and were observed for an average 12.5 years (range 0.7 to 20.0 years). A total of 128 participants (18.9%) died during this time. The mean time to death was 7.8 years after diagnosis.
Removal of ovaries was associated with a significant reduction in breast cancer death in women with a BRCA1 mutation (adjusted hazard ratio 0.38 (95% confidence interval 0.19 to 0.77); P=0.007). There was a 43% reduction in women with a BRCA2 mutation, but this was not statistically significant. In the entire group oophorectomy was particularly effective for survival benefit in women with oestrogen receptor negative breast cancer (hazard ratio 0.07 (0.01 to 0.51); P=0.009).
In addition, nine women who hadn’t undergone oophorectomy died from ovarian cancer. The adjusted analysis showed a 65% reduction in all cause mortality associated with oophorectomy.
The oophorectomies were carried out an average of six years after the diagnosis of breast cancer. Among the 70 BRCA1 carriers in whom ovary removal was carried out within two years of their diagnosis of breast cancer there was a 73% reduction in death in comparison with women who did not have an oophorectomy (hazard ratio 0.27 (0.11 to 0.66); P=0.004).
The Canadian authors acknowledged that the study’s limitations included that it was a non-randomised historical cohort study of patients enrolled since 1975 and reflected treatments that were in use at the time of diagnosis. The cancers were predominantly clinically detected, whereas survival may have been better in patients whose diagnosis resulted from magnetic resonance imaging surveillance. Also, the study included only women with stage I and II breast cancer, and so the results may not apply to more advanced stages of cancer.
However, they concluded that when women with a BRCA1 or BRCA2 mutation receive a new diagnosis of breast cancer, removal of their ovaries should be offered as a component of their treatment plan. They also recommended that the operation be performed in the first year of treatment to maximise the benefit.
Cite this as: BMJ 2015;350:h2182