In a study on 5,783 women with BRCA mutations, women who had ovary removal surgery after 35 were five times more likely to develop ovarian cancer than those who had surgery before 35. They also had a four times higher risk of premature death.
'For women with BRCA1 mutations, these results suggest that surgery should be performed as soon as it is practical', said Dr Don Dizon from the American Society of Clinical Oncology, the organisation whose journal published the study.
The study authors estimate that a BRCA1 carrier who has their ovaries removed after age 40 will have a four percent chance of being diagnosed with cancer. If removal happens after age 50, this rises to 14 percent.
However, BRCA1 carriers who waited until age 40 for ovary removal had a 1.5 percent chance of developing ovarian cancer, which is comparable to the lifetime risk of ovarian cancer in women without a BRCA mutation of 1.4 percent.
In all BRCA mutation carriers, ovary removal reduced the risk of ovarian, fallopian tube or peritoneal cancer by 80 percent and the risk of premature death from any cause by 77 percent.
The study did not show the same effect of earlier ovary removal on BRCA2 mutation carriers. Although they had a decreased risk of cancer after ovary removal, there was no clear increased cancer risk for BCRA2 carriers who delayed ovary removal until after age 40.
Mutations in the genes BRCA1 or 2 increase the risk of breast and ovarian cancers. Surgical removal of breasts (mastectomy) and ovaries (oophorectomy) has long been recommended for BRCA mutation carriers to prevent onset of cancer of these tissues. Removing the ovaries is major surgery, triggers menopause and prevents egg production and pregnancy, so delaying the procedure does have quality-of-life benefits.
Dr Steven Narod of the University of Toronto, who led the study, said, 'These data are so striking that we believe prophylactic oophorectomy by age 35 should become a universal standard for women with BRCA1 mutations'.
'We've always known that the earlier oophorectomy is performed, the greater the protection against both breast and ovarian cancer,' said Dr Noah Kauff, director of ovarian cancer screening and prevention at Memorial Sloan Kettering Cancer Center. 'But you don't fall off a cliff at age 35 or even 40'.