Western Regional Blog – BC, YK, AB, NWT and Nunavut
Full article: J Clin Oncol. 2014 Feb 24. [Epub ahead of print].
An epidemiologic study of 5783 women with BRCA1 or BRCA2 mutations demonstrated that preventive bilateral oophorectomy reduced the risk of ovarian, fallopian tube, or peritoneal cancer by 80% and reduced all-cause mortality by 77%.
In this global study, women with either BRCA1 (n = 4473) or BRCA2 (n = 1310) mutations were asked to complete questionnaires about their reproductive history, surgical history (including preventive oophorectomy and mastectomy), and hormone use. Among the 5783 women, 2270 did not have an oophorectomy, 2123 had an oophorectomy before the study began, and 1390 underwent oophorectomy during the study follow-up period. Mean age at study entry was 46 years.
After an average follow-up of 5.6 years, 186 women developed either ovarian (n = 132), fallopian (n = 22), or peritoneal (n = 32) cancer, of whom 68 have died. Among women with intact ovaries, 108 were diagnosed clinically, including 98 with a BRCA1 mutation (annual rate, 0.91%) and 10 with a BCRA2 mutation (annual rate, 0.30%). In addition, 46 women had an occult cancer diagnosed at the time of oophorectomy, and 32 women developed peritoneal cancer after oophorectomy.
Based on this large cohort, the authors were able to estimate the annual risk of cancer in carriers with intact ovaries by age group and provide guidance on the relative cancer risk depending on the age at oophorectomy. Women with a BRCA1 or BRCA2 mutation were at highest risk in their 50s or 60s, respectively. Study results indicate if a woman with a BRCA1 mutation delays prophylactic surgery until age 40 years, her risk of ovarian cancer is raised to 4.0%. The risk of developing ovarian cancer increases to 14.2% if a woman with a BRCA1 mutation waits until age 50 years. Bilateral oophorectomy reduced that risk by 80% (hazard ratio [HR] = 0.20; P<.001). Additionally bilateral oophorectomy also reduced the risk of all-cause mortality to age 70 years by 77% (HR = 0.23; P<.001). Such a profound survival benefit has not been seen before. Previous studies have shown that oophorectomy also reduces the risk of breast cancer by 48% in women with a BRCA1 mutation.
In a report on this study, CNN quoted Steven Narod, MD (University of Toronto, Ontario, Canada), senior author on the paper, as saying that “These data are so striking that we believe prophylactic oophorectomy by age 35 should become a universal standard for women with BRCA1 mutations.”