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The Daily Express on May 29th 2002 (1) reports that for women at high risk of developing cancer, removing the ovaries and fallopian tubes can significantly reduce the risk of breast and ovarian cancer. The newspaper article accurately reports the research (2), but does not mention the potential risks associated with the surgical intervention.
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The newspaper article reports that women who are at high risk of developing cancer should consider having their ovaries removed soon after they have finished childbearing to reduce their risk of developing breast and ovarian cancer.
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The newspaper article is based on the findings of a prospective cohort study that followed up 170 women 35 years of age or older and who are carriers of the BRCA1 or BRCA2 gene mutations for a period of two years. Women chose to undergo salpingo-oophorectomy (removal of the fallopian tube and ovary) or routine surveillance. Salpingo-oophorectomy was found to significantly reduce the risk of the combined incidence of hereditary breast and gynaecological cancer.
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The newspaper article is accurate in it's reporting of the research paper. However, the article does not explain that not all women who carry the gene mutations go on to develop cancer and gives no indication of the risks associated with the surgical intervention. The research study also fails to adequately investigate the potential risks associated with salpingo-oophorectomy (e.g. increased risk of osteoporosis and cardiovascular events). The newspaper also fails to mention that salpingo-oophorectomy may be ineffective against peritoneal cancer.
Evaluation of the evidence base for salpingo-oophorectomy reducing the risk of breast and ovarian cancer.
Where does the evidence come from?
The research was conducted by Noah Kauff and colleagues at the Memorial Sloan-Kettering Centre in New York. It was supported by grants from the American Cancer Society, a grant form the Department of Defense Breast Cancer Research Program, the Society of Memorial Sloan-Kettering Cancer Centre, the Koodish Fellowship Fund, the Lymphoma Foundation, the Danziger Foundation, the Frankel Foundation, and the Breast Cancer Research foundation. A total of 170 women 35 years of age or older who were carriers of the gene mutations BRCA1 and BRCA2 participated.
What were the authors' objectives?
To evaluate the role of salpingo-oophorectomy in reducing the risk of breast cancer and BRCA-related gynaecological cancers in carriers of BRCA1 and BRCA2 mutations.
What was the nature of the evidence?
Prospective cohort study.
What were the factors of interest?
All women with a BRCA1 or BRCA2 mutations identified during a six-year period were offered enrolment in the prospective follow-up study. Participants were given the choice of undergoing a risk-reducing bilateral salpingo-oophorectomy (with or without a concomitant hysterectomy) or routine surveillance for ovarian cancer. Surveillance included annual or twice-yearly gynecologic examinations, twice-yearly transvaginal ultrasound, and twice-yearly determination of the serum CA-125 concentration. All women who had not undergone bilateral mastectomies were also advised to undergo annual mammographic examinations, to have clinical breast examinations two to four times per year, and to perform breast self-examinations monthly.
What were the findings?
The mean follow-up was 24.4 months. Of the 98 women who underwent the risk-reducing salpingo-oophorectomy, three had early-stage tumours that were diagnosed at the time of surgery (3.1%) and one woman developed peritoneal cancer (1.0%) during follow-up. Among the 72 women who chose surveillance, ovarian cancer was diagnosed in four women (5.6%), and peritoneal cancer in one (1.4%). Among women who had not undergone risk-reducing bilateral mastectomy, breast cancer developed in eight of the 62 women in the surveillance group (12.9%) and three of the 69 women in the salpingo-oophorectomy group (4.3%).
The risk of developing either breast or BRCA-related gynaecologic cancer was statistically significantly reduced by 75% in the salpingo-oophorectomy treated group when compared to surveillance alone. The associated risk reduction became 63% (but still statistically significant) when excluding three participants who were found to have early stage cancer at the time of surgery.
What were the authors' conclusions?
Salpingo-oophorectomy in carriers of BRCA muations can decrease the risk of breast cancer and BRCA-related gynaecological cancer.
How reliable are the conclusions?
This was a reasonably well-conducted study that used an appropriate study design (prospective cohort) to evaluate the proposed research question. One of the limitations of this kind of study design is the possibility of selection bias. Women who were in the Salpingo-oophorectomy treatment group were more likely to have had bilateral mastectomy than those in the surveillance group. They may also have been more likely to have taken other precautions to try and reduce their risk of developing cancer. There was no significant difference between the two groups for any of the other participant characteristics reported.
The follow-up period of two-years was fairly short and the findings were based on a small number of participants. As the authors themselves state, one of the limitations of the study was that they only looked at time to cancer and not overall survival. Salpingo-oophorectomy in premenopausal women may lead to an increase risk of cardiovascular disease and osteoporosis, as well as other adverse events. The actual surgical procedure itself also carries an associated risk, although the authors do report on serious surgical complications that were noted in four included participants. A larger study, using longer follow-up, taking into account overall survival as well as other adverse events would provide better information to enable women to choose the right option for reducing the risk of hereditary breast or gynaecological cancer.
[National electronic Library for Health]
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Last Revised at December 10, 2007 by Lusine Kazoyan, M.D.
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