|July 2011 · Vol. 23, No. 7
EXAMINING THE EVIDENCE
Can a novel risk-scoring systemYES, BUT THE MODEL NEEDS TO BE VALIDATED in other populations and data sets before it can be set to clinical use. For this case-control study of 2,461 women in eastern Massachusetts and New Hampshire, the authors developed a tool to quantify a woman’s risk of ovarian cancer; the tool takes into account the number of risk factors she has. Women who have an above-average score according to this model are more likely to develop ovarian cancer.
for ovarian cancer predict who is
most likely to develop disease?
Women who have a significant family history of breast or ovarian cancer or a documented BRCA mutation should be offered bilateral salpingo-oophorectomy once they have completed childbearing, regardless of the number of other risk factors they have.EXPERT COMMENTARY
William H. Parker, MD
Clinical Professor of Obstetrics and Gynecology, UCLA School of Medicine, Los Angeles, Calif.
The risks and benefits of bilateral oophorectomy at the time of hysterectomy for benign disease are the subject of ongoing discussion. (See, for example, an earlier article on the subject, “Remove the ovaries at hysterectomy? Here’s the lowdown on risks and benefits,” in the February 2010 issue of OBG MANAGEMENT.) There is uniform agreement that women who are at high risk of ovarian and breast cancer because of a significant family history or known BRCA mutation should strongly consider bilateral oophorectomy after completing childbearing. For women at average risk of ovarian or breast cancer, individualization of elective oophorectomy is recommended—but how can you do this for the patient sitting in your office?
Vitonis and colleagues analyzed multiple risk factors associated with ovarian cancer and developed a scoring system to help provide guidance for average-risk women and their physicians who need to make this important decision. This is the kind of mental modeling clinicians do daily in an abstract way, but this scoring system helps frame the associated risks and gives a mathematical value to inform the decision.
Risk factors in the scoring system are:
less than 1 year of oral contraceptive use
no tubal ligation
painful periods or endometriosis
polycystic ovary syndrome or obesity
Subjects who had none or one of these risk factors were calculated to have a 1.2% lifetime risk of ovarian cancer (98.8% will not get ovarian cancer); the risk was 6.6% with a score of 5 or higher (93.4% will not get ovarian cancer).
Risk equation wasn’t fully explored
Noted by the authors, but not studied here, is the other side of this equation: namely, a woman’s risk factors for medical conditions that might be exacerbated by oophorectomy—including bone fracture, neurologic conditions, and, most important, cardiovascular disease. These conditions appear to be more common after oophorectomy and are considerably more prevalent causes of morbidity and mortality among women than is ovarian cancer.
Case-control design is a weakness
Vitonis and colleagues chose exclusion criteria wisely, but the case-control design of the study is a weakness because of inherent recall and selection biases. The authors should be commended for stating calculated risks as absolute risk rather than relative risk, which is usually misunderstood by the media and patients alike.
As the authors point out, their prototype needs to be validated in other populations and data sets, but it begins to frame the decision regarding oophorectomy for women undergoing hysterectomy for benign disease. However, we won’t have the complete picture until the other side of the equation is similarly analyzed—and that side concerns an individual woman’s risks for cardiovascular disease, neurologic conditions, and bone fracture.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Women who have a significant family history of breast or ovarian cancer or a documented BRCA mutation should be offered salpingo-oophorectomy once they have completed childbearing. Women who have an average risk of ovarian cancer should be counseled about risks and benefits as they apply in their particular case. The study by Vitonis and colleagues may be helpful in this regard. The decision to preserve or remove the ovaries and fallopian tubes should be made according to these risk factors and individual preference.—William H. Parker, MD
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