Researchers from the US have developed a risk score that could be used to quantify women’s risk of ovarian cancer and determine which patients should be offered prophylactic oophorectomy at the time of hysterectomy.

A total of 1,098 women who developed invasive ovarian cancer were compared with 1,363 controls aged > 40 with no history or family history of breast or ovarian cancer. All completed a questionnaire.

Several factors emerged as conferring higher risk of developing ovarian cancer. These were were: polycystic ovary syndrome or obesity, Jewish ethnicity, habitual application of talc to the genital area, dysmenorrhoea or endometriosis, less than one year’s use of oral combined contraception, no tubal ligation, no breast feeding and nulliparity. All factors were statistically significant. These key risk factors were used to develop a risk score.

The score was assessed in 126 cases and 156 controls who had previous hysterectomy to determine whether risk factors or reasons for the surgery could have distinguished women who developed ovarian cancer.

The lifetime risk (i.e. by age 85) of developing ovarian cancer increased with the number of risk factors and decreased with age.

So for a 40-year-old woman with one risk factor or none the lifetime risk was 1.2%. This dropped steadily to 1% at 60 years and 0.5% at age 75. The respective figures for a woman with three risk factors were 3.2, 2.6 and 1.3%. For women with five or more risk factors it was 6.6% at 40 years, 5.3% at 60 and 2.6% at 75.

The authors stress that their risk assessment tool should be validated in other data sets.

Ovarian cancer has a better prognosis if caught early, unfortunately, it almost always presents at an advanced stage. Prophylactic removal of ovaries at the time of hysterectomy is one way to avoid the risk of future cancer but it has a small adverse effect on cardiovascular and bone health. This study suggests that it may be possible to identify women at greater risk of future ovarian cancer who may be especially advised to have prophylactic oophorectomy.

It is common practice to discuss prophylactic oopherectomy before hysterectomy in peri- and postmenopausal women. These figures suggest that a more refined approach may be possible. Sharing actual percentage risk figures may help women and their gynaecologists make a more informed choice.

Dr Chris Barclay