An independent US expert group recommends against routine screening for ovarian cancer in women, because their view is the risks outweigh the benefits.

The US Preventive Services Task Force (USPSTF), an independent expert group that makes evidence-based recommendations about clinical preventive services, issued its final recommendation on screening for ovarian cancer on Tuesday.

The recommendation states:

“The USPSTF recommends against screening for ovarian cancer in women (D recommendation).”

The Task Force grades its recommendations according to one of five classifications (A, B, C, D, I) depending on the strength of evidence and size of net benefit (benefits minus harms).

Grade D means the Task Force “recommends against routinely providing [the service] to asymptomatic patients”, and that it found “at least fair evidence that [the service] is ineffective or that harms outweigh benefits”.

The recommendation is published in full in the 11 September issue of Annals of Internal Medicine.

The Task Force concludes there is currently no system of screening for ovarian cancer that is effective in reducing deaths.

The recommendation applies to women who show no signs of the disease and do not carry genetic mutations, such as BRCA1 and BRCA2, that are known to increase their risk of developing it.

“Currently, routine screening for ovarian cancer has no proven benefit and may actually lead to important harms,” Task Force member and chair Virginia Moyer says in a press statement.

A high percentage of women who have the screening receive false-positive results which then leads to them experiencing unnecessary harm, such as undergoing major surgery, she adds.

The Task Force do not take into account the costs of screening: their decision is based purely on assessment of benefits and harms.

The recommendation is in line with screening guidelines of other medical and public health bodies. For instance, neither the American Cancer Society nor the American Congress of Obstetricians and Gynecologists currently recommends ovarian cancer screening for average-risk women with no symptoms.

Moyer says there is “a critical need to develop better screening tests for ovarian cancer”.

Ovarian cancer is an uncommon cancer, accounting for around 3% of all cancers in women. It is hard to detect: many women who develop the disease show no signs or symptoms in the early stages, which unfortunately means it is often diagnosed when treatment is less likely to succeed.

The American Cancer Society estimates that in 2012, about 22,280 women will be diagnosed with ovarian cancer and about 15,500 women will die from the disease. A woman’s risk of getting ovarian cancer during her lifetime is about 1 in 71.

Several tests are used to screen for ovarian cancer, of which the two main ones are transvaginal ultrasound and a blood test for CA-125.

The transvaginal ultrasound test is where a probe is inserted in the vagina to aim sound waves at the organs in the pelvic area. Using the waves, the doctor can “see” the woman’s reproductive organs, including the uterus, ovaries, cervix, and vagina. If something looks abnormal, further tests may be called for, often requiring surgery.

The CA-125 blood test looks for CA-125 protein, a tumor marker can be found in high amounts in women with ovarian cancer. However, a high CA-125 level does not always mean a woman has ovarian cancer. High levels of this substance also can be found in people with many other conditions, including pregnancy and liver problems.

The recommendation re-affirms the Task Force’s 2004 position. In 2008, a review of the literature commissioned by the Task Force that looked at studies published since 2002, concluded there was no new evidence about the benefits of screening for ovarian cancer but found new data about observed harms of screening.

This latest recommendation follows a further “bridge search” to 2011, that focused on evidence from randomized, controlled trials that found three clinical studies: the PLCO Cancer Screening Trial, the UK Collaborative Trial of Ovarian Cancer Screening, and the Shizuoka Cohort Study of Ovarian Cancer Screening.

Following a review of those three trials, the Task Force concludes:

“Of three randomized, controlled trials on ovarian cancer screening published during the search period, only one (PLCO Trial) published results on mortality. Those results are consistent with the current USPSTF guidelines for ovarian cancer screening among asymptomatic, average-risk women.”

However, it also notes that:

“Information from the two other trials may be useful for the USPSTF to consider in the future: SCSOCS has been completed but mortality results have not yet been published, and UKCTOCS is ongoing through the end of 2014.”

Written by Catharine Paddock PhD