A recent study has shown that regular blood tests performed on 46,237 women aged 50 years or older was “twice as effective as existing methods” at detecting ovarian cancer.
The randomised-controlled trial was carried out by researchers at the University College of London for 14 years. Repeated screenings monitored the levels of CA125 protein (a marker for ovarian cancer). Obtained data was then used in a refined algorithm that was able to accurately predict 86% of cancers and rule out 100% of cancer-free women. This is in contrast to the fixed-cut-off readings of CA125 that have been previously used.
These blood tests represented one arm of current ovarian screening trials, and an equally large contingent of women screened using ultrasound has not yet been reported.
Decisions for the NHS
The NHS does not currently offer any form of regular screening for ovarian cancer for the general public, a disease that is diagnosed in 7,100 women each year in the UK with 4,200 deaths annually.
Speaking to the BBC, Professor Usha Menon, the lead investigator of the study, commented: “Many people would have to be screened so it really needs to be translated to lives saved.” Whether the trial actually reduced mortality in the group has not yet been determined, with results released in the autumn.
Early detection of cancers does not represent a “magic bullet”, careful considerations of misdiagnosis need to be taken into account. A prime example of this is the controversy surrounding prostate cancer tests in men. In 2011, the United States Preventive Services Task Force (USPSTF) recommended against using PSA (marker for prostate cancer) screening for detection of prostate tumours.
Reasons for this withdrawal of support include the inaccuracy of the test itself. It was unable to differentiate between slow-growing non-life-threatening cancers and their aggressive counterparts. False-positives were prevalent, to save one life resulting from PSA screening, 48 men would have to undergo treatment with side-effects including incontinence (loss of bladder control) and impotence. Due to the uneven balance of risk and benefits, the NHS has adopted the same stance on the use of PSA.
The factors governing the benefits and risks associated with medical screenings , like with PSA, need to be carefully assessed before any new ovarian test is to be put in to clinical use.
Several headlines, including from The Guardian and Independent, highlighted the novel method used to detect ovarian cancer. However upon personal investigation, publications as early as 2000 had started to describe using the “new” sampling method for ovarian cancer prognosis. In 2001, a risk-algorithm was performed on consecutive samples from 9,223 women and showed increase in preclinical sensitivity. In 2007, a similarly longitudinal algorithm was able to detect ovarian cancer on average 10 months earlier than the standardised single cut-off procedures established in 1992.
The recent study originating from the University College of London is by no means redundant. It is the first and largest clinical trial for the refined ovarian cancer screening and was able demonstrated its effectiveness. The method used however is not novel; instead, like most popular science stories, it simply solidifies primary research carried out by previous groups.