23 March 2017
Article by Sarah Hatherley, National Assembly for Wales Research Service
Ovarian cancer is often described as ‘the silent killer’ because symptoms are not well-known or often mistaken, meaning the condition is usually discovered in the late stages when successful treatment is much more difficult.
Ovarian cancer is the fourth most common cause of cancer death for women in Wales, with 238 deaths in 2014.
The National Assembly’s Petitions Committee considered a petition submitted by retired palliative care nurse, Margaret Hutcheson who called on the Welsh Government to support yearly screening for ovarian cancer. The petition gathered 104 signatures online. On 9 February 2017, the Petitions Committee published its report. Assembly Members will debate the report in plenary on 27 March 2017.
The Committee’s report
Whilst the Committee did not support the petitioners’ ambition for a national screening programme using the CA125 blood test, they did agree on the importance of early detection, recognising the significance of diagnosing ovarian cancer at the earliest stage. The Committee heard that unfortunately many ovarian cancers are diagnosed at the late stage, meaning that many women will not be treated until it is too late, when their treatment options may be more limited. The Committee said they wanted to see improved screening to permit early diagnosis of ovarian cancer but concluded, that at the moment, there is no screening test reliable enough to use for ovarian cancer:
The Committee took evidence on the effectiveness of the CA125 blood test, and on other potential detection methods, but concluded that there simply is not currently the weight of evidence to conclusively prove that lives would be saved by introducing an annual screening programme. However, they recommended that the potential for such a programme should be kept under review.
There are various trials looking at ways to prevent and detect ovarian cancer earlier.
Cancer screening involves testing apparently healthy people for signs that could show that a cancer is developing. Current cancer population screening in the UK includes breast, cervix and bowel cancer screens. In order for a screening test to be made available on the NHS, the test has to be proven to be accurate and safe. There are ongoing studies to find a general population screening test for ovarian cancer but until their work is completed, ovarian cancer screening will not be available in Wales, or any part of the UK. The Welsh Government has made clear that it would not introduce an ovarian cancer screening programme unless it is recommended by the UK National Screening Committee, who provide independent, expert advice to all UK Ministers about screening.
The CA125 blood test
CA125 is known as a tumour marker for ovarian cancer. A tumour marker is a chemical given off by cancer cells that circulates in the bloodstream. Women with ovarian cancer tend to have higher levels of CA125 in their blood than women who do not have ovarian cancer. But CA125 can also be raised for other non-cancerous reasons. So the test is not completely reliable. The CA125 blood test can detect ovarian cancer, but research has shown that it is not accurate enough to be used as part of a screening programme because positive results could also be due to other conditions.
UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS)
The UKCTOCS trial, which commenced in 2001, involved 200,000 women aged 50-74 years. It is a randomised trial in which women taking part are allocated randomly for screening with either CA125 or ultrasound, or to a control group who are followed up without screening. The results of the UKCTOCS trial were published in December 2015. They indicated that screening based on an annual blood test may help reduce the number of women dying from ovarian cancer by around 20 per cent. The result was similar for women who received an ultrasound. However, the results included a large ‘confidence interval’ – effectively the size of the uncertainty in the result. This was due to the low numbers of women who have so far developed and died from ovarian cancer in the trial – about 650 out of 200,000 – and means that the range of possible benefit could be anywhere between 0 and 40 per cent. Therefore, the study concluded that longer follow-up is needed to establish more certain estimates of how many deaths from ovarian cancer could be prevented by screening. As a result it will continue to run for another 3 years.
While the Committee concluded that it could not recommend that annual ovarian cancer screening be introduced, it did make 3 recommendations:
- That the potential for a national screening programme be kept under review by the Welsh Government;
- That more work should be done with GPs to ensure that women who present with symptoms of ovarian cancer are referred for appropriate tests; and
- More should be done to improve awareness of ovarian cancer including identifying common symptoms and advising when people should seek medical help.
Better ways to screen for ovarian cancer are being researched. Hopefully, improvements in screening tests will eventually lead to a lower ovarian cancer death rate.