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Annual screening for ovarian cancer can detect tumours earlier but does not save lives, one of the largest studies ever conducted on the general population suggests.
Although the finding is a blow to those affected by ovarian cancer, the hope is that earlier diagnosis could reduce the amount and intensity of treatment that women go through.
About 7,500 British women are diagnosed with ovarian cancer each year and 4,000 die from it, making it the deadliest gynaecological cancer. The lack of any single telltale symptom means the disease is often not diagnosed until it is at a late stage – and prompt diagnosis is crucial because although 80-90% of women whose cancer is detected early survive for at least five years, that figure falls to 25% when the disease is spotted late.
© Photograph: Steve Gschmeissner/SPL/Getty Images
Coloured scanning electron micrograph (SEM) of an ovarian cancer cell.
The hope was that screening healthy women for signs of ovarian cancer might improve these survival rates, as population screening for cervical cancer has done.
The study, by researchers at University College London, analysed data from more than 200,000 postmenopausal women, recruited to the trial between 2001 and 2005. Half of the women underwent no screening, while the remainder were either offered a yearly vaginal ultrasound scan, or an annual blood test to detect a cancer-related protein called CA125, followed by an ultrasound scan for those with altered levels of this protein.
The results, published in the medical journal the Lancet, found that although blood test screening picked up 39% more cancers at an early stage (stage I/II), compared with the vaginal ultrasound and no screening groups, this did not translate into a reduction in deaths from the disease.
“Either we need to find more individuals at an earlier stage of disease and fewer individuals with late-stage disease through screening, and/or this disease is such that even if you did that, the biology of [ovarian cancer] means that it’s going to be aggressive whatever you do, even if you find it at an early stage,” said Prof Mahesh Parmar, the director of the Medical Research Council clinical trials unit at UCL and a senior author on the paper.
The researchers did notice that those women identified through the blood test did not respond as well to standard treatment as those women who did not undergo screening but whose cancers were identified early based on their symptoms.
Disappointing as the results are, Parmar emphasised that in women who do have symptoms of ovarian cancer, early diagnosis, combined with significant improvements in the treatment of advanced disease over the past 10 years, could still save many lives.
“Our trial showed that screening was not effective in women who do not have any symptoms of ovarian cancer; in women who do have symptoms, early diagnosis, combined with this better treatment, can still make a difference to quality of life and, potentially, improve outcomes,” he said. “On top of this, getting a diagnosis quickly, whatever the stage of the cancer, is profoundly important to women and their families.”
The team is conducting further analysis to look at whether earlier detection may result in less extensive surgery or chemotherapy.
Athena Lamnisos, the chief executive of the Eve Appeal, which funds research into womb, ovarian, cervical, vulval and vaginal cancer, said: “It’s disappointing that this research programme did not show a reduction in mortality from ovarian cancer and so can’t be recommended as a national screening programme. However, the impact it had on earlier diagnosis is impressive and important.
“Earlier diagnosis will often reduce the amount and intensity of treatment, and this makes all the difference to women and their families who are living with cancer. It may have also given them more precious time with their loved ones.”
Other screening methods are also being developed, but it could take years to know if these would save more lives. For now, the focus should be on improving awareness of the most common symptoms and ensuring that women who experience them are promptly referred to an oncologist, said Usha Menon, a professor of gynaecological cancer at UCL, who led the study.
“Symptoms of ovarian cancer can be quite vague and similar to symptoms caused by less serious conditions, which can make spotting the disease tricky,” said Michelle Mitchell, Cancer Research UK’s chief executive. “Whether it’s needing to go to the toilet more often, pain, bloating, or something else, raise it with your GP – in most cases it won’t be cancer but it’s best to get it checked out.”
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