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A Doctor explains why a clinical trial involving many thousands of women is needed.
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What's happening at present is that there is a very big randomised controlled trial in the UK, that is a trial in which half of the women involved are being screened and the other half of the women are not being screened. The study will take 10 years to complete. It will be complete in around about 2010 - 2011. It's already 2-3 years' progress has been made. At the end of that study all of the information needed will be available for the Department of Health and the government to make a decision about whether or not to introduce ovarian cancer screening alongside cervical and breast cancer screening. And the sort of information that's needed is: does ovarian cancer screening save lives? If it does save lives, how much does it cost to do that? And what is the down side of screening: how much anxiety does screening cause, how many false positives are there, how many unnecessary operations result from the false positives, and how many women have serious complications as a result of that unnecessary surgery? So there's quite a fine balance to be reached here in, with the issue of screening. That big study is called the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).
The UKCTOCS trial is designed so that recruitment is over 3 years and it's recruitment of 200,000 women, and 160,000 of them are recruited as of now in mid-2004. During the next year the remaining 40,000 will be recruited, so by 2005 all of the women will be participating in the study. The screening will then continue till 2010, and by 2011 or 12 we will have the mortality data, so we'll be able to see for the first time whether ovarian cancer screening really does save lives. |
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A Doctor explains that symptoms usually occur when ovarian cancer is already advanced and that the symptoms may be caused by other things.
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One of the major problems with ovarian cancer is that there are very few symptoms of the cancer when it's in its early stages. The symptoms really reflect the fact that the cancer has spread outside the ovaries to the surfaces within the abdominal cavity and the pelvis, and are symptoms of advanced stage cancer. So the symptoms by and large are of abdominal swelling, and vague discomfort, of indigestion, sometimes of frequency passing urine, but they're not specific to ovarian cancer, they're common in all sorts of other conditions. Most of the women who develop ovarian cancer are over 50 years of age and have reached the menopause, and many of those women will have symptoms of abdominal swelling or distention or indigestion for all sorts of other reasons which have nothing at all to do with ovarian cancer. In fact the vast majority of women with the symptoms that occur in advanced stage ovarian cancer will have entirely benign conditions.
So is there nothing that's specific to ovarian cancer or even to a gynaecological condition?
There's a lot of work going on to see if its possible to identify what we might call a symptom complex which would be helpful in picking up ovarian cancer earlier than it's currently detected. There are all sorts of problems with that. Not least, the first problem, that if we pick out women on the basis of those symptoms, the vast majority almost certainly will not have ovarian cancer, although we may include rather more women with ovarian cancer than would otherwise be in a population picked for screening. The other problem is that even if we can identify symptoms that allow us to identify ovarian cancer earlier in some women, we still don't really have any evidence that we'll be picking up ovarian cancer early enough to save the lives of those women, so we may be picking it up a little bit earlier in the course of the disease, but perhaps not early enough to make a real difference. |
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A Doctor explains that it's difficult for GPs to recognise which women with symptoms have ovarian cancer and that diagnostic delays are inevitable.
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A large number of women who have ovarian cancer will have been to their GP several times over the previous months complaining of vague symptoms which could be irritable bowel syndrome, could be constipation, could be related to weight gain, could be related to all sorts of different things. Is there any way in which we can separate out those very small number of women from the much larger number of women with those other conditions? There is no way that has yet been devised. It is still extremely difficult for GPs to diagnose ovarian cancer, and the more we increase the GPs' awareness of ovarian cancer the more we run the risk of causing a great deal of anxiety amongst the large number of women who don't have the disease, and of making them have unnecessary investigations. It's very hard to decide where the balance lies.
I think the GPs are in a very, very difficult situation with ovarian cancer because it is a relatively uncommon cancer. The average General Practitioner will see just one, two or three women who have ovarian cancer during their entire career. So to expect them to be able to pick out ovarian cancer from the probably hundreds of other conditions which might cause similar symptoms is asking a great deal in general practice.
I think we should do all we can to make GPs more aware of ovarian cancer as a cause of symptoms but we will probably never get away from the situation in which there are some delays in diagnosis. It really reflects the disease rather than any shortcomings of general practitioners. |
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A Doctor describes the various tests used to diagnose and assess the spread of ovarian cancer.
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If a woman has symptoms suggestive of ovarian cancer, the first thing, of course, would be for her doctor to examine her, and the examination would include an examination of the abdomen, as well as an internal examination to see if there's a mass, a lump, which can be felt in the pelvis. If after the examination there is a real suspicion of the possibility of ovarian cancer the next two straightforward tests would be an ultrasound scan, the same type of scan as performed in pregnancy, which can give a good picture of the size, shape and texture of the ovaries, and a blood test called CA125 which is raised in the majority of women, not all women, but in the majority of women who have ovarian cancer.
Those tests can either be, sometimes they'd be requested by the general practitioner, in other situations the GP would refer the patient into hospital and may be requested through the hospital. If the ultrasound scan and the CA125 suggest that there is an ovarian cancer present, sometimes no further investigations will be required, and in some instances it will be possible to go on to treatment just on the basis of the examination, the CA125 and the ultrasound. That treatment would normally be surgery in the first instance. In other situations, the CA125 and ultrasound may be uncertain or unclear, or more information may be needed before proceeding to treatment.
And then more sophisticated investigations may be performed, like a body scan, a CT scan, or an MR scan. They can give more information, not only about the condition of the ovaries, but also about the rest of the abdomen and pelvis, and give information about whether or not the cancer has spread outside the ovary. |
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A Doctor describes the aims of research into screening for ovarian cancer.
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Because ovarian cancer doesn't cause symptoms until it's reached an advanced stage, a lot of hope has been attached to the possibility of screening for early detection of ovarian cancer, and work on this goes back 20-30 years. The rationale is that if a test can be used which will pick up the cancer when it's confined to the ovary it may be possible to transform the outcome and to successfully treat the patient just by removing the ovaries and the womb without the need for chemotherapy or any other form of treatment. And the survival rates for stage 1 ovarian cancer, that is ovarian cancer which is genuinely confined to one or both ovaries, are over 90% at 5 years after treatment, whereas the overall survival rates for ovarian cancer at present are 30-40%. So if we could pick up the vast majority of women with ovarian cancer with stage 1 disease, it's possible, but not absolutely guaranteed, it's possible that we would transform the outcome for many, many thousands of women. |
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A Doctor describes why screening has not yet been introduced despite some evidence that it can detect ovarian cancer earlier.
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Some people will say when they hear that, 'Fantastic. Why don't we screen for ovarian cancer in everyone?' And there are several reasons that we're not introducing this yet as a national screening programme. One is that, although the tests can pick up ovarian cancer, they don't pick it up in everyone. So they will pick up something in the range of 80 - 90% of women who have ovarian cancer; they're not foolproof. The second and more important reason is that the tests are quite often abnormal even in women who do not have ovarian cancer. So there are false positive results associated with these tests.
Ovarian cancer is a relatively uncommon cancer, so that if we're not careful, for every woman picked up with these tests who has cancer, we will end up operating on many, many other women who don't have cancer, and some of those women will have complications, and in fact in some of the studies a small number of women who had false positive screening tests with CA125 or ultrasound have died from complications of surgery even though they did not have ovarian cancer. So we have to be very, very careful about that.
And the final reason for not offering screening immediately to everyone is that we haven't yet proved that picking the cancer up with the screening test earlier actually saves lives. Now some people say 'If you pick it up earlier surely it saves lives?' Well the answer is not necessarily. We could be picking it up early, but we may not be picking it up early enough to prevent the cancer spreading and to make the disease curable by the treatment that's available. So it's too early to offer this sort of screening to every woman in the population. |
