Why isn't screening available for all cancers?
Currently the UK has 3 national screening programmes - bowel, breast and cervical. Screening programmes can only be set up for a particular cancer type if it will save lives without too much risk. For the current UK programmes there is evidence that this is the case.
A screening programme needs to have a good enough test for it to work. This test must:
- reliably detect any cancers or abnormal changes that could lead to cancer
- not cause too many false alarms
- be acceptable, so that people will actually take the test
- not be dangerous to health
- be cost-effective.
If a test doesn’t do these things, it’s unlikely to be effective for screening the whole population.
If a cancer is rare, it wouldn’t be an effective use of time and money to screen the entire population, and it would be harder for the benefits to outweigh the harms. It would also cause unnecessary worry for those being screened. If good tests are available for rarer cancers, doctors will often offer them to people who have the highest risk of the disease.
If there isn’t a good enough test, or if there isn’t enough evidence that screening would save lives and not cause too much harm, then screening isn’t introduced.
At the moment, there isn’t enough evidence to say that screening for any type of cancer other than breast, bowel, and cervical cancer would be a good idea.
But researchers are always looking for new tests and new ways to spot cancers early, and there are some types of cancer where the evidence about screening is growing, for example, lung and ovarian cancers.
There is no screening programme for prostate cancer because we don’t have a reliable enough test to use, and the test available at the moment has significant risks.
A test called the PSA test can help doctors to work out how likely a man is to have prostate cancer. But this test is not reliable enough to use as part of a national screening programme.
It misses lots of men who do have prostate cancer, and it leads to lots of unnecessary diagnosis and treatment, which can have serious side effects. And while some trials have shown it could save lives from prostate cancer, others have shown it has no benefit. Overall, the evidence shows that screening for prostate cancer doesn’t reduce the number of men dying from the disease, but does increase the risk of harms such as overdiagnosis, where slow-growing tumours that wouldn’t cause a man any harm are picked up.
If you’re a man over 50 and want to have a PSA test you can ask your doctor. They will give you information about all the pros and cons of having a PSA test to help you make a decision.
At the moment there is no screening programme for lung cancer in the UK.
There have been some trials looking at using a type of CT scan to screen for lung cancer in older smokers or ex-smokers. There is some evidence that this type of screening could save lives from lung cancer. But it also looks like it will lead to unnecessary diagnosis and treatment, so the balance of benefits and risks isn’t fully clear yet.
There is another big trial going on in Europe at the moment, which should provide more information. Then, the National Screening Committee will look at the evidence and decide whether screening should be introduced in the UK.
At the moment, there is no screening programme for ovarian cancer in the UK.
There is a trial going on in the UK at the moment looking at a combined ultrasound and blood test to detect ovarian cancer, but the results have not been released yet. When this type of screening was tested in the USA, they found it didn’t save lives.
Once the results of the UK trial are available, the National Screening Committee will look at the evidence to decide whether screening should be offered.