Are cancer screening tests effective?

Thanks to Rebecca Fitzgerald for the answer!

James - Cancer Research UK estimates that roughly one in two of us will develop some form of cancer in our lifetime. Survival rates are improving as we continue to develop better treatments, which are most effective when we catch cancers in their early stages. That's where screening tests come in. The more we deploy and the more effective they are, the more we can improve outcomes for cancer patients. But when it comes to screening tests, there are different kinds, each with their own strengths and weaknesses. As a rule of thumb, a general screening test might be less likely to pick up a cancer than a test specifically designed to catch that kind of malignancy. But does that mean they aren't worth taking? Here's Rebecca Fitzgerald, professor of Cancer Prevention and Director of the Early Cancer Institute at the University of Cambridge.

Rebecca - Yes, I think that the development of blood tests that can screen for multiple cancers is a really exciting new field. The technology's advancing very rapidly, and so it's still relatively early days to be sure how accurate these tests will be, particularly for early stage disease. The detection rate is generally low for early stage cancers, though there is some complexity. For example, there's some evidence that they may detect more aggressive cancers earlier than less aggressive ones. That's a very good thing, but it's also important to be aware that some cancers may be easier to detect than others through DNA and proteins shed into the blood.

James - Interesting. So could these tests carve out a role for themselves amongst our current screening initiatives?

Rebecca - Overall, I think we need more evidence from trials to understand which of these tests work best. There are lots of companies developing the tests and they're really focused on how they might be used clinically. For example, should we use them to test individuals with no symptoms? And if so, at what age? How often should we test to maximise their clinical usefulness and avoid false negatives? How do they complement existing screening tests and what happens if the test is positive and no cancer is found? What do we do then?

James - These are the questions health services will have to weigh up when deciding whether to add them to their toolkit, given that they can be pricey. But what about for an individual who might have the cash? Would you recommend taking a test like this?

Rebecca - My advice would be to take part in trials as that's how we answer these questions and advance the field. However, based on the current evidence, I wouldn't recommend paying for a multi cancer blood test for screening outside of a trial.