{"id":27984,"date":"2022-04-14T07:00:01","date_gmt":"2022-04-14T07:00:01","guid":{"rendered":"https:\/\/news.cancerresearchuk.org\/?p=24193"},"modified":"2024-11-03T15:13:41","modified_gmt":"2024-11-03T15:13:41","slug":"detecting-multiple-cancers-with-a-simple-blood-test-where-are-we","status":"publish","type":"post","link":"https:\/\/ogkologos.com\/en\/detecting-multiple-cancers-with-a-simple-blood-test-where-are-we\/","title":{"rendered":"Detecting multiple cancers with a \u2018simple\u2019 blood test: Where are we?"},"content":{"rendered":"
\"Close-up<\/div>\n

\u201cIt\u2019s always been a dream for many clinicians and scientists to be able to detect cancers with a simple blood test,\u201d says Dr Amit Roshan, a clinician scientist at the University of Cambridge who works on the early detection of melanoma skin cancer.<\/p>\n

A blood test capable of catching any cancer at an early stage before any symptoms may sound like science fiction, but Amit says that not everyone has that impression.<\/p>\n

\u201cMany patients, even today, when they come to my clinic, find it very unusual that they can\u2019t have a blood test to detect their particular type of cancer.\u201d<\/p>\n

Whilst Amit notes that while there can be a mismatch between people\u2019s hopes and expectations and the reality of what\u2019s available, significant progress has still been made in this area.<\/p>\n

In September 2021, a new blood test<\/a> that has the potential to detect over 50 kinds of cancer began trials in the NHS, sparking renewed excitement in the \u2018holy grail\u2019 of improving our ability to catch cancer early, when it\u2019s far more treatable.<\/p>\n

And while this test \u2013 the Galleri test \u2013 is the first of its kind to be trialled on this scale in the UK, it\u2019s not the only player on the field.<\/p>\n

So how close are we to these tests becoming a routine part of medicine? And are they the silver bullet some might hope them to be?<\/p>\n

How could these tests actually work?<\/h2>\n

When searching for signs of cancer in the blood, there are many avenues to explore, but there are 3 main clues that researchers are following: metabolites, proteins, and DNA.<\/p>\n

Cancer cells can grow in many different ways when compared to healthy cells. This often leaves a distinct imprint of metabolites. These are substances that are made or used when the body breaks down nutrients, drugs, chemicals or its own tissue. Identifying and analysing these metabolites can help to fingerprint cancer or the body\u2019s response to treatments.<\/p>\n

Measuring proteins<\/h3>\n

Analysing the levels of proteins in the blood is a well-known method for identifying the presence of some cancers. This is because some proteins are either produced by the cancer itself or by the body in response to the cancer (and may not be present in the same levels in healthy individuals).<\/p>\n

CA125 is a protein often found on the surface of ovarian cancer cells and in some normal tissues. High levels can be a result of conditions like endometriosis, fibroids and even pregnancy but also ovarian cancer<\/a>.<\/p>\n

Searching for DNA<\/h3>\n

In healthy individuals, cells in the body can release fragments of DNA into the blood when they die and these fragments are known as cell-free DNA.<\/p>\n

These fragments allow us to get an insight into the body, as levels of fragments released by different cells can be used as a marker for different conditions \u2013 including cancer.<\/p>\n

In people with cancer, some of the cell-free DNA found in the blood comes from the death of tumour cells and is known as circulating tumour DNA (or ctDNA). Being able to identify and measure the presence of these fragments could be a non-invasive way to diagnose cancer at an early stage.<\/p>\n

Tests designed to pick up one or more of these clues are the furthest along at the minute, but they\u2019re not the only approaches being investigated. The best method may still be yet to come, and may involve a combination of clues rather than a single one.<\/p>\n

And while a lot of focus has been on \u2018simple\u2019 blood tests, they\u2019re not the only place scientists are searching. Our researchers are also looking at the potential for breath tests to pick up multiple cancers<\/a>, for example. But that\u2019s a story for another time.<\/p>\n

What are the challenges with blood?<\/h2>\n

\u201cWe\u2019ve already developed highly sensitive tests to detect cancers in the blood. But they\u2019ve all been for single cancers<\/a>,\u201d says Amit.<\/p>\n

There\u2019s already a challenge in finding ctDNA for one cancer type \u2013 it\u2019s a needle in a haystack.<\/p>\n

One of the main challenges to overcome is that ctDNA analysis must detect the minute fragments of DNA released by tumour cells. These fragments are only one small fraction of all of the cell-free DNA in the blood. This means that the ctDNA \u2018signal\u2019 that is being searched for can be drowned out by lots of noise \u2013 diluted by many other molecules in the blood.<\/p>\n

This becomes even more complex when you\u2019re trying to detect multiple types of cancer with a single blood test.<\/p>\n

Different tumours release different types of ctDNA and this makes it particularly difficult to detect fragments, especially at early stages of tumour development. So instead of searching for a needle in a haystack, it\u2019s more like searching for multiple tiny needles in a haystack and then<\/em> having to sort them.<\/p>\n

However, researchers have developed tools, such as looking at groups of common mutations or methylation patterns (chemical changes to DNA) to help us differentiate ctDNA from DNA from normal cells. This means that you don\u2019t need to know exactly what type of cancer that you\u2019re looking for.<\/p>\n

But it\u2019s not enough to know that somebody has cancer, we also need to know where that cancer is most likely going to be,\u201d says Amit. Having this information should direct follow-up tests and help speed up diagnosis.<\/p>\n

When could we see these tests in practice?<\/h2>\n

Amit notes that some of these tests have already moved beyond lab testing and are now in large trials to see how effective they are.<\/p>\n

Although several more are in progress, there are 3 tests which have reached advanced stages of development:<\/p>\n