Danish researchers and international collaborators have developed a method for detecting all types of cancer in the early stages through a blood test. This method may eventually save many people’s lives.
Imagine that doctors could use a simple blood test to tell you not only whether you have cancer or not but also, if you do have cancer, where it is located.
This may sound like wishful thinking, but this dream is actually not as fanciful as it may seem.
Danish researchers have developed a method that enables researchers and doctors to diagnose all types of cancer very accurately by using a blood test.
“If we can achieve this, it will be quite revolutionary and will mean that we can detect cancer before the disease progresses to a stage at which treatment becomes difficult. We can also identify where the cancer is located. Both identifying that a person has cancer and its location are vital in hospital investigations,” says a Danish contributor to the study, Claus Lindbjerg Andersen, Professor, Department of Clinical Medicine, Aarhus University and Department of Molecular Medicine, Aarhus University Hospital.
The Danish researchers and colleagues from the Netherlands and the United States recently published their results in Nature.
Cancer cells leave unique DNA fragments in the blood
The method is based on the fact that different types of cancer leave different DNA signatures in the blood.
The blood vessels in cancerous tissue often leak, which means that DNA from fragmented cancer cells can enter the bloodstream and thus circulate in locations where it should not normally be.
This means that the blood suddenly contains fragments of DNA from, for example, lung cancer cells, liver cancer cells or prostate cancer cells.
Further, DNA is folded differently in different types of cancer cells, depending on where the cancer is located. The researchers can measure these differences through a blood test to detect not only whether people have cancer but, if they do, what type of cancer it is.
“Our study is a proof-of-principle study in which we have demonstrated that a blood test can detect cancer,” says Claus Lindbjerg Andersen.
Identifies cancer in 73% of cases
The researchers used their method to analyse the DNA fragmentation profiles of 236 people with breast, colorectal, lung, ovarian, pancreatic, gastric or bile duct cancer. The blood test detected cancer in 73% of the cases.
In addition, the method differed in how effectively it could identify the different types of cancer.
For example, the blood test detected only 57% of breast cancer cases but more than 99% of lung cancer cases.
“The current sensitivity of our method means that some individuals will have insufficient cancer cell DNA in their blood so that we cannot detect it in the amount of blood we examine,” explains Claus Lindbjerg Andersen.
However, Claus Lindbjerg Andersen also says that the researchers are constantly trying to refine the method to detect cancer more accurately.
Eliminating false-positive results
The researchers also tested the method on 245 healthy individuals and identified four as having cancer, even though they did not: false-positive results.
Eliminating false-positive results is important for the future of this method because there should be very few if the healthcare system is to screen people for cancer though blood tests on a large scale. This especially applies to screening older people for cancer, since they often have high blood pressure, diabetes and other conditions that may, but hopefully will not, affect the outcome of the blood tests.
The researchers are therefore testing their method on both older people and people with various lifestyle-related diseases to ensure that ageing and diseases other than cancer do not affect the results of the blood tests.
“We do not expect that ageing and other diseases than cancer will affect our test results, but we have to exclude this possibility before we can proceed with developing our method. We need to know that being older and having other diseases do not do anything to the body that may be mistakenly identified as cancer in our test,” explains Claus Lindbjerg Andersen.
Monitoring people with cancer after treatment
In addition to minimizing the risk of false-positive results, the researchers are also conducting experiments that test various applications for their cancer screening.
In particular, Claus Lindbjerg Andersen suggests that the blood test may be useful after cancer treatment.
After someone has been treated for cancer, doctors currently do not have many good methods to determine whether the cancer has disappeared completely or whether some has survived and is just waiting to grow again.
The major problem is that the survival rate for individuals whose cancer has returned is less than 10% over 5 years. A common reason is that the cancer is not detected early enough to treat it effectively.
Thus, one can imagine using the new blood test to continually monitor whether people’s cancer returns. The researchers are conducting a new clinical trial to examine the effectiveness of this strategy.
“The goal is to use blood tests to monitor people with cancer so that we intervene with treatment as soon as we see signs of the disease returning. This will save many lives, because today we are not very good at finding the residual disease early enough for us to start effective treatment,” says Claus Lindbjerg Andersen.
“Genome-wide cell-free DNA fragmentation in patients with cancer” has been published in Nature. In 2017, the Novo Nordisk Foundation awarded a grant to a co-author, Claus Lindbjerg Andersen, for the project Implementing Non-invasive Circulating Tumour DNA Analysis to Optimize the Operative and Postoperative Treatment of Patients with Colorectal Cancer.
