In order to increase the probability of successful cancer treatment, it is important to detect the cancer as early as possible. According to the World Health Organization (WHO) and other sources, two different methods can be distinguished for cancer detection.
Early diagnosis and cancer screening
First is early diagnosis, where symptoms are already present and the cancer is identified as a cause of these symptoms. The second method is screening, where different tests are performed on individuals where symptoms have not manifested yet, but the cancer could already be present. These tests include mammogram, breast magnetic resonance imaging (MRI), prostate-specific antigen (PSA) test, digital rectal exam (DRE), smear tests, colonoscopy, etc. However, there are several disadvantages with these tests (e.g. injuries, anxiety, incorrect results, possibly harmful additional tests, …), which have led to different requirements and/or recommendations to perform them. For example, specific screening programmes are recommended for people above a specific age (e.g. in Europe are mammography screening programmes for women aged 45 to 74 years).
How do multi-cancer early detection (MCED) tests work?
Lately, a lot of attention caught multi-cancer early detection (MCED) tests, since they are also being advertised to a broader audience. The main premise of MCED tests are markers that can be found in a body fluid (blood, saliva and urine), when cancer is present in the body. Usually, a blood sample is taken and checked for signs of cancer (fragments of DNA, RNA, proteins, etc.) with the help of machine learning algorithms. Although these tests are not a cancer diagnosis, additional tests can lead to cancer identification (type, stage and location). In a way they act as a precursor for cancer identification.
Current research and accuracy of MCED tests
Nic Fleming in the Nature article Are multi-cancer blood tests ready for prime time? checked the current research and findings on the MCED tests. Currently, there are around 40 different MCED tests on the market or in development. Some of these tests could detect even more than 50 different types of cancer, while others considerably less (2 or more). However, since early-stage cancers are connected with a considerably low amount of markers in the blood, these tests have to be very accurate to be efficient in cancer detection. To achieve adequate accuracy, researchers are developing different methods and approaches to address this challenge (analysis of circulating tumour DNA, genetic mutations, methylation patterns, etc.).
Some MCED tests have already undergone studies and assessments regarding their use on a broader scale. While the percentage of identified people without cancer is relatively high (96-99%), the percentage of identified people with cancer is still quite low in some cases (27-38% or less), but higher in other cases (61-80%). These results suggest that the MCED tests can lead to cancer detection, but there is still a lot of research and improvements needed to provide more accurate results, along with the assessment in the scope of the randomised controlled trials (RCT). Their use might be generally appropriate in cases where other options are not available, since screening tests can be performed only for specific cancer types. Despite that, MCED tests should not be considered as a replacement for screening tests. Questions also arise regarding the target population and optimal age range for MCED tests.
Are MCED tests approved by health authorities?
As a result, they haven’t been approved by health authorities like the Food and Drug Administration (FDA) in the United States of America yet, although some of them can be used under specific conditions (American Cancer Society on Multi-cancer Detection Tests). Therefore, at this stage, the MCED tests can still be considered as evolving technology, but they have promising features in cancer detection.
MCED tests and the IFIGENEIA project
While the European project IFIGENEIA is not directly connected with the MCED tests, one of our goals is to provide useful information and insights in the relevant topics in the field of cancer.
Recommended reading:
- Are multi-cancer blood tests ready for prime time? (Nature)
- Screening: Learn More – Advantages and disadvantages of screening tests (National Library of Medicine)
- Multicancer early detection testing: Guidance for primary care discussions with patients (National Library of Medicine)
- Guide to cancer early diagnosis (WHO)
- A short guide to cancer screening – Increase effectiveness, maximise benefits and minimise harm (WHO)