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Understanding the different cancer tests available, including a new multi-cancer early detection test, can help you make an informed choice about the way forward.

THE MESSAGE IS CLEAR: CERTAIN CANCERS ARE PREVENTABLE, AND MANY CANCERS ARE TREATABLE AND CURABLE, ESPECIALLY WITH EFFECTIVE TREATMENT IN THE EARLY STAGES. That is often the case for common types like breast and colorectal cancer, which have well-established screening tests. But about 70 per cent of all cancer deaths come from those diseases for which there are currently no proven screening tests¹. Such cancers are often diagnosed at an advanced stage, making them harder to treat.

Fortunately, scientific advances are reducing the mortality rate, with new tests like multi-cancer early detection (MCED) paving the way for earlier detection of different cancers. This article explores this new approach and examines other methods that have been a mainstay of cancer diagnosis.

RECOMMENDED SCREENINGS

The general public is strongly encouraged to adhere to recommended screenings throughout their lifetime, including mammograms for breast cancer, Human Papillomavirus (HPV) tests for cervical cancer, and colonoscopies for colorectal cancer. These tests detect tumours that have the potential to become cancerous in the future. Such cancers are less likely to spread, so removing tumours before or even after they turn malignant can be effective in tackling the disease.

GENE TESTING

Dr Colin Phipps Diong, Senior Consultant, Haematology, Parkway Care Centre, often encounters patients interested in genetic testing to assess their risk of blood cancers, including leukaemia. Tests like the Clonal Haematopoiesis of Indeterminate Potential (CHIP) review can identify genetic mutations associated with blood cancer.

At present, CHIP is not recommended as a screening tool for blood cancers. However, Dr See Hui Ti, Senior Consultant, Medical Oncology, Parkway Cancer Centre, likens the CHIP test to a “snapshot in time” that can help patients with elevated risk. “It is useful as it indicates that you may have an alarmingly high inflammation at that moment,” she explains. “You can then have a realistic conversation with your doctor about your next steps.”

Dr Diong stresses the importance of weighing the pros and cons before undergoing regular gene testing. “Finding a mutation often raises more questions than answers,” he points out. “What is the chance of developing leukaemia after a mutation is detected? It is very low, and there are no preventive medications currently available to stop the mutation becoming cancerous. But the psychological impact can be significant, and health insurance may be affected. These are considerations patients should discuss with their doctor.”

TUMOUR MARKER TESTS AND PET-CT SCANS

Tumour marker tests are another type of testing that is commonly misunderstood. A tumour marker is a substance, often a protein, that is produced in the body in response to cancer growth or by the tumour itself. Their presence can be detected in the blood, urine or tissue samples. While tumour marker tests are promoted as a means of early cancer detection, Dr See notes they are most effective in monitoring cancer recurrence among patients who have previously had the disease. For patients who have never had cancer, the test may lead to false positives. This is because tumour markers are also produced by some normal cells in the body and levels may sometimes be significantly elevated in non-cancerous conditions.

A false positive occurs when the test indicates the presence of cancer when it is not actually there. The anxiety associated with false positive cancer screenings can be emotionally taxing. Conversely, a false negative arises when the test incorrectly shows an all-clear result. This can give patients a false sense of security, which can lead to delays in treatment and potentially worsen outcomes.

For PET-CT scans, which provide detailed information about the structure and function of cells and tissues in the body, Dr See advises a cautious approach due to their cost and radiation risks. “Perform the test only when your doctor prescribes it,” she says.

MULTIPLE CANCERS, ONE TEST

MCED blood tests have garnered widespread attention for their potential to detect different types of cancer from a single blood sample. They work by identifying biological signals (or biomarkers) shed by cancer cells. Cancers that can be identified through these tests include lung, nasopharyngeal, prostate and pancreatic cancers. “In the case of a positive MCED blood test, the test may localise the cancer signal to the affected organ. If this cannot be determined, further investigations like full-body scans may be needed,” explains Dr Tan Min-Han, Founder and Medical Director of Lucence, a biotechnology company that develops these tests.

Dr Tan recommends using MCED blood tests for individuals with elevated risk. As with other medical tests, MCED blood tests carry a risk of false positives and false negatives.

Thinking of skipping screening? Think again

Do not let misconceptions about cancer screening get in the way of getting yourself checked.

“I feel okay. Screening once is sufficient.”

Feeling fine does not guarantee you are cancer-free. Many early-stage cancers often present with no symptoms, and when they manifest, the disease might be advanced. Regular screening, according to recommended guidelines, is crucial in detecting treatable early-stage cancers. Delaying until symptoms arise complicates diagnosis and treatment. Furthermore, most screenings are brief and tolerable, often under 30 minutes.

“Exercising regularly and eating healthily is good enough.”

While a healthy lifestyle is essential for overall health, it does not negate the need for regular screenings. Even those with healthy habits can develop cancer. Screening complements a healthy lifestyle.

“I am not at risk as I do not have a family history of cancer.”

While genetics can influence cancer risk, many cancers arise from environmental and lifestyle factors like smoking, diet and carcinogen exposure. Everyone, irrespective of family history, can be at risk. Regular screenings are crucial for early detection, capturing cancers from all causes.

MCED blood tests have garnered widespread attention for their potential to detect different types of cancer from a single blood sample. They work by identifying biological signals (or biomarkers) shed by cancer cells.

¹ https://www.cancer.org/cancer/screening/multi-cancer-early-detection-tests.html