An innovative blood test that can detect the presence of over 70 different types of cancer cells is now available in Malta.

Called Trucheck, the blood test was created by UK-based molecular oncology facility Datar Cancer Genetics and is being offered at Saint James Hospital’s Medical Laboratory Services at the cost of €1,200.

However, while it is regarded as a potentially important tool for early cancer detection, questions remain over the clinical benefit of the test to the patient.

We still need to gain the experience and increased knowledge to know where they will fit in our management of this common and dreaded disease- Stephen Brincat, director of Oncology Services at Saint James Hospital

The test, which underwent extensive clinical validations involving more than 40,000 participants, has a sensitivity of around 88 per cent and is around 96 per cent accurate, according to Stephen Brincat, director of Oncology Services at Saint James Hospital.

Test not a replacement for routine cancer screening

The non-invasive blood test detects the presence of circulating cancer cells in the blood and can pinpoint the location or tissue of origin for certain types of cancers that include melanoma and cancer in the breasts, lungs, thyroid, liver and more.

However, the catch is that a negative result means there are no cancer cells in the blood at that particular point in time. This means the test has to be carried out regularly and is not a replacement for routine cancer screening.

A positive result, on the other hand, means that while there are cancer cells in the blood, a patient would not necessarily need treatment. The cancer cell detected might die off alone or might be a sign of a tumour that will form decades later.

“These tests exist and are locally available but we still need to gain the experience and increased knowledge to know where they will fit in our management of this common and dreaded disease,” said Brincat.

“The very high level of detection may, in fact, be a problem. The fact that most cancer cells in the circulation are destined to die and, therefore, not cause any problems raises the issue of whether a positive test that identifies cancer necessitates treatment… It would necessitate further investigation to locate the primary cancer.

“In about three per cent of cases who are asymptomatic, and negative for all other screening tests, no cancer will be found. This creates a quandary.

“Not finding a cancer does not mean it does not exist but equally finding cancer cells in the blood does not automatically mean that that person will need treatment,” he said.

'Cancer has a head start of millions of years'

Brincat adds that for any one of the commoner cancers to reach a readily detectable size of 1cm, it would have been growing for 10 years or more. During this time, it would be shedding cells into the circulation and paradoxically it is more likely to do so early in its life history rather than late.

“What this means is that we can have a positive test many years before we can detect a cancer by other means, even if the test tells us where the primary is likely to be. This is not necessarily a good thing.

“What we can say for sure is that when it comes to outcomes, we have made more progress in prevention and early diagnosis than we have in treatment and the increasing understanding of the biology of cancer tells us why this is so. Cancer has an evolutionary head start on us of several hundred millions of years but we are catching up,” he said.

How it works

Trucheck detects circulating tumour cells and clusters of these cells which are released by malignant tumours.

Brincat explains how a cancer can spread through the body in a number of ways. The most dangerous mode of spread is through the vascular system including the lymphatic system.

“Here cancer cells find a network of roads and means of transportation that can carry them throughout the body. The very large majority of cancer cells that get into the circulation are destroyed. They either self-destruct through a process called apoptosis or they are destroyed by the immune system,” he explained.

But some make it through and, once inside the circulatory system, can give rise to a secondary tumour, the dreaded metastasis.

Through this test, the cells in the blood sample taken are treated with an agent that would normally cause apoptosis even in normal cells. The apoptotic resistant cancer cells survive and can be selected out to make a diagnosis.