London, Thanasis Gavos

One blood test which detects traces cancer cells could prevent her chemotherapy for thousands cancer patientsaccording to researchers at London’s leading cancer hospital, the Royal Marsden.

What they are looking at is whether the test can be widely and reliably used to confirm whether surgery in bowel cancer patients has removed all the tumour.

The research is being done because half of patients with stage three bowel cancer are treated with surgery alone, as the tumor is completely removed. Therefore in these cases the intravenous chemotherapy to which the patients are subsequently subjected is actually unnecessary.

About 1,600 patients with bowel cancer are participating in the research. The test they are given has the ability to detect microscopic traces of cancer in the blood, which are not visible on CT and MRI scans.

The absence of such traces in the blood implies, according to the researchers, that the patient has been cured by the operation.

Dr Noreen Starling, head of the researchers, speaking to the BBC, said avoiding unnecessary chemotherapy “is good for the patient, good for the health system, good for saving the NHS”.

The blood test has been developed by the American company Guardant Health. Samples are sent for analysis to the company’s laboratories in California and results are returned within a fortnight.

The purpose of the research is more broadly to determine whether the survival rates of bowel cancer patients whose treatment is determined using the specific blood test improve, compared to those who are subject to the usual process of referral to chemotherapy.

Similar clinical trials are being conducted in the UK for patients with lung cancer, breast cancer and dozens of other difficult-to-diagnose types of cancer. In total, more than 140,000 volunteers participate in the tests.

Dr. Starling added that this particular method of using so-called “wet biopsy” blood tests holds enormous potential, not only for checking the degree of removal of cancerous tumors after operations, but also for faster diagnosis.

The presence of traces of cancerous tumors in the blood can be detected more quickly in comparison with traditional methods of diagnosis.

A study by Greek scientists from the Department of Chemistry of the University of Athens that was published in January in the journal Nature showed that liquid biopsies can detect the presence of breast cancer even four years before a mammogram.