‘Liquid biopsy’ study offers hope for a blood test to find cancer

CHICAGO: The biggest study to date on new blood tests to detect and analyse cancerous tumours concluded that such “liquid biopsies” are a reliable alternative to conventional biopsies, offering a potentially cheaper and less invasive way of monitoring malignancies.

The study, which involved genetic information from more than 15,000 patients and 50 tumour types, compared tumour samples from liquid biopsies with those from traditional biopsies. In the vast majority of cases, the genetic changes detected by the blood tests agreed with the mutations identified in the tissue biopsies.

“The findings suggest that liquid biopsies provide an accurate snapshot of the genomic landscape of the tumour,” said a news release that accompanied the data, which was released on Saturday at the annual meeting of the American Society of Clinical Oncology here.

Liquid biopsies are a hot field, with several companies, including Foundation Health and Grail, either marketing tests or working to develop them. Such tests are designed to pick up in the bloodstream small pieces of DNA shed by cancerous tumours - information that then can be used to treat and monitor the disease.

Currently, doctors largely use surgical biopsies for information about a tumour’s genetic mutations and whether the cancer can be treated with available drugs. But such biopsies are invasive and can be expensive and painful. In addition, patients aren’t always healthy enough to undergo them, and sometimes not enough tissue is procured to allow pathologists to conduct high-level analysis.

Philip Mack, director of molecular pharmacology at the University of California at Davis’s Comprehensive Cancer Centre, who presented the findings, said the study indicates that a liquid biopsy can be a “highly informative, minimally invasive

The findings suggest that liquid biopsies provide an accurate snapshot of the genomic landscape of the tumour. News release

alternative” to a traditional biopsy, especially when the cancer is in a difficult-to-reach location such as the brain.

He also said at a news briefing that two-thirds of the liquidbiopsy results in the study were “actionable,” meaning patients had mutations that could be treated by drugs.

In the study, the liquid biopsyresults were compared with conventional biopsies in two ways. For 398 patients, DNA circulating in the bloodstream was compared with tissue samples previously removed from patients. For the rest of the patients, researchers compared blood-test results to those for tissue biopsies in data from large databases.

Mack and other physicians said that traditional biopsies will remain the “gold standard” because they provide more information on the characteristics of tumours and how they might likely develop. Mack said a trained pathologist can determine what kind of tumour is present based on the appearance of cells in a tissue sample - and whether cancer a extracted from the liver actually originated somewhere else, like in the lung.

But he added that one of the benefits of the liquid biopsy is that it can be done at lower cost and with less effort repeatedly to monitor changes in a tumour over time.

One area in which the two types of biopsies didn’t agree as much involved mutations indicating resistance to therapies.

Those were picked up in the blood tests but not in the tissue samples - perhaps because those changes occurred after the standard biopsies were completed and treatment was initiated. — WP-Bloomberg