blood cancer types. A simple blood test detects eight types of cancer

 


A simple blood test detects eight types of cancer

A liquid biopsy technique that detects mutations and proteins associated with different types of cancer has proven to be much more effective than similar techniques developed recently, discovering the disease at an early stage. But to make it even more reliable, in view of potential clinical use, other experiments will be needed (red)
medicine
genetics
biology
The results of a preliminary study suggest that a single blood test could one day be used to detect different varieties of tumors.

The last few years have seen a series of experimental tests called liquid biopsies that promise to detect and localize tumors from a simple blood sample. Many of these tests are designed to detect a single type of cancer by identifying mutations associated with the tumor in DNA sequences circulating free in the blood.

The latest study, published January 18 in "Science", is unusual because it tests not only for these DNA mutations, but also for aberrant levels of some proteins, in an attempt to identify eight different types of cancer. The test was able to detect the disease in about 70 percent of over 1000 people who had already been diagnosed with cancer.

A simple blood test detects eight types of cancer
False-colored micrograph of ovarian cancer cells (Science Photo Library / AGF)
The researchers hope that eventually their work can lead to a simpler and cheaper test than the intensive sequencing involved in some other liquid biopsies. "They come to perform similarly to those of other methods, but with an approach that seems much cheaper," says Nitzan Rosenfeld, a research scientist at the University of Cambridge in the United Kingdom.

A needle in a haystack
Many groups in the academic and industrial worlds have focused on the use of liquid biopsies to monitor cancer progression and to guide physicians in the formulation of a treatment plan.

But the oncologist Nickolas Papadopoulos of the Johns Hopkins Kimmel Cancer Center in Baltimore, Maryland, and his colleagues wanted to develop a test that can detect tumors at an early stage when they are easier to treat.

Test
they are particularly demanding: usually small tumors do not release much DNA into the blood, as larger tumors do. And false positives are a problem for tests that need to be administered to large populations of healthy individuals: a wrong result can cause people excessive stress and lead to unnecessary and potentially harmful treatments.

Researchers looked for ways to make their liquid biopsy more sensitive, without increasing the risk of false positive results. The tests they developed - called CancerSEEK - examine the levels of eight proteins and the presence of mutations in 16 genes.

The group tested liquid biopsy on people already diagnosed with one of eight forms of cancer: ovarian, liver, stomach, pancreas, esophageal, colorectal, lung or sinus. And they excluded people whose cancer had spread to other parts of the body, so that they could concentrate on the early stages of the disease.

The effectiveness of CancerSEEK varied widely depending on the tumor: it detected 98 percent of ovarian tumors, but only 33 percent of breast cancer cases. He was able to identify the organ in which the disease had taken root in about 63 percent of the patients. But the test yielded better results on late-stage tumors than the early ones, finding 78 percent of stage III disease compared to 43 percent of stage I tumors.

Looking for sensitivity
Even so, these numbers are high enough to warrant further study, says Rosenfeld, who is also the scientific director of the Cambridge Inivata company, which deals with liquid biopsies. "Even if only half the tumors are identified, it's a great thing." It is not clear, however, if CancerSEEK is able to detect undiagnosed tumors, adds Rosenfeld

Another concern is that the rate of false positives may be higher in the general population, says Catherine Alix-Panabières, an oncology researcher at the University of Montpellier in France. Some seemingly healthy people may harbor inflammatory diseases that alter the levels of proteins detected by the test, he says.

It could take years to address these problems. But researchers have already started a study that will test CancerSEEK in at least 10,000 healthy individuals, says Papadopoulos, who worked as a consultant in a liquid biopsy company called Personal Genome Diagnostics, based in Baltimore, United States. The researchers plan to follow those volunteers for five years.

In the meantime, other research groups are expected to perfect their liquid biopsies by combining DNA sequencing with other blood tests, says Alberto Bardelli, an oncologist researcher at the Candiolo Cancer Research and Treatment Institute in Turin. . "This study is provocative," he says. "It emphasizes that we should stop looking at a small part of the overall picture: we need to consider all sources of information in the blood".