Liquid Biopsy: When a Simple Blood Test Can Cause Cancer – 06/16/2022

Imagine for a second you were transposed into the karmic driven world of Earl. When I got the result my stomach butterflies would increase, but given the golden chance of receiving early treatment and overcoming the disease, it would be good.

Some say that sooner or later this will be our part make sure. And the idea is not far off. Today, there are already three laboratories in the United States that offer this option, which promises to catch at least 20 common types of malignant tumors.

But the so-called liquid biopsy would not lose one case or another, that is, when the cancer is very early, let us fully trust that there is still a long way to go.

For now, by doing this, half of the people with childhood cancer may receive a negative result because they have found no malignant cells in the plasma or, better yet, because no genetic material has been found. liquid part of the body.blood. And, of course, this does not mean that the disease does not exist.

“This test is much more effective when metastasis is already present,” said Gabriela Félix, a Bayonne biomedical physician and manager of the Brazilian oncology laboratory Igenomix.

It makes sense for liquid biopsies to work better in the more advanced stages of this disease: “Tumors always give small parts,” Gabriela explains, in a simple way. “And that happens with more intensity when he’s very active.” Read on, when it spreads.

Needless to say, if the cancer has already spread, there are more foci of it throughout the body, so finding a little more of these molecular tendencies is abandoned in the blood plasma, which makes it easier.

“It’s mainly because these diseased cells or parts of their DNA aren’t left in the circulation forever,” says Gabriela. “They break the liver and expel the kidneys.” This is even more confusing when the quantity is not large.

But in addition to this complication of the quantity, as all the cancer is soaked in blood, the plasma tends to drag all its secrets. “The exception is some tumors where we can’t find enough signs in the blood sample. No one knows why. And then you have to look for other fluids as an alternative.”

This is the case, for example, with brain tumors: it is often more productive to take spinal fluid samples. Understanding what happens to a bladder tumor can be much more helpful in urinating.

If the role of liquid biopsy in diagnosis continues to be a hotly debated topic, the reality is that it has other applications in cancer monitoring and treatment, where it is able to make a complete difference. Of course, this is not the case.

To choose the best treatment

Let it be clear that the usual biopsy, which is a procedure to remove a part of a suspicious tissue, remains the gold standard for the study of cancer genetics. But sometimes that is not enough. And this gave way to liquid biopsy, which was only used in the first study, in clinical practice.

“In lung cancer, the usual medical examination is done through a thin needle inserted into it to aspirate a portion of the tissue,” says biologist Gabriel Macedo, director of precision oncology at Igenomix Brazil. “The problem is that with every aspiration of the needle only a small tissue comes out, and in the end the sample can be very small. That’s why, between 20% and 30% of the time, we don’t do it.” I don’t have enough tumor DNA or sequencing. “And it would be more important than ever in lung cancer.

In recent years, cancer treatments have become increasingly personalized, able to act correctly when one cancer has this or that specific genetic variant. And probably no other tumor has gotten as many new therapeutic options as lung cancer. “We only need genetic testing to find out what the best indication would be,” the biologist explained, taking two blocks the size of matchbox boxes for me to see.

In such blocks, made of paraffin, the tissues extracted from old biopsies are preserved. In one of them, I see a big dark spot. “By extension, I know this isn’t lung cancer,” says Gabriel Macedo, who then shows me a second paraffin box where I can see almost nothing inside. “This looks like a lung sample, and the first bottleneck is that the pathologist will already use a good amount of the small tissue here, leaving even less for genetic testing.”

With almost nothing left, oncologists can go for a liquid biopsy. This was the first FDA approval, by the way, in 2015 to prevent this difficulty in genetic testing for lung cancer and to answer which of the new drugs would be the most effective.

To explain why the disease has returned

Sometimes, after a year of rest, lung cancer reappears. “We need another genetic test to understand the reason,” says Gabriel Macedo. “The patient, who is a disease-causing organism, may be too weak to have a regular biopsy, so we are bleeding.”

In six out of ten, there is a mutation known as T790m, which makes this cancer resistant to the treatment used so far. “Liquid biopsy shows whether there is such a mutation, and that is valuable because there is already a drug. T790m and by using it you prolong the life of the individual. ‘

To reduce wasted time

Even when someone gets rid of cancer very early on, there may be what doctors call residual disease, which no one saw.

In March of this year, for example, scientists at the University of Cambridge in England published a study of 88 patients who found a lung tumor very early and underwent surgery with the firm aim of ending it. account ..

But either way, everyone continued with the liquid biopsy. “The result was an average of 200 days before he was diagnosed with cancer,” says Gabriel Macedo. “Early identification allows us to act earlier, increasing our chances of success.”

This, then, is another indication that after a medical treatment, a liquid biopsy can be performed on the patient every six months.

In a tumor that spreads from the bones

Two years ago, drugs called PARP inhibitors were approved that are able to benefit 28% of men with prostate tumor metastasis. “But here’s the thing: 40% of genetic testing with tissue samples will fail without showing who would benefit from using these inhibitors.”

This is because prostate cancer often reappears in the bones. “And there’s nothing more difficult than performing a DNA test to extract DNA from a bone sample,” said Gabriel Macedo. “This is another scenario where liquid biopsy would gain strength.”

Wouldn’t the same thing happen in other tumors with bone metastases? “Yes, in principle,” replied Macedo. “I can do a liquid biopsy of any tumor. I have to be careful with a negative result, because it doesn’t necessarily mean that the person I was looking for has not changed. It may not have been easy to find. In the blood.”

To complete the traditional biopsy

There are those who say that a liquid biopsy can be even better than usual in ovarian cancer. More research is needed to spread this claim. But the fact is that some mutations in the famous BRCA 1 and BRCA 2 genes are not always detected in ovarian tissue samples.

“A mutation never appears in the whole tumor, as if its cells were empty clones,” explains the director of Igenomix. “It can focus on a small part and the biopsy unfortunately takes on another piece.”

The blood plasma, on the other hand, drags everything in the tumor a little; it doesn’t have that history of the right piece, the wrong piece. Therefore, it is always possible to complete the first exam.

To see who is at greatest risk

Finally, although about 49% of early tumors escape fluid biopsy, in some situations it is better to do so than not to do so.

It may be advisable to ask every six months for those who smoke, for example. Well, no one sent this guy to repeat the image exams during this time. It is easier to draw blood.

“It’s the same for people at risk for hereditary cancer, which is 10% of all tumors,” says Gabriel Macedo. In the south and south-east of the country, for example, one in 300 people has what is called Li-Fraumenti syndrome, which is caused by a defect in the TP53 gene, which is thought to be a suppressor of cancer.

Without a perfect condition, a person has a 50% chance of getting a malignant tumor before the age of 30. Until recently, the only way to monitor this risk was to perform a full-body resonance. But there you have it: people with this syndrome are also very sensitive to radiation, and in their case, they may be even more likely to develop cancer. Not surprisingly, again, the alternative here could be blood tests.

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