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A blood test that detects cancer without symptoms could be a gamechanger for Louisiana

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Date: 2022-09-22 23:31:56

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Within a dozen patient blood draws, Dr. David Myers, an internal medicine physician in Metairie, got the first positive result for a new blood test that detects cancer last summer.

A healthy patient in her 60s had a marker that indicated she may have a type cancer related to HPV, or human papillomavirus. After some detective work and looking closely at her lungs and throat, they found a two-centimeter squamous cell Stage 2 anorectal cancer. She was treated and is now cancer free.

Had symptoms in later stages flagged the cancer, the results may have been less favorable. Stage 3 anorectal cancer has a survival rate of 50%. At Stage 4, it drops to 30%, said Myers.

“In her case, it was life-saving,” said Myers, who has given the test to about 115 patients who are members of his concierge-style practice.

By the time troubling symptoms lead to a cancer diagnosis, the outlook is often bleak. That is especially true in Louisiana, where more people die of cancer than nearly anywhere else in the U.S.

Screenings like mammography, pap smears and colonoscopies offer some diagnoses, but many in Louisiana find out about cancer late, and later diagnoses disproportionately affect Black people in the state. A bevy of new tests, including the Galleri test that Myers uses, might offer a faster diagnosis, allowing cancer to be treated earlier.

As tests like this — known as liquid biopsies — show more promise, clinical trials in Louisiana that will offer the test to participants free of charge are ramping up.

What is it?

The technology for the Galleri test was born out of the same type of blood tests that flag chromosomal abnormalities like Downs syndrome and Trisomy 13 and 18 in pregnant women. Like a developing fetus, cancer sheds fragments of DNA into the bloodstream.

The minuscule pieces of cancer DNA are wrapped in methyl groups, like an electrical wire wrapped in a rubber cord. The test looks at the way the DNA is wrapped up and identifies the type of cancer by comparing it to an ever-growing database of known cancer methylation patterns.

Last week, Grail, the company that produces Galleri, released results from a clinical trial called the Pathfinder study that detected dozens of new cases of cancer in around 6,600 adults over the age of 50. Nearly half were found in early stages and 71% of the newly detected cancers were types that are not typically screened for, such as ovarian and pancreatic cancers. 

In the study, 92 of the 6,621 patients who were tested were flagged with potential cancer. Additional testing confirmed cancer in 35 people — about 1.4% of the initial group.

The downsides

Although scientists are optimistic about the tests and dozens of companies have invested in developing the tests, there are potential drawbacks.

The test misses two fatal cancers 100% of the time: early-stage melanoma, because the skin cancer cells are flaking off the body rather than in the blood, and brain cancer, Myers cautioned.

“It gets all the other big nasty cancers – the things we have no way of screening for that everyone is scared of,” said Myers.

The test is also not meant to give the all-clear for cancer status. Dr. Margaret Pelitere, a New Orleans-based internal medicine physician, recommends it, but still has patients do the standard screening tests.

“I think statistically, this is a very good thing to have,” said Pelitere, who has had one patient test positive, likely for lymphoid cancer, out of 32 tests she’s given. “But this does not replace other cancer screenings, such as colonoscopy and mammogram.”

During a year-long follow-up of the 6,662 Galleri trial patients, 29 cancers were identified in routine screenings that were not flagged by the test, and another 56 cancers were diagnosed after symptoms appeared or tumors were found incidentally or from monitoring for cancer recurrence.

There are also false positives. In the recent trial, 38% of the positives were correct. However, the false positives still made up a small proportion of the total study group. And the rate of false positive is by design, said Myers.

“These tests are powered to capture a lot of positives,” said Myers. “We want to not miss stuff.”

Then there is the cost. A test is around $950, and it’s recommended annually. Insurance does not cover it.

“There is no way for probably 80% of the residents in Louisiana to afford it,” said Tony Ye Hu, director of Tulane University’s Center for Cellular and Molecular Diagnostics. Hu’s work focuses on identifying biomarkers for cancer and infectious diseases, and he is also researching a liquid biopsy test to detect pancreatic cancer.

But pointing to the much-lowered cost of COVID tests over the last two years as an example, Hu said political will can lower the cost of testing, especially if use is widespread.

Galleri is not currently approved by the FDA, but a bipartisan bill has been introduced that would require liquid biopsy test coverage for Medicare once it is. If the cost remains the same, covering Louisiana’s 900,000 Medicare patients – about 20% of the state’s population – would be around $900 million. 

As of now, there is no data showing that widespread liquid biopsy screenings would lower the risk of death.

“You have to run very large trials to show that is beneficial to the population,” said Dr. Pedro Barata, a former Tulane University oncologist who uses liquid biopsy to determine treatment for existing cancers. Screenings like colonoscopy and mammography are recommended at certain ages because they are proven to save lives.

Doctors agree that it’s not an ideal test for every patient, especially if they have a poor outlook from other diseases or are elderly. And some slow-growing cancers such as prostate cancer, hormonally sensitive breast cancer and some thyroid cancers don’t necessarily need aggressive treatment.

“For some people, treating a disease early doesn’t always mean a good thing,” said Barata. Some cancers don't progress to a worrisome point, and in those cases the cure — painful drugs that wipe out the body's defenses — may be worse than the illness. 

Despite those concerns, most agree that the blood tests will become more of a standard detection tool in the future as artificial intelligence learns the distinct patterns of different types of cancers.

“It’s going to get better all the time. The test is learning,” said Myers. The blood specimen of the patient with anorectal cancer has been added to Galleri’s database, so others with similar patterns can identify cancers faster.

More clinical trials

About 480 total patients have taken the Galleri test in Louisiana, according to the company, though that does not include people in some large trials or any of the other blood tests for cancer on the market.

Ochsner Health has entered into a partnership with Galleri and is enrolling 1,000 patients over the age of 50 in New Orleans and Baton Rouge into Grail’s Pathfinder 2 study, a follow-up study that will track patients for three years, according to Dr. Marc Matrana, medical director of precision cancer therapy at Ochsner.

Ochsner is also enrolling 7,500 people in another study called the Reflection study, which will track how the Galleri test affects the health outcomes of high-risk patients with low socioeconomic status who typically don’t have good access to health care.

Of the few dozen patients at Ochsner who have opted to pay out of pocket for tests so far, Matrana has seen one positive result. In the future, he expects the test will just be part of a standard workup with a preventative care doctor. 

"Our prediction is that as the years go on, pretty rapidly, these tests are going to be just part of the way we practice medicine," said Matrana. 

Original Source: https://www.nola.com/news/healthcare_hospitals/article_d69f0fea-39cb-11ed-8c04-4f0d092e01d5.html