A New Blood Test for Breast Cancer Can Detect Earlier Than Mammograms

The study's findings were published in July 2022 in the journal Cancers, based on data gleaned from a group of more than 10,000 women, 548 of whom had breast cancer. The test detected breast cancer with 92 percent overall sensitivity, a success rate that's an impressive five percentage points better than the rate for mammograms.

"The specificity is very good, in other words, the absence of false positives," said Timothy Crook, Ph.D., M.B.B.S., a medical oncologist based in London who was one of the study's authors. "And then we come down to sensitivity: how many positives does it pick up, and we're well into the 90s [percentile]. It will probably depend on demography, different populations, and it needs validation in real-world trials, but the sensitivity and specificity are exceptionally promising."

The blood test Crook and his team researched was developed by Datar Cancer Genetics. In 2021, the U.S. Food and Drug Administration (FDA) granted the test breakthrough status, meaning it shows lifesaving potential. It works by identifying tiny particles called breast adenocarcinoma-associated circulating tumor cells (BrAD-CTCs), which tumors shed into the bloodstream.

Even very small amounts of CTCs were detectable using the new technology. Not only that, the test can determine exactly what type of cancer is present.

"The origin of those abnormal cells can frequently be identified right down to an organ-specific level," Crook said. "And they've got a set of markers for breast. So if you're using the breast platform, then any cells that are found in a person being screened will then be subjected to a second level of analysis to ask if these are breast cancer cells."

This means breast cancer may be detectable using just a few drops of blood, potentially reducing the need for having your breasts mashed between two plates and X-rayed, at least as a first-tier screening.

"Mammography is a particularly clunky and cumbersome way to be health-screened," Crook said. "Firstly, you're medicalized, aren't you? You feel like a patient. The obvious thing is the discomfort, and the other thing is even though it's a safe modality, I think a lot of women don't want to have their breasts irradiated. Clearly, it's safe doses. But if you've got no radiation with comparable sensitivity and specificity, the no-radiation platform is a lot better."

The blood test goes even further in terms of specificity, overshadowing standard mammography in many ways.

For starters, it hit the aforementioned 92-percent mark overall in detecting breast cancer, beating out mammography by five percentage points.

But drilling down further into the numbers yields some amazing details. For one, the test accurately identified 96 percent of the women who had stage 2 breast cancer and 100 percent of those with stage 3 or stage 4 cancer.

Incredibly, researchers were also able to detect 89 percent of stage 1 cancers and 70 percent of stage 0 cancers, a stage that signifies precancerous lesions that could potentially develop into cancer.

"The company has unique methodology which allows this high sensitivity because it protects the integrity of the cells that are circulating in the blood," Crook explained. "Some platforms which have looked for circulating tumor cells, they tend to be quite impactful on the structural integrity of the cells, therefore, reducing the yield and sensitivity."

Given those numbers, researchers are hopeful that once the test passes real-world trials and can be adopted into widespread use, it could help detect breast cancer and precancerous lesions in younger women long before they typically begin recommended regular screenings.

The promise of an accurate and simple-to-use test for breast cancer is a great stride forward that rivals the rosiest science fiction.

But the technology isn't limited to just breast cancer. The company is working toward validating tests for more than a dozen different types of cancer, including pancreatic, lung, ovarian and prostate.

Crook and his team envision a time in the foreseeable future when a single annual blood draw would screen for an array of cancers.

"I think it will be widely available within single-figure years, less than five years," Crook said. "The really big thing is going to be when national health systems adopt this instead of imaging, or for prostate cancer. We have the PSA, which is not very specific. There are all sorts of causes [for elevated PSA values]. Lots of patients have an intermediate range that doesn't really tell you what's happening. So I think those are going to be replaced by blood-based platforms within the next five years. That's my guess.

"I may be overoptimistic," Crook added. "I may be overidealistic, but to me, that's definitely going to happen."