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Blood Test Can Detect Cancers in Previously Undiagnosed Women

DNA helix in test tube of blood illustration
The "liquid biopsy" looks for tumor DNA and cancer-related proteins in blood. | iStock

Researchers have shown for the first time that a blood test can be used safely to detect multiple types of cancer in women with no previous signs of the disease.

In a clinical trial of 9,911 women with no evidence or history of cancer, the blood test or "liquid biopsy" detected 26 of the 96 cancer cases identified during the trial. Scientists uncovered an additional 24 cancers among the group using traditional screening methods like mammography, according to the study published April 28 in Science.

Among the 26 women who had their cancers first detected by the blood test, 65% were diagnosed at an early stage of their cancer. Twelve of the women are now in remission after treatment, and eight remain in treatment or have their cancer stabilized nine months after their diagnosis.

"This study suggests that a multi-cancer blood test can be complementary and additive to standard of care screening and may be a good strategy for increasing early detection of cancer," said Anne Marie Lennon of Johns Hopkins University School of Medicine, the study's lead author.

Breast, lung, thyroid and colorectal cancers were among the 10 types of cancers detected by the blood test screening. In all, 16 types of cancers were identified in the study participants. The researchers enrolled only women because they wanted to be sure ovarian and uterine cancers were sufficiently represented the study.

Ovarian cancer, like several other malignancies detected in the study such as lymphomas, lacks a traditional screening test like those used for breast and colorectal cancer. Patients respond better to surgery, radiation and immunotherapy if cancers are caught when they are small and confined to one area of the body, however, so clinicians have turned to blood tests as a way to find multiple cancers at an early stage.

The multi-cancer blood test used in the current study is an earlier version of the CancerSEEK liquid biopsy system described by Lennon and her colleagues in 2018 in Science. It detects cancer by looking for pieces of tumor DNA and measuring levels of cancer-related proteins in circulating blood.

Women who had signs of cancer detected in their first blood test had a second blood test to confirm that that the abnormal result was consistent. After a committee examined their tests and medical records to rule out any non-cancer reason for the abnormal blood tests, women received a full-body diagnostic PET-CT scan to confirm the cancer's presence.

The scan also helped the clinicians fill in the details about the cancer, said Johns Hopkins researcher Nickolas Papadopoulos. "For example, we could detect a lung cancer, tell in which lobe of which lung the cancer was located, the size of the cancer and if there were metastatic lesions present. Blood tests alone are not able to provide this type of precise information."

The blood test screening did not lead to a significant number of unnecessary procedures, the researchers concluded. Only 1% of the women had false positive blood tests that sent them on to further screening with the PET-CT scan, and 0.22% of the study's participants with a false positive blood test had an invasive diagnostic procedure like surgery.

The study also followed women after their first blood test to see if they might be less likely to go for traditional cancer screenings if their liquid biopsy turned up no signs of cancer. Instead, the researchers found that the group of women were undergoing mammograms at about the same rates as before the study.

This finding was gratifying to the researchers, they said, as they noted that the liquid biopsy should complement but not replace traditional screening.

"We believe that more than two-thirds of cancers that occur in the U.S. can eventually be screen-detected, either by blood testing or standard screening, before they cause symptoms of disease," said Bert Vogelstein, a Johns Hopkins senior author on the Science study. "Such earlier detection has the capacity to substantially reduce suffering and death from many cancer types."