Scientists develop test that could detect cancer before symptoms show

Henrietta Strickland
August 17, 2017

For example, there is a chance cells will acquire mistakes or mutations and in a small fraction of people, these changes will spur a blood cell to multiply faster than its neighboring cells, potentially leading to pre-leukemic conditions.

A blood test that distinguishes tumor DNA from altered non-tumor DNA detected cancer-related mutations in more than half of patients with early-stage malignancies, an worldwide research team reported.

"The challenge was to develop a blood test that could predict the probably presence of cancer without knowing the genetic mutations preset in a person's tumor", said Victor Velculescu, the corresponding author of the work, who is a professor of oncology at Johns Hopkins' Sidney Kimmel Comprehensive Cancer Center.

The most hard part in using this test for detection was to enable it to identify the rare DNA from cancers and not showing up results from other types of genetic alterations or mutations that a person is born with or develops during life.

In the subgroup of patients with resectable colorectal cancer, higher preoperative levels of circulating DNA correlated with disease recurrence and worse survival, they reported in Science Translational Medicine.

The method involved sequencing DNA over 30,000 times to look for alterations in DNA from tumor cells that float in the blood.

Red blood cells
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Just by looking at their blood, the researchers were able to identify 62 percent of the people with stage one cancer, fifty percent of the overall colon cancer patients, and 90 percent of the colon cancer patients with stage two, three or four.

The doctors identified more than three-quarters of colorectal cancer patients, two-thirds of ovarian cancer patients, and most of the lung and breast cancer patients, who exhibited detectable alterations in driver genes. But for him, the astonishing fact is that this blood test could make them detect more and number of early stage patients having blood alterations. Development of noninvasive ways to identify cancer in early stages of development has proven challenging. They noted 58 genes that are typically associated with these cancers. This library of genetic sequences is then captured and sequenced for analysis. The total study population included 138 patients with stage I or II disease. Samples were processed within 2 hours from collection from the healthy individuals. While concentrations of cfDNA were average of 7 ng/ml in healthy participants, it was around 29 ng/ml in cancer patients.

The test also needs to be tried on larger numbers of patients and on patients with more obscure cancers.

Of 71 people with lung cancer, the test found 45% with stage I disease, 72% with stage II disease, 75% with stage III disease and 83% with stage IV cancer.

Velculescu said the next steps for the test will be to expand the investigation to include more patients, and with different tumor types, and to conduct clinical trials to determine the impact of early detection on clinical outcomes. Liquid biopsies were used to detect the return of cancers after treatment.

The study was supported by the NIH and multiple philanthropic, nonprofit, and governmental sources. One or more co-authors disclosed relationships with Personal Genome Diagnostics, Merck, and Cell Design, as well as patent/royalty interests.

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