A test that scans blood for tumour-specific DNA identified early-stage cancer in more than half of 138 patients with the disease, United States researchers reported on Wednesday, marking a new milestone in the rush for so-called "liquid biopsies".
Note that the study adds to the growing volume of information about "liquid biopsies" for cancer diagnosis and other potential applications in cancer management.
Researchers behind the early-stage test hope it could be used to identify cancers at a stage when patients have a better chance at survival.
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 survival difference between late stage and early stage disease in these cancers would account for more than a million lives each year worldwide", Velculescu said.
Acknowledging that "a lot of work in liquid biopsies in general" is ongoing, Velculescu pointed to distinguishing features of the study.
Cancer patients had more of this DNA in their blood, the team found. "There are a number of confounding errors that can come up". The genes were sequenced in 100 of the patients and 82 of them showed the same mutations in blood samples as well as in the tumour tissue samples. It was even more accurate in finding late-stage cancers, but the goal would be to catch cancer in its earliest, easiest-to-treat stage.
Many well-established cancer biomarkers also occur in the absence of cancer - such as cancer antigen (CA) 125, CA-19, carcinoembryonic antigen, and prostate-specific antigen. These pieces are called cell-free circulating tumor DNA (ctDNA).
A team of oncologists at Johns Hopkins Kimmel Cancer Center found that dying tumor cells release small bits of their DNA into a sufferer's blood which can be tested.
Investigators analyzed plasma samples from a total of 194 patients, consisting of 45 patients with breast cancer, 42 with colorectal cancer, 65 with lung cancer, and 42 with ovarian cancer. These were untreated patients who had localized or metastatic disease at stages I and II.
Each blood sample was screened with a panel of 58 genes commonly associated with a variety of cancers. While concentrations of cfDNA were average of 7 ng/ml in healthy participants, it was around 29 ng/ml in cancer patients. The detection rate increased into the 90s for the later stages of tumors, based on the tumor type, the results show. In the colorectal subgroup, the test predicted cancer in four of eight patients with stage I disease, eight of nine with stage II disease, nine of 10 with stage III, and 14 of 15 with stage IV.
To check the blood test's ability to weed out healthy people, the researchers also analyzed blood from 44 volunteers without cancer.
A new Johns Hopkins study outlines a potentially game-changing screening methodology to catch some of the most common cancers at their earliest stages.
Scientists at King's College London think the new imaging technique will allow them to identify women whose cancer is likely to spread into their lungs, allowing them to use intensive treatments earlier to stop the spread.
The study was supported by the NIH and multiple philanthropic, nonprofit, and governmental sources.
Velculescu disclosed relevant relationships with Personal Genome Diagnostics and Ignyta, as well as patent/royalty interests.