Johns Hopkins scientists have developed a blood test that can detect tiny amounts of DNA from four cancers, a breakthrough that has the potential to catch those cancers early enough to reduce the number of deaths.
The scientists with the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center say they have used the test to detect early stages of colorectal, breast, lung and ovarian cancer in dozens of patients.
The blood test is one of many in early development being tried to diagnose and treat cancer earlier. The Hopkins researchers say their test is different because it detects the DNA directly from the blood.
The Hopkins scientists' test could identify the cancers before people usually are diagnosed. This could be crucial for improving the survival rates for ovarian and colorectal cancers, which typically are found in later stages when treatment is not as successful, said Dr. Victor Velculescu, a professor of oncology and co-director of cancer biology at the Kimmel cancer center.
More than 14 million people globally are diagnosed each year with new cancer cases. Many who die from the disease do so because of late diagnosis when treatment is less effective, various research has shown.
"The survival difference between late and early stage diagnosis is extremely significant if we can detect and intervene early," Velculescu said.
The scientists used blood samples from 200 patients with various stages of cancer, according to a report on the findings recently published in the journal Science Translational Medicine. The patients lived in the United States, Denmark and the Netherlands.
The test was able to accurately diagnose cancer DNA in the blood of 62 percent of 138 people with early stage cancer. In the 42 people with colorectal cancer, the test predicted cancer in half of the patients.
Velculescu said the test could be most beneficial to people at high risk for cancer, including smokers. He noted that scans used to detect lung cancer often result in a false positive diagnosis. Women with a genetic disposition for breast or ovarian cancer could benefit too.
Dr. J. Leonard Lichtenfeld, deputy chief medical officer with the American Cancer Society, said research on blood tests for cancer has advanced significantly in the last several years.
"The next step is to be able to find the cancer before it is detected," Lichtenfeld said. "They seem to be as close if not closer than other groups to making this a reality."
Dr. Kevin Cullen, director of the University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center, said the blood tests is one of the most advanced he has seen. He also said they reported no false positives, which is a positive outcome.
A weakness in the study is that the test did not catch enough cancer cases, Cullen said. The test found stage 1 colon cancer in 50 percent of patients, breast cancer in 67 percent, and ovarian cancer in 67 percent. Cullen said an 80 to 90 percent detection rate would be more ideal.
"I think the bad new is they missed a lot of the cancer that was there," he said. "They were only able to detect between 60 to 80 percent of cancer. That is probably too low of a sensitivity rate to use as a screening test."
The Hopkins researchers said the blood tests would need to be further validated in larger studies using more people.
Velculescu also said any blood test would complement, not replace, other traditional tests.
"This testings isn't going to replace all of the other important tools we have in medicine," he said. "Anybody with a positive test would be further tested and analyzed to determine where in the body the tumor would be coming from."