Early Stage Cancer Detection Hopes

"We're very, very excited and see this as a first step."
"But we don't want people to call up [to ask for the test to be conducted on them, since it is not yet available for clinical use]."
Nickolas Papadoppoulos, study leader, Johns Hopkins University

"It's such a good first set of results [giving hope this approach will succeed]."
"Anything close to fifty percent or forty percent detection is pretty exciting stuff [and this protocol succeeded even beyond that margin of success]."
Dr. Peter Bach, health policy expert, Memorial Sloan Kettering Cancer Center

"[If a blood test could find 98 percent of ovarian cancers at an early stage] that would be a significant advance [in screening success]."
"We have a long way to go to demonstrate its effectiveness as a screening test [however]."
Dr. Len Lichtenfeld, deputy chief medical officer, American Cancer Society

Researchers have created a blood test that could detect eight cancer types.

The most reliably successful investigative test yet devised for the presence of cancer cells remains the biopsy, an invasive test where a sample of human tissue must be drawn to allow for laboratory testing determining the presence or absence of cancer. The earlier in its formative stages that cancer is detected the more hopeful the outcome in striving to eliminate it. Scientists in laboratories the world over are hoping to succeed in their search for liquid biopsy tests that will perform that vital function.

And they are reporting some progress. As did the team whose study results has been published in the journal Science, where John Hopkins scientists attempted to determine how well their experimental test functioned to detect cancer in people known to have the disease. Blood tests succeeded in identifying roughly 70 percent of eight common types of cancer in the thousand patients who took part in this trial. An early result that proved to be rewarding in the extreme.

The liquid biopsy tests searches out DNA and other markers tumours shed into blood in an effort to find cancer before it has time to spread, past which time chances of eliminating the cancer may be compromised by its reach into many parts of the body. The test results reported on rendered a mere seven false alarms when tests on 812 other people without cancer took place. Rates of detection in those with cancer varied with specific types; lower detection for breast tumours, but higher for ovarian, liver and pancreatic tumours.

A radiologist examines mammography images in Wichita Falls, Texas. Breast cancer is one of the cancers the new blood test can detect. (Torin Halsey/Associated Press)

In some of these instances the test succeeded in narrowing the possible origin of the cancer to one or two areas, such as colon or lung; indicators whose importance lies in delineating how much follow-up testing a patient might require. Although the results are being hailed as close to a breakthrough, the test itself is not ready for use since it is required to be validated in a larger study. That larger study is already underway in a general population not comprised of cancer patients, to determine whether it does work to the extent hoped to help save lives.

The purpose of the test is to detect mutations in 16 genes associated with cancer. In the process it measures eight proteins which are often seen to be elevated in the presence of cancer. The test seeks out breast, colon and lung and five kinds of cancers for which screening tests are not yet available for people at average risk. That would include ovarian, liver, stomach, pancreatic and esophageal cancers. A blood test is already in wide use -- the PSA test -- for prostate cancer; a test whose screening value remains controversial.

The initial research was carried out on people whose cancers remained in situ, confined to where they began or had spread slightly, but not yet widely throughout the body. Success was measured in 33 percent of breast cancers, 60 percent of colon or lung cancers and close to all of the ovarian and liver cancers being detected. Success was more assured when tumours were larger or had spread; less proficient in detecting tumorous cancers at their very earliest stages.

A patient has blood drawn for a liquid biopsy at a hospital in Philadelphia. A study released Thursday showed promising results for a new blood test that detects eight cancers at an early stage. (Jacqueline Larma/Associated Press)