Blood tests deliver cancer breakthrough

Is this the silver bullet? A simple new blood test can detect eight of the most common cancers long before they turn lethal.

The simple new blood test will be able to pick up early-stage tumours from proteins and genetic mutations circulating in the blood.

Scientists have created a blood test that can detect eight of the most common cancers long before they turn lethal, in a breakthrough that could save millions of people from premature death.

The “liquid biopsy” identifies early-stage tumours from proteins and genetic mutations circulating in the blood.

Trials have found that it can uncover fledgling cancers in about 70 per cent of cases, and up to 98 per cent for some types, long before they become detectable by other means. They include deadly conditions such as pancreatic cancer, which usually goes unnoticed until it has spread. The goal is to spot tumours before that happens, when survival rates are still high.

Dubbed CancerSEEK, the test delivers almost no false positives, sparing patients needless heartache and unnecessary medical procedures for non-existent diseases. It can also pinpoint ­tumours’ locations in about five cases out of six, paving the way for rapid treatment.

Outlined this morning in the journal Science, CancerSEEK was developed by an international team led by Johns Hopkins University in Baltimore. Three researchers from Melbourne’s Walter and Eliza Hall Institute contributed to the work.

 

WEHI professor Peter Gibbs, who also works as an oncologist, said the test was “groundbreaking” because it could hunt for ­multiple cancer types, including many for which no screening was available. “We see a lot of people with advanced cancer,” Professor Gibbs said. “If we could diagnose them early and prevent that happening, it would be wonderful.”

Professor Gibbs said pancreatic cancers did not trigger symptoms until they had grown quite large, and about 80 per cent were detected only at an incurable stage. The test can also pinpoint cancers of the liver, stomach, ovary, oesophagus, lung, bowel and breast. Population-level screening exists for only the last two conditions, such as mammograms for breast cancer and stool tests and colonoscopies for bowel cancer.

The only blood screen widely used for cancer is the controversial prostate-specific antigen test for prostate tumours.

Many doctors oppose it ­because of unacceptably high false positive rates, with three-quarters of men who are found to have ­elevated PSA levels later proving not to have cancer — often after painful and dangerous biopsies.

The new test boasts a false positive rate of less than 1 per cent. The research team trialled it on more than 800 people without known cancers, obtaining positive results for just seven of them.

“We could not be certain that (these) few individuals did not ­actually have an as yet undetected cancer,” the paper notes.

The test was also trialled on more than 1000 people with ­diagnosed cancer that had not yet metastasised. It successfully detected 33 per cent of breast cancers, about ­60 per cent of lung and bowel cancers, about 70 per cent of oesophageal, pancreatic and stomach cancers, and more than 95 per cent of liver and ovarian cancers. It also proved sensitive enough to pick up most tumours at stage II, when they had grown quite large but not yet spread. The test was able to detect all liver cancers at stage I, when they were still small.

The team says its likely price tag, less than $US500 ($630), compares well with the cost of screening tests for single types of cancer.

The researchers plan to explore its potential by trialling it on much larger groups of people without diagnosed cancer.

Some 10,000 US women have already been offered screening and follow up, with their outcomes to be compared with those from a control group.

While this could take years, Professor Gibbs predicted that CancerSEEK or something like it would become commercially available within a year or two — similar to private companies that now provide genomic screening.

“Someone’s going to start offering this sort of testing even before the results are in,” he said.