Although many dread the prick of a blood test, most would find it a preferable testing method to invasive and expensive biopsies. That's why a blood test for cancer is the goal of many research efforts, including one at the University of Bradford in the UK, where researchers are claiming to have devised a simple universal blood test for the disease that relies on the fact that white blood cells in cancer patients are already damaged from battling cancerous cells.

"White blood cells are part of the body’s natural defense system," says Professor Diana Anderson, who led the research. "We know that they are under stress when they are fighting cancer or other diseases, so I wondered whether anything measurable could be seen if we put them under further stress with UVA light."

To put her theory to the test, the University of Bradford team used a comet assay, which involves exposing DNA to UV light and applying an electric field to induce it to travel through an agar medium. The more damaged the DNA, the more elongated its comet-like tail, as the structure is no longer as tightly compressed together.

"We found that people with cancer have DNA which is more easily damaged by ultraviolet light than other people," says Anderson. "So the test shows the sensitivity to damage of all the DNA – the genome – in a cell."

The research team was able to compare the results of the test between patients confirmed as having one of three cancers – melanoma, colon cancer, and lung cancer – patients suspected of having cancer, and healthy patients. The DNA of healthy samples approached control values, while values of precancerous and suspected cancer patients were intermediate between healthy samples and that of confirmed cancer patients.

Anderson points out that, while the initial sample size is small (208 combined samples), the statistical analysis of the results suggests that this could be an accurate diagnostic tool, either alone or in combination with other procedures.

The Bradford Royal Infirmary is hosting clinical trials with patients referred by their family doctors for potential colorectal cancer. The comet assay technique will be used to identify which patients would benefit from a colonoscopy, the usual next step in diagnosis. A colonoscopy usually takes one to three hours, and a day off from work, so would be improved upon by specifically targeting those who would benefit from the diagnostic.

The results were originally published in The FASEB Journal.