Developing a blood test that can detect cancer has been a major area of research for scientists in recent years. Early detection is key in helping doctors successfully treat the disease and a blood test would be far simpler than invasive biopsies. Researchers at Purdue University recently made a major breakthrough identifying a series of proteins that, when found in elevated levels in a patient's blood, can signify the presence of cancer.

In the past, researchers have looked at numerous types of biomarkers found in blood to discover new ways to detect cancer. One study looked at the RNA profiles of blood platelets, while another examined the DNA damage in white blood cells.

There are several challenges faced by scientists in developing a blood test for cancer. On one front there are so many types of cancers that finding specific biomarkers that cover a broad range of cancers has proven difficult. It's also quite challenging to confidently correlate the raised levels of specific biomarkers as indicative of the presence of cancer. Sometimes certain biomarkers can be naturally high in patients or be a result of a different abnormality.

A research group at Purdue University led by W. Andy Tao initially identified a process called protein phosphorylation as a prime candidate for cancer biomarkers. The process involves the addition of a phosphate group to a protein that is known to lead to cancer cell formation.

Before this research, scientists were not sure it would be possible to clearly identify levels of phosphoproteins in blood, because the liver releases an enzyme into the blood that removes phosphate groups from proteins. But the Purdue team found success with a new process that can analyze the levels of hundreds of different phosphoproteins in blood samples.

"This is definitely a breakthrough, showing the feasibility of using phosphoproteins in blood for detecting and monitoring diseases," Professor Andy Tao said.

The team compared small blood samples from 30 patients with breast cancer against six healthy control group samples. They not only isolated nearly 2,400 different phosphoproteins, but also identified 144 that were found to be significantly elevated in the cancer patients.

The most groundbreaking aspect of the research is that this broad set of biomarkers can be used to identify all cancers as they are fundamental to the development of cancer tissue. The researchers are now shifting their focus to looking at the levels of phosphoproteins in different types of cancers to see if there are patterns that could allow the tests to determine which specific type of cancer a patient has.

As well as helping an initial diagnosis, this research could pave the way for a simple blood test that can monitor patients in remission, allowing for quick identification and treatment if the cancer returns.

The team's research has been published in the journal Proceedings of the National Academy of Sciences.