Chinese scientists announced on Sunday they had developed a method to measure the concentration of a cell protein that enables the detection of cancer with only a drop of blood.

The amount of the cell protein in a cancer patient exceeds that in a healthy body, they said.

Luo Yongzhang and his team at Tsinghua University identified heat shock protein 90 alpha (Hsp90 alpha for short) - an essential and ubiquitous protein in various cell types - as a "novel tumor biomarker." The team has also developed a quantitative detection kit for clinical use.

"Levels of tumor biomarkers increase in accordance with cancer progression. It has become a useful approach for disease monitoring and efficient evaluation," Luo said.

In 2011, the US National Cancer Institute listed 31 tumor biomarkers for tumor diagnosis worldwide. All were defined by scientists outside China. The protein is the first to be discovered by Chinese.

The validation of Hsp90 alpha was based on a series of scientific studies conducted by Luo's team since 2009.

In 2009, Luo and his colleagues reported the regulatory mechanism of the secretion of the protein by tumor cells, and revealed for the first time the molecular difference between its intracellular and extracellular versions of the protein.

They also found that the plasma level of the secreted protein in cancer patients is significantly higher than it is in healthy people, which showed the great potential that the protein has as a tumor biomarker.

Later, Luo and his team collaborated with biotech company Protgen Ltd to develop the Quantitative Detection Kit for Hsp90 alpha.

With the kit, only 10 microliters of plasma is needed to detect the level of Hsp90 alpha for disease monitoring and therapeutic evaluation.

"This is a much more convenient and cheaper method compared with other traditional means of tumor detection; for example, computed tomography," Luo said.

The kit was used in clinical trials in 2,347 cases in eight hospitals in China.

In April, this kit was approved by the China Food and Drug Administration as a third class medical device for disease monitoring and efficacy evaluation. Third class is the most rigorously tested type of medical device.

Later, it received European Conformity certification and ISO 13485 certification.

"Usually, doctors use multiple biomarkers to decide a patient's condition, because individual differences may impair their judgment. So the discovery of this new biomarker, Hsp90 alpha, offers a new option for doctors and patients," said Fu Yan, a research staff member of Luo's team.

The clinical trials showed the protein to be a useful tumor biomarker for lung cancer. More clinical trials for six different cancers, including liver cancer, breast cancer and colorectal cancer, have already started, Fu said.

"Very few of the known tumor biomarkers are specific for only one type of cancer, and there may not be any. As for Hsp90 alpha, it is sensitive to many cancers in theory, but we need to carry out more studies to find out."

Nobel Prize laureate James D. Watson sent his congratulations to Luo and was quoted in a media release as saying: "You and your colleagues in Tsinghua have made an enormous step forward toward conquering cancer."

chengyingqi@chinadaily.com.cn