New tumour marker identifies early-stage gastric cancer

Researchers from Nagoya University have discovered that the stromal cell-derived factor 4 (SDF4) protein is a reliable cancer marker that can be accurately identified in simple blood tests, suggesting its potential use for the early detection of gastric cancer. Their work has been published in the journal Scientific Reports.

Gastrointestinal cancers, such as oesophageal, gastric, colorectal, liver and pancreatic cancer, are often found too late for effective treatment. A suitable marker, or biological substance that shows the existence of a tumour, is therefore needed to help doctors to find, diagnose and monitor cancer and treatment. Performing cancer therapy at an earlier stage achieves more favourable results and increases the survival rate.

“Currently, blood tests to detect cancers, such as gastric, colorectal and breast cancer, have used tumour markers like CEA and CA19-9,” said Dr Takahiro Shinozuka, the first author of the study. “However, these tumour markers do not always accurately detect all cancers, and their accuracy needs to be improved.

“Other markers have been proposed but have drawbacks — such as intricate, costly measurement procedures or invasive testing methods — that prevent their use.”

Looking to create new tumour markers to detect different types of cancer at an early stage, Shinozuka and colleagues investigated proteins secreted by cancer cells and identified SDF4 as a useful candidate. When they measured the concentration of SDF4 in blood samples from cancer patients and healthy individuals, they consistently found elevated levels in cancer samples, including those taken from gastric, oesophageal, colorectal, pancreatic, breast and liver cancer patients.

In cancer diagnosis, sensitivity and specificity are important. Sensitivity shows how well the test finds the disease in sick patients, whereas specificity shows how well it finds the disease in healthy patients. Testing their protein, the group found that it had a sensitivity of 89% and a specificity of 99%, far exceeding the sensitivity of conventional tumour markers (13% for CEA and 17% for CA19-9) in identifying cancer patients. The protein was found in high levels even in patients with stage I gastric cancer, suggesting that it may be able to detect cancer before symptoms show.

“There are two ways in which SDF4 outperforms conventional tumour markers as a diagnostic marker,” Shinozuka said. “The first is that it can diagnose patients with early-stage cancer and the second is that it is useful as a diagnostic marker for various types of cancer.

“We are working with a company to develop measurement devices that can be used for cancer screening. If these efforts are successful, we hope to introduce SDF4 into actual cancer screening, helping in the early detection of cancer.”

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