Biomarker for early diagnosis of lung cancer identified

Scientists have identified a potential noninvasive diagnostic marker that could change current practices in the detection and treatment of some types of lung cancer.

High levels of cytoskeleton-associated protein 4 (CKAP4) have been identified in the blood of patients with lung cancer.

In a study published in The American Journal of Pathology, researchers from Kitasato University in Japan found that CKAP4 levels were significantly higher in patients with lung cancer than in healthy individuals.

They further determined that CKAP4 levels are already elevated in the blood of patients with stage I disease.

This makes it a potential noninvasive diagnostic marker that could change current practices in the diagnosis and treatment of some types of lung cancer, including non-small-cell lung cancer and squamous cell carcinoma, and improve patient outcomes.

Lung cancer is associated with a poor prognosis because most lung cancers are only diagnosed at an advanced stage.

"The identification of patients at an early stage of cancer when it can be treated surgically is extremely important to improve prognosis," said Yuichi Sato from Kitasato University.

"We need better biomarkers for early diagnosis," said Sato.

Current biomarkers for lung cancer include carcinoma embryonic antigen (CEA), sialyl Lewis X antigen (SLX), and squamous cell carcinoma (SCC) antigen, but these are not sensitive enough to detect tumours early, said Ryo Nagashio from the Kitasato University School of Allied Health Sciences.

"The results of our study provide evidence that the CKAP4 protein may be a novel early sero-diagnostic marker for lung cancer," Nagashio said.

Researchers performed reverse-phase protein array analysis using a monoclonal antibody designated as KU-Lu-1 antibody on the blood of 271 lung cancer patients and 100 healthy individuals.

KU-Lu-1 reacted only with tumour cells and tumour stromal fibroblasts in lung cancer tissues and not with normal lung tissues, researchers said.

Using immunoprecipitation and mass spectrometry, they confirmed that the KU-Lu-1 antibody recognised CKAP4 in lung cancer cells and tissues, and its secretion into the culture supernatant was also confirmed.

In addition, a validation set consisting of samples from 100 patients with lung cancer and 38 healthy controls was also studied.