May 8 (UPI) -- High levels of a protein found in the bloodstreams of lung cancer patients may lead to a method of detecting the disease earlier, and possibly preventing deaths from it, according to a new study.
Researchers found high levels of cytoskeleton-associated protein 4, or CKAP4, in the blood of cancer patients predicted their disease. The research was published Tuesday in the American Journal of Pathology.
Lung cancer is the leading cause of cancer death in the United States, and the second-most diagnosed cancer in men and women, according to the Centers for Disease Control and Prevention.
Most lung cancers are diagnosed at an advanced stage and the prognosis is poor. The five-year survival rate for stage 4 non-small cell lung cancer, when the cancer may have not have spread through to nearby structures, is about 10 percent. For stage IV -- when cancer has spread to more than one organ -- the rate is less than 1 percent, according to the American Cancer Society.
"The identification of patients at an early stage of cancer when it can be treated surgically is extremely important to improve prognosis," Yuichi Sato, a researcher at the Kitasato University School of Allied Health Sciences in Japan, said in a press release. "We need better biomarkers for early diagnosis."
The previous biomarkers -- carcinoma embryonic antigen, sialyl Lewis X antigen, squamous cell carcinoma antigen and cytokeratin fragment -- are not sensitive enough to detect tumors early, according to co-investigator Dr. Ryo Nagashio of Kitasato University.
"The results of our study provide evidence that the CKAP4 protein may be a novel early sero-diagnostic marker for lung cancer," Nagashio said.
For the study, researchers examined 271 people with lung cancer, comparing them to 100 healthy people, using a monoclonal antibody, designated as KU-Lu-1 antibody, to detect lung cancer tumors.
They found the antibody reacted only with tumor cells and tumor stromal fibroblasts in lung cancer tissues, and not with normal lung tissues. There also was a validation set of samples from 100 patients with lung cancer and 38 healthy controls.
In stages I-IV, the sensitivities of serum CKAP4 was 81 percent in the first group and 69 percent in the validation set. The other biomarkers were significantly less sensitive.
They also found the sensitivity of serum CKAP4 was even high in stage I non-small-cell lung cancer and squamous cell carcinoma.
"The use of CKAP4 as a biomarker could change current practices regarding the treatment of lung cancer patients, and the diagnostic accuracies may be markedly improved by the combination of CKAP4 and conventional markers," Sato said.