Serum Protein Panel Detects Lung Cancer


DURHAM, N.C., Dec. 7 -- A blood test based on four serum proteins could screen for lung cancer, researchers here said.
Action Points --->
Explain that the study identified four proteins in blood that are strongly correlated with lung cancer.
Explain that the results need to be confirmed in larger, prospective studies before they can be used clinically.
The markers distinguished lung cancer patients from control patients with 77.8% sensitivity and 75.4% specificity, reported Edward F. Patz, Jr., M.D., and colleagues at Duke University, in the Dec. 10 issue of the Journal of Clinical Oncology.
"Remarkably, 90% of patients who fell into any one of three groupings [of the markers] had lung cancer," they said.
The four proteins were carcinoembryonic antigen (CEA), retinol binding protein (RBP), alpha-1-antitrypsin (AAT), and squamous cell carcinoma antigen (SCCA).
In the short term, the panel could be used to determine if patients with suspicious lung lesions in radiographs should have follow-up biopsies, the researchers said.
Assuming the panel's sensitivity and specificity is confirmed in larger studies, it might also be used to screen patients for lung cancer risk, they noted.
The researchers identified RBP and AAT as potentially diagnostic for lung cancer in proteomic studies they conducted on serum samples from 28 lung cancer patients and 28 controls. They added CEA and SCCA to the panel based on earlier studies linking them to lung cancer.
A classification and regression tree model determined what levels of these markers, in various combinations, could best distinguish lung cancer patients from age- and sex-matched controls, based on samples from 50 patients and 50 controls.
Seven different combinations were identified that distinguished patients from controls.
For example, all 15 samples with CEA levels greater than 2.14 ng/mL and RBP levels not greater than 102.9 μg/mL were from lung cancer patients.
The seven schemes were then applied to blinded serum samples obtained from a different group of 49 lung cancer patients and 48 patients who did not have lung cancer.
The researchers found that three of the schemes best identified those with lung cancer:
1.01 <> 0.77 ng/mL; AAT > 2.04 mg/mL
CEA > 2.14 ng/mL; RBP ≤ 102.9 μg /mL
CEA > 3.47 ng/mL; RBP > 102.9 μg /mL
Fifty-seven percent of all lung cancer cases were assigned to one of these schemes, while only 6% of control cases were in these groups. "If a patient was assigned to one of these [groups], they had a 90% probability of having lung cancer," the researchers said.
"The most immediate scenario in which this panel could be used is when an indeterminate pulmonary nodule is detected on imaging studies, whether detected in a screening trial or performed for other indications," the researchers said. Patients with low risk according to the blood test could be monitored with periodic imaging studies and blood tests, while a high-risk test result would call for immediate intervention.
Dr. Patz said the group was planning a larger, prospective study of the panel in patients with lung lesions on CT scans.
He said the ultimate goal is to use the panel for screening purposes. Those showing a high likelihood of cancer based on the test would have CT scans for further evaluation.
No financial disclosures were reported.
Primary source: Journal of Clinical OncologySource reference:Patz E, et al "A panel of serum biomarkers for the diagnosis of lung cancer" J Clin Oncol 2007; 25: 5578-83.