"Lung cancer is the leading cause of cancer-related death in both men and women worldwide," the test's inventor, Michael X. Wang, M.D., Ph.D.
, explains in the patent filing
. "Most patients with lung cancer are diagnosed at advanced stages
with an overall five-year survival rate of only 15%
A key to longer life, early cancer detection significantly raises cancer survival rates because treatment can start much sooner.
The new test accomplishes several remarkable feats, including accurate detection of Stage 1 lung cancer, says Wang, who directs the molecular pathology laboratory
at the University of Missouri School of Medicine. It also differentiates between all four stages of lung cancer
, and can determine if the cancer has spread -- metastatic vs. non-metastatic. Finally, Wang's test non-invasively monitors progress during chemotherapy.
Before now, blood tests for lung cancer have not been available. The disease is normally detected using chest X-rays, examination of cells in sputum, chest CAT scans, or a combination of the three. None of these tests detect cancer early enough, however, to "significantly improve overall mortality," Wang explains.
"There is a need to develop a reliable, noninvasive, and cost-effective confirmatory test for detection of lung cancer," he adds.
Wang's test examines microRNA (miRNA) levels in blood. Over 2,500 types of miRNA regulate normal gene expression in humans. But when certain miRNAs go bad, cancer can result.
"Human cancers commonly exhibit an altered expression profile of miRNAs with oncogenic [cancer-causing] or tumor-suppressive activity," Wang explains.
With fellow scientist Dali Zheng
, a post-doctoral research associate at Washington University in St. Louis, Wang measured three types of miRNA levels -- miR-155, 182, and 197
-- in 142 blood plasma samples from 74 lung cancer patients at various stages and 68 cancer-free patients for comparison.
On average, they found "significantly higher levels" of all three miRNA types
in the lung cancer patients, and even higher levels of just two -- miR-155 and miR-197 -- in patients with metastasis.
After chemotherapy, the blood test showed significantly reduced levels of the three miRNAs.
Wang and Dheng also discovered miR21, miR210 and miR221 are good lung cancer biomarkers, and that miR-155 levels can be used to monitor metastasis. Method for Early Detection of Lung Cancer