"While cancer is the second-leading cause of death worldwide, diagnosis at the early stages of cancer remains challenging," said Jinbo Liu, M.D., M.S., researcher at Cleveland Clinic, and lead study author. "In this study, we identified compounds that appear to be new screening biomarkers in cancer diagnosis and prognosis."

The study looked at blood samples from 55 patients with lung cancer and 40 patients with prostate cancer and compared them to blood samples of people without cancer. In a second phase of the study, blood was examined preoperatively from 24 patients scheduled for curative lung cancer surgery and again at six and 24 hours after the surgery.

The cancer patients had one- to six-times greater concentrations of serum-free fatty acids and their metabolites (the biomarker) in their blood than patients without cancer. In the second phase, the serum-free fatty acid concentrations decreased by three to 10 times within 24 hours after tumor removal surgery.

Lung cancer is the most common cancer worldwide as well as the leading cancer killer in both men and women in the United States. It causes more deaths than the next three most common cancers combined (colon, breast and prostate), according to the American Lung Association.

Prostate cancer is the most common cancer in American men, other than skin cancer, according to the American Cancer Society. While there is a blood test for prostate cancer, the prostate-specific antigen test, or PSA, has a high false-positive rate that results in many unnecessary biopsies and complications, according to Dr. Liu. The test developed in this study could be a helpful additional blood test for prostate cancer.

"This is an exciting first step to having an uncomplicated way to detect early stages of lung, prostate and perhaps other cancers," said Daniel I. Sessler, M.D., chair of the Outcomes Research Department at Cleveland Clinic. "It could also be used to measure the success of tumor resection surgery, immediately after surgery and long-term for recurrence screening."