Image: A scanning electron micrograph (SEM) of prostate cancer cells (Photo courtesy of David McCarthy).
Measuring serum levels of tumor markers may serve as an early indicator of the progression of established tumors in the face of ongoing treatment.
Tumors frequently secrete complex molecules into the blood that are traditionally associated with a single dominant cancer type, for example prostate specific antigen (PSA) linked to prostate cancer, carcinoembryonic antigen (CEA) to colorectal cancer, CA125 to ovarian cancer, CA19.9 to pancreatic cancer, and CA27.29 to breast cancer. While levels of these markers are readily measured by immunoassays, these measurements have not proven useful for screening otherwise healthy people for evidence of underlying cancers.
Investigators at the University of Colorado School of Medicine (Denver, USA) examined the possibility of using tumor marker measurements as a means to manage therapy of advanced non-small cell lung cancer (NSCLC). Towards this end, they conducted a single center retrospective analysis of available CEA, CA125, CA19.9 and CA27.29 levels at baseline and on treatment in stage IV lung adenocarcinoma. Tumors where classified according to individual oncogene drivers. NSCLC tumors from 142 patients were analyzed. The tumors were linked to the following oncogenes: ALK=60, EGFR=50, ROS1=4, and KRAS=28.
Results revealed that during disease progression, a 10% or greater rise in the concentration of blood tumor markers occurred in 53% of patients. However, if the progression was limited to the brain, the tumor markers increased in only 22% of cases. Among the patients, 82% had at least one marker; 95% if all four markers were measured (CA27.29 highest frequency of elevation, CA19.9 lowest). Increases in tumor marker concentration during therapy could occur well in advance of radiographic changes of progression (by up to 84 days).
"If you ask some oncologists, they might say that there is no point checking these markers in lung cancer, as it does not express them," said senior author Dr. D. Ross Camidge, professor of thoracic oncology at the University of Colorado School of Medicine. "Clearly, these markers are not a substitute for routine surveillance scans looking for progression, especially in the brain. However, this is where the art of medicine may have to be appreciated. If the markers are going up but a CT scan says everything is still fine, maybe these data should nudge you to do a more detailed scan - like a PET/CT scan. Or if the best body scans are all stable, perhaps a rise in tumor markers should nudge you to do a brain scan looking harder for a hidden site of progression."
The study was published in the August 24, 2017, online edition of the Journal of Thoracic Oncology.
University of Colorado School of Medicine