Serum Tumor Marker Use in Patients With Advanced Solid Tumors

There is substantial variability in the frequency of serum tumor marker testing in patients with advanced solid tumors. We performed a retrospective analysis to evaluate the frequency of serum tumor marker use.

Patients with a diagnosis of advanced cancer with outpatient visits between July 1, 2013, and June 30, 2014, at a single center were included. Tumor and stage were determined by International Classification of Diseases, Ninth Revision codes and confirmed with tumor registry and medical record review. For each patient, we recorded the dates of each of the following tumor markers: a-fetoprotein, CA-125, CA 15-3, CA 19-9, CA 27-29, and carcinoembryonic antigen. We evaluated the number of tests per patient over 12 months and the maximum number of tests per patient per month.

We included 928 patients in the analysis. The mean number of any individual test per patient was seven tests, and the maximum number was 35 tests; the mean number of total tests per patient was 12 tests, and the maximum number was 70 tests; 16.3% of patients had more than 12 individual tests per year. In a 1-month span, 34.3% of patients had more than one individual test. CA 19-9 and carcinoembryonic antigen were the most commonly overused tests.

We found a high rate of serum tumor marker testing use in patients with advanced solid tumors. Given the increasing costs of cancer care, efforts should be made to determine the benefit of serum tumor markers in the follow-up care of patients with advanced solid tumors.