Although the use of tissue-based gene expression testing for prostate cancer was found to be “highly variable in the United States at the regional level,” distinct regional trajectories of commercial adoption nevertheless exist, according to findings from a cohort study of commercially insured patients with prostate cancer published in JAMA Oncology. Specifically, results showed that “rapid” regional adoption of genomic testing “was associated with higher contextual measures of income, education, and prostate cancer services.”
In an effort to characterize national trends in testing implementation following prostate cancer diagnosis, the investigators evaluated the use of commercially available tissue-based tests from July 1, 2012 through June 30, 2018 (including claims made through December 31, 2018). The primary data source was the Blue Cross Blue Shield Axis administrative claims database, which is the largest source of commercial insurance claims in the United States.
The primary outcome was the number of claims for commercial gene expression testing 6 months after a new prostate cancer diagnosis. Testing adoption was evaluated at the hospital referral region (HRR) level using Dartmouth Atlas of Health Care criteria.
“Substantial” variation at the HRR level in the use of testing was observed, with some regions of the country showing minimal or no testing use. Regions associated with more frequent, guideline-recommended testing had a higher percentage of individuals with college education, greater median household income, higher urologist clinician density, and an elevated percentage of prostate-specific antigen testing among patients aged 68 to 74 years.
The study population included 92,418 men with prostate cancer; however, because the administrative claims used in group-based trajectory modeling did not indicate disease-stage, the study authors were not able to determine what proportion of the men had early-stage vs advanced disease.
“The region with the highest use was in North Dakota, presumably because providers in that region have taken an interest in this type of testing,” observed Michael S. Leapman, MD, principal investigator of the study. However, as a whole, the investigative team “found no clear geographic signal,” added Leapman.
Regarding utilization trends, testing was found to increase from 0.8% between July 2012 and June 2013 to 11.3% overall between July 2017 and June 2018. This rise represents a significant gain given the technology’s relatively new status, attested Leapman, who also serves as the clinical program leader of the Prostate & Urologic Cancers Program at Yale Cancer Center in New Haven, Connecticut.
Guideline-based recommendations for genomic testing in prostate cancer tend to be “somewhat ambiguous,” Leapman said, and this ambiguity “probably contributed to the wide variations in use, or underlie these variations.”