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.


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“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.”

Although less than 1% of patients in each of the 5 distinct regional trajectory groups for genomic testing adoption were tested at baseline, in group 1 (lowest adoption), testing increased to 4.0% from June 2017 to July 2018. In group 5 (highest adoption), testing use increased to 33.8% of all patients tested during the same period.

The study included 3 dominant, commercially available tests for use in prostate cancer, Prolaris, OncotypeDX and Decipher, as well as ProMark, a new risk assessment tool, Leapman said. Presently, any differences between the 4 available tests in prostate cancer seem negligible as each test has clinical value, according to Lindsay Harris, MD, program director for breast cancer in the Cancer Diagnosis Program in the Division of Cancer Treatment and Diagnosis at the National Cancer Institute.

The next step will be to correlate the study’s findings with clinical outcomes. “Even though these tests are prognostic,” Leapman said, “it’s really a question of whether in human hands they lead to better medical decisions.”

This is not an easy question to answer, not only because genomic testing carries similarly high costs as magnetic resonance imaging, he said, but also because “they can be ordered by anybody” and subsequently sent to a laboratory. “These are not required tests; they’re highly discretionary,” Leapman added.

“This is an observational study, looking at trends of uptake in testing and the reasons for it,” with educational levels perhaps more important than any other influencing factor, Harris observed. “Either patients don’t understand these tests or they’re unconvinced they might be helpful to them.”

Nevertheless, as testing has become more available, so too has evidence of patient benefit, said Harris, who cited breast cancer as a field for which gene expression testing has emerged as a new standard component of treatment. “As you can see [from] this data, testing has increased in frequency of use since the technology’s development around 2013 or 2014,” Harris said.

Disclosures: Some of the study authors disclosed financial relationships with the pharmaceutical industry and/or the medical device industry. For a full list of disclosures, please refer to the original study.

Reference

Leapman MS, Wang R, Ma, S, Gross CP, Ma X. Regional adoption of commercial gene expression testingJAMA Oncol. Published online November 25, 2020. doi:10.1001/jamaoncol.2020.6086

This article originally appeared on Cancer Therapy Advisor