medwireNews: Researchers have warned that underuse of mismatch repair (MMR) deficiency testing “is a persistent and pervasive problem” in the USA, even among young adults with colorectal cancer (CRC) where its use is unequivocally recommended.
Their study of more than 150,000 adults with CRC showed that a little over a quarter underwent MMR deficiency testing between 2010 and 2012, with this figure rising to just under half of young adults with CRC despite long-standing national guidelines recommending routine testing in this younger group.
Although the proportion of patients tested increased during the study period, the researchers identified several characteristics relating to patients, their disease and facility that were independently associated with underuse of MMR deficiency testing.
“Of particular concern, our study noted significant independent associations between patient socioeconomic and insurance status as well as cancer program location and type and utilization of MMR deficiency testing, suggesting that patient and health care system-level interventions tailored to groups at risk for nonadherence are warranted to ensure optimal and uniform implementation of newly endorsed, universal testing guidelines,” they report.
The US team led by Nestor Esnaola (Fox Chase Cancer Center, Philadelphia, Pennsylvania) studied 152,993 adults on the National Cancer Database diagnosed with CRC between 2010 and 2012.
They found that overall just 28.2% underwent MMR deficiency testing, although the proportion tested increased significantly from 2010 to 2012 (22.3 vs 33.1%).
Among 17,218 younger adult patients, aged 18 to 49 years, just 43.1% underwent MMR deficiency testing, with the proportion tested again significantly increasing between 2010 and 2012 (36.1% vs 48.0%).
Factors independently associated with MMR deficiency testing, irrespective of age, included higher educational level (odds ratio [OR]=1.38), later diagnosis year (OR=1.81), early-stage disease (OR=1.24), and having at least 12 regional lymph nodes examined (OR=1.44).
Those associated with the underuse of MMR deficiency testing included older age (OR=0.31), Medicare coverage (OR=0.89), Medicaid coverage (OR=0.83), or lack of insurance (OR=0.78).
In addition, use of a nonacademic versus an academic or research facility type, a rectosigmoid or rectal tumor location, unknown tumor grade, and nonreceipt of definitive surgery were also associated with underuse of MMR deficiency testing (OR=0.44, 0.76, 0.61, and 0.33, respectively).
Reporting in JAMA Oncology, the researchers maintain: “Our study provides important, national baseline data regarding utilization of MMR deficiency testing in patients with CRC and identifies significant groups at risk for potential nonadherence to newly implemented universal testing guidelines moving forward.”
By Anita Chakraverty
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