ALK testing rates increasing in NSCLC patients
By Anne Harding
NEW YORK (Reuters Health) - Testing for mutations in the ALK gene in patients with non-small-cell lung cancer (NSCLC) who are candidates for targeted therapy nearly doubled from 2011 to 2016, according to a new study in U.S. community practices.
"That's very, very encouraging," Dr. Peter B. Illei of Johns Hopkins Medical Institutions in Baltimore, Maryland, who led the study, told Reuters Health by phone.
But other aspects of the findings raised concerns, he added, including that in 2016, 25% of patients with non-squamous histology did not receive ALK testing, and that patients covered by Medicaid were less likely to be tested than those with commercial insurance.
From 2% to 8% of patients with NSCLC have translocation of the ALK gene, Dr. Illei and his team note in JCO: Precision Oncology, online October 3. The Food and Drug Administration approved the first ALK inhibitor, crizotinib, in 2011, and other first- and second-generation ALK inhibitors have followed.
Guidelines recommend that patients with adenocarcinoma histology, and those for whom adenocarcinoma cannot be ruled out, be tested for ALK, as well as younger NSCLC patients, those with mixed histology, and those without a history of smoking. "These guidelines are out there, and if we follow them patients will benefit," Dr. Illei said.
But several obstacles can exist to molecular testing of malignancies, he noted, for example biopsies that are too small for analysis.
To investigate "real world" ALK testing rates, Dr. Illei and his colleagues looked at more than 31,000 patients diagnosed with stage IIIB or IV NSCLC at community practices between 2011 and 2017.
Overall, 53.1% of patients had ALK testing, with the rate rising from 32.4% in 2011 to 62.1% in 2016. There were 633 patients with ALK translocation, or 3.8% of those tested overall. ALK-positive rates were 4% in patients with nonsquamous histology, 1.6% in those with squamous histology and 3.6% in patients with not otherwise specified histology.
Among patients with nonsquamous histology, two-thirds were tested for ALK, with the rate rising from 41.1% to 75.1% between 2011 and 2016. Among patients with squamous histology, 18.5% were tested, and rates rose from 12.1% to 26.5% over the study period.
Women were more likely to receive ALK testing, while older patients, those with a smoking history, those not living in the West and those with recurrent disease were less likely to receive it.
Patients with Medicaid coverage had 40% lower odds of receiving ALK testing than did those with commercial insurance, while those on Medicare had 7% lower odds - both significant reductions.
"We wanted to focus on the community because 70% of lung cancers are treated in the community, and treated by people who are not necessarily specialists in lung cancer," Dr. Illei said. "Because the new drugs are even better than the old ones, it's even more important to treat these patients and treat them appropriately and without delay."
He and his colleagues conclude: "Improvement in ALK testing frequency and timeliness of ALK testing results, including optimization of sample processing for laboratory submission, has important clinical implications for patients with ALK rearrangements."
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