Factors Associated With Rare Pediatric Cancer Trial Enrollment: A Report From the Children's Oncology Group Rare...

Over 90% of US children with cancer are treated at Children's Oncology Group (COG) centers, which seek to maximize enrollment in therapeutic and biobanking studies. Rare cancers have demonstrated lower than expected COG enrollment. We evaluated trends in COG rare cancer enrollment compared to US incidence from Surveillance, Epidemiology, and End Results (SEER) registries, examining the impact of COG therapeutic trials and Project:EveryChild, a cancer biobank/registry.

COG and SEER data from 2002 to 2020 were queried for US patients younger than 18 years old with adrenocortical carcinoma (ACC), nasopharyngeal carcinoma (NPC), retinoblastoma (RB), thyroid carcinoma, and melanoma. We compared demographic data between COG and SEER, extrapolating incidence for each cancer to analyze trends in COG enrollment.

Patient characteristics, including age, sex, and race, were similar between COG (n = 2184) and SEER (n = 5514). COG enrollment for rare cancers remained low (11%). Initiating Project:EveryChild did not increase enrollment (12% pre- vs. 8% post-Project:EveryChild; p < 0.01). For cancers with available therapeutic trials (ACC, NPC, and RB), COG enrollment was higher during trial accrual (40%) than when no trial was open (12%; p < 0.01). Patient geography and income did not appear as barriers to COG enrollment.

Although children with rare cancers enrolled in COG studies reflect the US population, enrollment in the COG registry/biospecimen repository continues to be limited in the absence of therapeutic trials, impacting data and biospecimens available to inform therapeutic trial development. Expansion of therapeutic trials or free molecular testing through the Molecular Characterization Initiative may increase data and biospecimens for these rare cancers.