Missing Patient Information in SEER Database May Create “Blind Spots” in Cancer Data

White MJ, Prathibha S, Luo Q, Brauer D, et al. Missing, but not Forgotten: Commission on Cancer Center Accreditation and the Impact of Missing Data in SEER Studies. J Am Coll Surg. May 2026.

Missing data is common in database research, and cancer patients with missing data are often excluded from database analyses. However, this practice may result in selection bias. In this study, White and colleagues sought to clarify the presence of selection bias in such studies, with respect to the accreditation status of the treating facility (cancer center vs non-cancer center).

Authors evaluated the prevalence of missing Surveillance, Epidemiology, and End Results (SEER) data from 2018-2020 among patients with breast, pancreas, colon, or non-small cell lung cancer (NSCLC), stratified by Commission on Cancer (CoC) accreditation status of the treating center. They also examined 3-year overall survival (OS) according to missing data status and treatment center type.

328,030 patients were identified for the study, and across disease sites, patients were predominantly treated at CoC centers (breast 82%, pancreas 83%, colon 75%, NSCLC 80%), with missing data more prevalent from non-CoC centers than CoC centers (breast 23% versus 9%, pancreas 36% versus 14%, colon 30% versus 13%, NSCLC 42% versus 13%). 

The odds of missing data were significantly higher at non-CoC centers than at CoC centers. Patients with missing data had significantly lower 3-year OS than patients with known data (breast 63% versus 81%, pancreas 5% versus 12%, colon 43% versus 61%, NSCLC 17% versus 27%, p < 0.001 for all).

For surgeons, cancer care teams, and quality improvement administrators, these data paint a clear picture: CoC accreditation is associated with significantly reduced missing data, and patients with more complete data also demonstrated greater survival. 

SEER studies that exclude patients with missing data will predominately exclude patients from non-CoC centers and may report erroneously superior outcomes by approximating registry-based, rather than population-based findings.