Regional Differences in Stage III Nonseminoma Germ Cell Tumor Patients Across SEER Registries

We investigated regional differences in patients with stage III nonseminoma germ cell tumor (NSGCT). Specifically, we investigated differences in baseline patient, tumor characteristics and treatment characteristics, as well as cancer-specific mortality (CSM) across different regions of the United States.

Using the Surveillance, Epidemiology, and End Results (SEER) database (2004-2018), patient (age, race/ethnicity), tumor (International Germ Cell Cancer Collaborative Group [IGCCCG] prognostic groups) and treatment (systemic therapy and retroperitoneal lymph dissection [RPLND] status) characteristics were tabulated for stage III NSGCT patients, according to 12 SEER registries representing different geographic regions. Multinomial regression models and multivariable Cox regression models testing for cancer-specific mortality (CSM) were used.

In 3,174 stage III NSGCT patients, registry-specific patient counts ranged from 51 (1.5%) to 1630 (51.3%). Differences across registries existed for age (12%-31% for age 40+), race/ethnicity (5%-73% for others than non-Hispanic whites), IGCCCG prognostic groups (24%-43% vs. 14-24% vs. 3%-20%, in respectively poor vs. intermediate vs. good prognosis), systemic therapy (87%-96%) and RPLND status (12%-35%). After adjustment, clinically meaningful inter-registry differences remained for systemic therapy (84%-97%) and RPLND (11%-32%). Unadjusted 5-year CSM rates ranged from 7.1% to 23.3%. Finally in multivariable analyses addressing CSM, 2 registries exhibited more favorable outcomes than SEER registry of reference (SEER Registry 12): SEER Registry 4 (Hazard Ratio (HR): 0.36) and SEER Registry 9 (HR: 0.64; both P = .004).

We identified important regional differences in patient, tumor and treatment characteristics, as well as CSM which may be indicative of regional differences in quality of care or expertise in stage III NGSCT management.