Regional differences in penile cancer patient characteristics and treatment rates across the United States

Introduction: We tested for regional-specific differences in patient, tumor and treatment characteristics as well as cancer-specific mortality (CSM) of squamous cell carcinoma of the penis (SCCP) patients, across the Surveillance, Epidemiology, and End Results (SEER) registries.Methods: The SEER database (2000-2018) was used to tabulate patient (age at diagnosis, race/ethnicity), tumor (stage, grade, N-stage) and treatment characteristics (proportions of primary tumor surgery, local lymph node surgery, systemic therapy), according to 12 SEER registries. Multinomial regression models, as well as multi -variable Cox regression models tested for CSM differences, adjusting for patient, tumor and treatment characteristics.Results: In 5395 SCCP patients, registry-specific patient counts ranged from 2060 (38 %) to 64 (1 %). Differences across registries existed for race/ethnicity, stage, grade and N-stage. Additionally, in stage I-II SCCP patients, proportions of local tumor destruction (LTD) ranged from 19 % to 39 % and from 33 % to 61 % for partial penectomy. In stage III-IV SCCP patients, proportions of partial penectomy ranged from 40 % to 59 % and from 17 % to 50 % for radical penectomy. Local lymph node surgery ranged from 8 % to 24 % and proportions of systemic therapy ranged from 3 % to 14 %. Significant inter-registry differences remained, after adjustment for treatment proportions. Unadjusted five-year CSM ranged from 19 % to 32 %. In multivariable analyses, one registry exhibited significantly higher CSM (SEER registry 10, Hazard Ratio [HR] 1.48), relative to the largest reference registry (SEER registry 1, n = 2060).Conclusion: Important regional differences including patient, tumor and treatment characteristics exist for SCCP patients across SEER registries. After multivariable adjustment, no differences in CSM were recorded, with the exception of one registry.