Clinicopathologic Features and Survival Outcomes for Primary Renal Neuroendocrine Neoplasms

Primary renal neuroendocrine neoplasms (NENs) are exceedingly rare. We used the Surveillance, Epidemiology, and End Results (SEER) data to summarize clinicopathologic characteristics, treatment outcomes, and prognostic factors of primary renal NENs.

Data were identified from the SEER database. Clinicopathologic characteristics were compared by the Pearson chi-square or correction test, in which continuous variables were analyzed by t test. Kaplan-Meier analyses and log-rank tests were used to compare the differences in overall survival (OS). Univariable and multivariable regression model analyses of OS were conducted using the Cox proportional hazard model. Also, we used directed acyclic graphs to guide the multivariable regression model and to try to determine the impact of each of surgery, chemotherapy, and radiotherapy on OS.

A total of 132 patients were enrolled. There were significant differences in age, grade, tumor size, SEER stage, surgery, and chemotherapy between patients with carcinoid tumors and those with neuroendocrine carcinomas. Patients with disease with carcinoid tumors, younger age, smaller tumor size, and lower SEER exhibited better survival outcomes. Univariable and multivariable regression models analyses indicated that age, sex, tumor size, and SEER stage were independent prognostic factors for OS. Directed acyclic graphs guided the respective inclusion of variables in the multivariable regression model to assess the causal effect of surgery, chemotherapy, and radiotherapy on OS. The results showed that surgery, chemotherapy, and radiotherapy did not improve OS.

Primary renal NENs are exceedingly rare and exhibit different biological behavior. Older age, male sex, larger tumor size, and tumors not confined to the renal parenchyma may indicate poor prognosis. Resection of all visible disease remains the reference-standard treatment of choice. Longer-term studies with a larger patient cohort are needed to determine systemic therapeutic options.