Renal neuroendocrine neoplasms: a single-center experience

Abstract Background Primary neuroendocrine neoplasms (NENs) of the kidney are exceedingly rare malignancies and the available literature is very limited. The natural history and response to treatments is not well characterized. Objective We aimed to describe the presenting features, demographics, tumor characteristics, and treatment outcomes of patients with renal NENs. Methods We performed a retrospective analysis of all Mayo Clinic patients with a tissue diagnosis of a primary renal neuroendocrine neoplasm. Baseline patient and surgical pathologic features were collected, as well as treatment modalities. Time to recurrence after resection and overall survival were estimated with survival analysis. SEER data was used to estimate population-wide incidence and overall survival. Results Seventeen patients were included with a median follow-up of 62.8 months. Distant metastasis was present in 29 percent at diagnosis, with 76 percent experiencing distant metastasis at any point. Twenty-four percent had horseshoe kidney. Fourteen of 17 patients had surgical resection with no evidence of disease after surgery. Ten of these patients had documented recurrence. The median time to recurrence was (TTR) 18 months (95% CI 9 - 46). Only one patient out of ten had a radiographic response to systemic therapy. Four out of 9 patients had stable disease with somatostatin analogs (SSA). The median overall survival (OS) was 143 months (95% CI 50 - 143). Conclusion Renal NENs are rare malignancies affecting mostly middle-aged patients, with distant metastasis being common. About half of patients experience stable disease with SSAs. The OS is usually greater than 5 years.