Neuroendocrine tumors of the kidney: A single institution experience

Renal neuroendocrine tumors (NETs) consisting of well-differentiated carcinoid tumors and poorly-differentiated small cell carcinomas are a rare group of neoplasms with limited information on treatment course and outcome. In our retrospective study we present a case series of these tumors and highlight the importance of upfront systemic chemotherapy over immediate nephrectomy in small cell carcinoma of the kidney. Background: Renal NETs, comprised of carcinoid tumors and small cell carcinomas, are a rare group of neoplasms. The rarity of these tumors pose a diagnostic and therapeutic challenge. Our purpose was to characterize the cases treated at a tertiary cancer center and to evaluate patient outcomes with the available treatment modalities. Patients and Methods: This was a retrospective study of patients with renal NETs seen at The University of Texas M.D. Anderson Cancer Center between January 1, 2001, and January 1, 2011. Patient and tumor data were analyzed using descriptive statistical methods. Results: Three cases of carcinoid tumors and 6 cases of small cell carcinoma were identified. The median age at diagnosis was 53 years for patients with carcinoid and 65 years for patients with small cell carcinoma. The most common presenting symptoms were back pain, flank pain, and hematuria. The morphological appearance of the tumor cells and their immunohistochemical reactivity for neuroendocrine markers and cytokeratin helped establish the diagnosis. Nephrectomy was the mainstay of treatment for carcinoid tumors, yielding good long-term results, even in the presence of metastases. Surgery and chemotherapy were used for small cell carcinoma of the kidney. The median overall survival for patients with small cell carcinoma of the kidney was 17.3 months. Conclusion: Renal carcinoid tumors are indolent and are associated with prolonged survival, and small cell carcinomas of the kidney are aggressive tumors with relatively short overall survival. Although palliative in nature, cytotoxic chemotherapy is the mainstay of therapy and is best given before surgery.