Metastases to the Kidney: An Analysis of 35 Cases and a Review of Literature

Introduction: In addition to being rare, metastases to the kidney present clinicians with issues regarding their treatment.

Materials and methods: We retrospectively analyzed 35 cases of diagnosed renal metastases. The clinical characteristics, imaging features, pathological features, diagnosis, and treatment were analyzed, and Kaplan-Meier methods and Cox regression analysis were used to calculate overall survival (OS) and influencing factors.

Results: The average age of the patients was 62 years, and 40% presented with symptoms. The most common primary tumor was lung cancer (60%), and two patients had renal metastases coexisting with renal cell carcinoma. The average interval from primary tumor to renal metastasis was 29.4 months. Only 45.5% of the patients who underwent enhanced computerized tomography were diagnosed with renal metastases. Renal biopsy was performed in 16 patients (45.7%), leading to a diagnosis in 15 (93.8%). Twenty-one patients (60%) received surgical treatment, and median recurrence free survival of these patients was 7 months (95% CI, 5 to 12). Overall, the median OS was 44 months for patients who underwent renal surgery, and 52 months for patients who did not (P = 0.672). However, for patients without metastases at other sites, surgery could significantly prolong OS (P = 0.001).

Conclusion: Although rare, the possibility of renal metastasis should be considered after finding renal tumors in patients with primary tumors in other organs, and can be diagnosed by imaging examination and puncture biopsy. For patients without other metastases, surgical intervention can be considered for the renal lesions.