In January 2022, Prof. Zhang Zhiling and colleagues published the original article “What happens to the preserved renal parechyma after clamped partial nephrectomy?” in European Urology, the platinum journal of Urology.

Partial nephrectomy (PN) is the reference-standard for the treatment of small renal masses primarily due to better preservation of renal function than radical nephrectomy. In most cases, PN is performed with renal artery occlusion to reduce blood loss and maintain clear visualization. However, some reports suggest that exposure to ischemia during PN may lead to residual damage to the operated kidney. In murine models, ischemia reperfusion injury (IRI) in the affected kidney can lead to fibrosis and loss of renal function. However, the histologic status of the preserved renal parenchyma years after PN in humans is unknown. What are the histologic and functional consequences of ischemia?

To compare the histologic changes of preserved renal parenchyma years after PN, we retrospectively reviewed 65 RCC patients from 19 Chinese centers and Cleveland Clinic who underwent PN and subsequent radical nephrectomy (RN) due to tumor recurrence. Histologic chronic kidney disease (CKD) scores assessing the status of the glomeruli, tubules, interstitium, and vascular structures was performed. Our objective was to assess the potential impact of ischemia versus other patient and tumor related factors.

The main findings are that deterioration of histologic status after PN was observed in the majority of patients (72%) including more substantial changes (CKD-score increase ≥3) in nearly half (45%). Most interestingly, an increased CKD-score did not correlate with type or duration of ischemia or interval from PN to RN. Rather the preexisting comorbidities of hypertension, diabetes, and/or preexisting CKD (HTN/DM/CKD) correlated with an increased rate and extent of the CKD-score. A decline of GFR was mild and similar between patients with or without substantial histologic deterioration of preserved renal parenchyma.

This is the first study to show that nearly half patients experienced histologic deterioration of residual renal parenchyma after clamped PN. Within the context of a median 23 minutes of ischemia, histologic changes in the preserved parenchyma after clamped PN appear to be primarily due medical comorbidities rather than ischemia. These results further indicated that limited ischemic duration has limited influence on renal morphology and function. This study was presented in the proceedings of the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.

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