Natural History, Tumor Growth Kinetics, and Renal Functional Outcomes of Sporadic Bilateral Multifocal Papillary Renal Cell Carcinoma: A 25-yr Prospective Cohort Study.
Abstract
Background
AND
Objective
Bilateral or multifocal (BMF) papillary renal cell carcinoma (pRCC) arising without a confirmed pathogenic germline variant represents a clinically distinct entity with a poorly defined natural history. We aimed to establish clinical benchmarks for tumor growth kinetics, oncologic outcomes, and renal functional impact in this entity. PATIENTS AND
Methods
We identified 89 patients with histopathologically confirmed clinically sporadic BMF pRCC from a prospectively maintained, institutional review board-approved database at the National Cancer Institute (1999-2025). Tumor growth rate was calculated with a linear mixed-effects model. Active surveillance was assessed in 105 tumors from 44 patients with ≥6 mo of serial cross-sectional imaging. KEY
Findings
AND
Limitations
Over a median follow-up of 50 months, metastatic disease developed in six patients (6.7%), exclusively among patients whose largest tumor exceeded 3 cm at the time of assessment. A total of 156 renal procedures were performed, with partial nephrectomy predominating (81%). Variant pathology was identified in 18 of the 649 tumors (2.8%; 95% confidence interval 1.8%-4.3%). Among the 105 radiographically surveilled tumors, 64% demonstrated interval growth. The median tumor growth rate was 1.55 mm/yr (interquartile range 1.24-1.81). Repeat ipsilateral partial nephrectomy was associated with a significant decline in renal function (median estimated glomerular filtration rate 80.9-63.5 ml/min/1.73 m2; p = 0.002).
Conclusions
AND CLINICAL IMPLICATIONS Sporadic BMF pRCC demonstrates predominantly indolent growth and low metastatic potential, with no metastatic events observed in patients presenting with a largest tumor <3 cm. These findings provide growth-rate benchmarks consistent with active surveillance for small renal masses and nephron-sparing surgery when intervention is warranted.