Kidney Tissue Slowly Shrinks for Years After Tumor-Sparing Cancer Surgery, Four-Year Study Finds

When surgeons remove a kidney tumor, they face a delicate balancing act: cut away the cancer while preserving as much of the healthy organ as possible. A new long-term study now reveals what happens to the operated kidney in the years that follow, and the picture is more dynamic than many clinicians have assumed. Researchers tracking nearly 150 patients for a median of almost four years after minimally invasive partial nephrectomy found that the remaining tissue on the operated side continues to shrink steadily, losing volume at an annualized rate of about three percent, while the opposite kidney shows little sign of stepping up to compensate.

The study, published in BMC Cancer by a team led by Zhibin Fu, Linhui Wang, and Jiazi Shi from the Naval Medical University hospitals in Shanghai, set out to answer a deceptively simple question: what is the long-term trajectory of renal parenchymal volume, the functional meat of the kidney, after tumor removal, and how does that trajectory relate to overall kidney function? To find out, the team sifted through the records of 1,947 patients who underwent laparoscopic or robot-assisted partial nephrectomy for renal tumors between January 2015 and December 2021. From that pool, 149 patients with confirmed renal cell carcinoma and complete serial imaging plus clinical follow-up made it into the final analysis.

The technical centerpiece of the work is three-dimensional CT volumetry. Rather than relying on the crude proxy of kidney length or the blunt instrument of a single blood test, the researchers measured the actual volume of functioning renal tissue on each side of the body at three time points: before surgery, at a first postoperative follow-up between one and six months, and at a last follow-up at least 36 months after the operation. Using contrast-enhanced CT images reconstructed at one-millimeter slice thickness, they employed a semi-automated segmentation workflow with an edge-snapping magnetic-lasso tool, manually corrected the contours, and verified them on coronal and sagittal reformations before letting the software calculate three-dimensional volumes. Kidney function was tracked in parallel using the estimated glomerular filtration rate, or eGFR, calculated with the CKD-EPI equation, the standard formula used to stage chronic kidney disease.

The numbers tell a clear story of slow attrition. The ipsilateral kidney, the one that was operated on, started at a median parenchymal volume of 172.57 cubic centimeters before surgery. By the first follow-up visit, a median of 2.8 months after the operation, it had already fallen to 156.66 cubic centimeters, reflecting the immediate loss of tissue removed with the tumor along with early postoperative changes. But the shrinkage did not stop there. At the last follow-up, the volume had dropped further to 136.04 cubic centimeters, which works out to an annualized decline of 3.00 percent during the late follow-up period. In other words, the operated kidney kept losing functional tissue year after year, long after the surgical wound had healed.

Perhaps the most striking finding concerns the contralateral kidney, the untouched organ on the other side of the body. Conventional wisdom holds that when one kidney loses capacity, the other hypertrophies to pick up the slack, a phenomenon well documented after living kidney donation and radical nephrectomy. Yet in this cohort, the healthy kidney barely changed: 175.02 cubic centimeters before surgery, 179.92 cubic centimeters at the first follow-up, and 178.80 cubic centimeters at the last. The researchers found no significant evidence of compensatory hypertrophy. Total parenchymal volume across both kidneys declined at an annualized rate of 1.08 percent, and eGFR declined at 0.65 percent per year, with wide interquartile ranges indicating that some patients fared considerably worse than others.

To understand why some kidneys atrophy faster than others, the team ran univariate and multivariate linear regression models covering demographics, comorbidities, tumor characteristics, and surgical parameters. Three factors emerged as independently associated with the annualized rate of ipsilateral volume loss. Tumor composition mattered: patients with cystic tumors, which are fluid-filled and often require less parenchymal resection, showed different atrophy rates than those with solid tumors, with a p-value of 0.028. Surgical method also played a role, with robot-assisted procedures differing from laparoscopic ones at p equal to 0.048, a result that will feed the ongoing debate over whether the robot’s enhanced dexterity and finer suturing translate into better long-term organ preservation. Finally, ischemia type was associated with volume loss at p equal to 0.023, comparing patients whose renal blood flow was not temporarily clamped with those who underwent warm ischemia, the period during which the kidney is deliberately starved of blood while the surgeon reconstructs it.

Intriguingly, no independent predictors were identified for the annualized change rates of the contralateral kidney, total parenchymal volume, or eGFR. The healthy kidney’s behavior and the overall functional decline appear to follow their own course, resistant to the clinical variables the team tested. When the researchers instead looked at the absolute values at the last follow-up, a different set of relationships surfaced. Final total parenchymal volume was independently associated with patient age and preoperative volume measurements, while final eGFR was independently predicted by age, preoperative contralateral volume, and preoperative eGFR. The practical implication is sobering but useful: the best predictor of how a patient’s kidneys will function years after surgery is largely written into the patient before the first incision is made.

The disconnect between volume and function deserves attention. A three percent annual loss of ipsilateral tissue did not translate into a proportionally steep eGFR decline, likely because the global filtration rate blends contributions from both kidneys and because the relationship between parenchymal mass and filtration capacity is nonlinear. This is precisely where the authors argue CT volumetry earns its place. By measuring each kidney separately, volumetry offers a window into split renal function that serum creatinine and eGFR cannot provide. A stable eGFR can mask progressive atrophy on the operated side that only becomes clinically meaningful if the other kidney later falters, a scenario relevant to patients at risk of chronic kidney disease from diabetes, hypertension, or future contralateral tumors.

The study’s design carries caveats worth noting. It was a retrospective cohort approved by the Institutional Review Board of Changzheng Hospital and conducted under the Declaration of Helsinki, drawing on patients who happened to have complete serial imaging, which may introduce selection bias toward healthier or more closely monitored individuals. The ischemia finding, the authors note, is exploratory after adjustment. The median follow-up of 47.4 months, with an interquartile range of 36.0 to 60.4 months, is long by surgical oncology standards but still may not capture atrophy trajectories over decades. Funding came from the National Natural Science Foundation of China and the Changfeng Talent Development Program, and the authors declared no competing interests.

Even with those limitations, the message for patients and clinicians is actionable. Partial nephrectomy remains the standard of care for localized renal cell carcinoma precisely because it spares tissue and protects long-term kidney function compared with radical removal of the whole organ. This study does not challenge that standard; it refines the follow-up playbook. The operated kidney is not a finished structure once the tumor is out. It is a slowly remodeling organ whose parenchyma continues to atrophy at a measurable, predictable clip, and the opposite kidney, contrary to textbook expectations, does not reliably enlarge to compensate. The authors recommend integrating CT-based volumetric assessment into long-term postoperative surveillance, so that creeping volume loss can be detected and weighed against blood-based function measures before it becomes a clinical problem. For the growing population of kidney cancer survivors living decades after surgery, that shift from snapshot monitoring to longitudinal volumetric tracking could prove one of the quieter but more consequential legacies of this research.

Subject of Research: Long-term changes in renal parenchymal volume and kidney function after minimally invasive partial nephrectomy for renal cell carcinoma

Article Title: Changes in renal parenchymal volume and renal function after minimally invasive partial nephrectomy for renal cell carcinoma at median 47.4-month follow-up

Article References: Fu, Z., Wen, Q., Wu, C., Chen, F., Ni, J., Wang, J., Wang, J., Zhang, Z., Chen, M., Wu, Z., Wang, L., & Shi, J. (2026). Changes in renal parenchymal volume and renal function after minimally invasive partial nephrectomy for renal cell carcinoma at median 47.4-month follow-up. BMC Cancer. https://doi.org/10.1186/s12885-026-16996-y

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16996-y

Keywords: renal cell carcinoma, partial nephrectomy, renal parenchymal volume, eGFR, CT volumetry, kidney function, warm ischemia, robot-assisted surgery, laparoscopy, chronic kidney disease, surgical oncology, nephrology