Kidney cancer: comparing options that preserve the kidney

A 62-year-old man, a bus driver, has an abdominal CT scan for a urinary stone and leaves with other news: a solid 3.2 cm mass in the right kidney, with contrast enhancement, no signs of spread. He has had diabetes for fifteen years, hypertension and chronic kidney disease, with an estimated filtration of 48 mL/min. The first urologist talks about removing the whole kidney. The nephrologist who follows him asks whether it is not possible to remove only the tumor. A cousin comments that he knows someone who "burned" the tumor with a needle. He arrives at the next appointment wanting to know which path protects life and which protects the kidney. The scene is fictional and was written for teaching.

This text uses the case as a scenario for clinical reasoning for students and health professionals. The topic is the organization of care in localized kidney cancer: how urology, nephrology, interventional radiology, radiotherapy and oncology compare the options taking kidney function, clinical conditions and patient preferences into account. The text does not replace your country's guideline or your service's protocol. If you play the case of the day in NEXO, you will recognize the challenge: the most eye-catching clue, the mass, is not the only one that decides the outcome.

Key points

• Many small kidney masses are low grade and have little potential to metastasize, which opens room for options that preserve the kidney.
• Kidney function before treatment is one of the factors that weigh most on chronic kidney disease after surgery.
• Biopsy of the mass has high agreement for carcinoma, but it can underestimate the grade and is sometimes not conclusive.
• Active surveillance, partial nephrectomy, ablation and stereotactic radiotherapy are real options in different profiles.
• Oncology comes in to discuss recurrence risk and adjuvant treatment after surgery in higher-risk cases.
• Shared decision-making must record what the patient values, especially when he refuses the team's recommendation.

Why the kidney calls for a team decision

Localized kidney cancer has a characteristic that changes the whole conversation: the organ that houses the tumor is also the organ the patient needs to live well in the coming decades. Removing the tumor with a safe margin solves part of the problem. Losing kidney function can create another, with more cardiovascular risk, medication adjustments and, at the extreme, dialysis. In a patient with diabetes and chronic kidney disease, like the one in the scene, the second part weighs as much as the first.

That is why the patient's question, which path protects life and which protects the kidney, cannot be answered by a single specialty. The urologist knows the anatomy of the tumor and the surgical technique. The nephrologist knows the kidney reserve, the diseases that keep damaging the kidney and what happens after losing nephrons. The interventional radiologist and the radiation oncologist offer local treatments without surgery. The oncologist assesses the risk of recurrence and the role of systemic treatment. A good decision is born when these views appear together, in the same meeting or in the same document.

This integration also protects against a known error: the first option presented tends to become the anchor of the conversation. If the patient first heard "remove the kidney", everything afterwards seems a risky alternative. The team that presents the options side by side, with the same criteria, reduces this effect.

How to set up the case meeting

A useful meeting for localized kidney cancer has a short agenda and is always the same. The radiologist presents the imaging and the complexity score. The pathologist comments on the biopsy, if there is one. The nephrologist brings the filtration, the proteinuria and the function projection for each option. The urologist says what is technically possible. The interventional radiologist and the radiation oncologist say whether the tumor is suitable for ablation or radiotherapy. The conclusion records the acceptable options, not only the preferred one, so that the conversation with the patient starts from real alternatives.

• Imaging and complexity score presented by the radiologist.
• Biopsy result, when there is one, commented on by the pathologist.
• Current and projected kidney function for each option.
• Technical feasibility of partial nephrectomy, ablation and radiotherapy.
• Acceptable options recorded, with the preferred one indicated.

The small mass and the real risk

Most kidney tumors today are found by chance, in exams ordered for other reasons. The review by Matuszczak and colleagues recalls that small, low-grade kidney carcinomas have little potential for metastasis and death from the disease, and that the main problem is choosing the right treatment for each patient, according to the review on focal therapy and active surveillance. The authors describe that surgery remains the standard, but that active surveillance and focal therapies have gained ground in selected patients.

Active surveillance is not leaving the tumor without care. In the North American DISSRM registry, described in the same review, intervention was indicated when the tumor exceeded 4 cm, grew more than 0.5 cm per year, caused symptoms such as blood in the urine, when the patient changed preference or clinical condition, or if metastases appeared, according to the review by Matuszczak. These triggers give the team and the patient a clear plan: what will be measured, when, and what changes the approach.

For the patient in the scene, surveillance is an option to discuss, but not the only one. He is 62 years old with a long life expectancy, the tumor is solid and enhances, and the decision also depends on what the biopsy and the anatomy show. The text on overdiagnosis helps to think about when treating a lesion found by chance can bring more harm than benefit.

• Size above 4 cm.
• Growth above 0.5 cm per year.
• Symptoms attributed to the tumor, such as blood in the urine with no other cause.
• Change of preference or clinical improvement that makes treatment viable.
• Appearance of disease at a distance.

Biopsy: when it helps and when it does not

Percutaneous biopsy of the kidney mass is no longer rare. In a system of 11 hospitals in the United States, 733 patients underwent biopsy between 2013 and 2023; 11 in every 100 biopsies were not diagnostic and, excluding those, agreement with the surgical specimen for kidney carcinoma was 98 in every 100, according to the study by Huang and colleagues. The same work shows the limits: all high-grade tumors on biopsy were confirmed, but 26 in every 100 low-grade tumors were reclassified to a higher grade at nephrectomy, according to the same article. Among nine oncocytic biopsies that were operated, six were carcinoma and only two were oncocytoma.

Biopsy also affects the experience of deciding. In a study with 250 patients with T1 kidney masses, 25 in every 100 underwent biopsy before the final decision, and the reduction in decisional conflict was small and not significant overall, according to the study by Gessner and colleagues. The effect was greater in patients who reported worse communication with the team, according to the same work. The lesson is that biopsy does not replace the conversation, but it can help those who left the consultation with more doubts than they came in with.

In practice, biopsy tends to change the approach when the result can lead to surveillance, ablation or radiotherapy, which require a tissue diagnosis, or when there is doubt between a kidney tumor and another disease, such as lymphoma or metastasis. When surgery is already decided and does not depend on the histological type, it adds less.

Partial or radical surgery, and the kidney that remains

Partial nephrectomy removes the tumor and preserves the rest of the kidney. Radical nephrectomy removes the entire organ. In small tumors, partial nephrectomy is preferred when technically feasible, precisely to protect function. The difference matters even more in those who already have chronic kidney disease, a single kidney or diseases that keep damaging the kidney, such as diabetes and hypertension.

A Chinese study with 649 patients who underwent radical nephrectomy at eight centers showed that 35 in every 100 had progression of chronic kidney disease stage within three years, and that filtration before surgery and tumor size were among the most important factors in the prediction model, according to the study by Wang and colleagues. The number reinforces why the nephrologist needs to see the patient before surgery, and not only after.

In patients with a solitary kidney, partial nephrectomy is almost always the path to avoid dialysis. At two referral centers, 104 patients with a solitary kidney underwent partial nephrectomy; 37 in 100 had worsening of chronic kidney disease stage, with a median follow-up of 16 months, and cold ischemia was associated with more worsening, although those cases had larger and more complex tumors, according to the study by Schmeusser and colleagues. In patients with stage 4 chronic kidney disease, a cohort with propensity score matching found no difference between partial and radical nephrectomy in progression to end-stage kidney disease or long-term dialysis, but radical nephrectomy had more pulmonary embolism, according to the study by Chang and colleagues. Both are retrospective and show that the decision depends on each patient's starting point.

What the tumor anatomy changes

Complexity scores, such as R.E.N.A.L., describe the size, the position relative to the collecting system and the depth of the tumor. Very central or endophytic tumors increase the risk of complications in partial nephrectomy and of conversion to radical nephrectomy. This is where the comparison with non-surgical options gains weight, because they also suffer from complexity, but in another way.

Ablation and stereotactic radiotherapy

Needle thermal ablation, with cryoablation, radiofrequency or microwave, is considered a standard treatment for small renal masses in selected patients. A meta-analysis of seven studies, with 113 patients and 134 complex cystic masses, found technical success in almost all cases, combined complications in about 10 in 100 and no recurrence reported during follow-up, according to the review by Meyer and colleagues. The studies were small, but the data show why the interventional radiologist needs to be in the discussion.

Stereotactic radiotherapy, once little used because kidney cancer was seen as resistant to radiation, has gained ground for patients who are not candidates for surgery. The review by Villafuerte and Swaminath describes that, in the international IROCK consortium, with 223 patients, local control was about 98 in 100 at two and at four years, according to the review published in 2024. In the same text, the FASTRACK II study treated 70 patients with tumors up to 10 cm, confirmed by biopsy and without contact with the bowel, with local control of 100 in 100 at one year, according to the review.

Tumor complexity also matters in radiotherapy. In 90 patients considered inoperable, with a median age of 77 years and mostly moderate or complex tumors, filtration fell by an average of 8.1 mL/min in the first year, 2 patients needed dialysis and freedom from local failure was 97 in 100 at three years, according to the study by Ali and colleagues. The authors conclude that the technique is an effective option for inoperable patients with complex tumors and call for studies comparing it with partial nephrectomy.

Option	For whom it is usually discussed	What weighs against it
Active surveillance	Small masses, patients with comorbidities or limited life expectancy	Anxiety, need for repeated exams, risk of growth
Partial nephrectomy	Technically resectable tumors, solitary kidney, chronic kidney disease	Surgical complications, greater in complex tumors
Radical nephrectomy	Large tumors or anatomy unfavorable for partial nephrectomy	Loss of nephrons and higher risk of chronic kidney disease
Thermal ablation	Small masses in patients at higher surgical risk	Larger tumors or tumors near sensitive structures
Stereotactic radiotherapy	Inoperable patients or tumors poorly suited to ablation	Contact with the bowel, follow-up still shorter than that of surgery

The role of nephrology before and after

The nephrologist joins the discussion with questions that change the choice. What is the real filtration, not just the estimated one? Is there proteinuria? Are diabetes and blood pressure controlled? Is the patient taking medications that will need adjustment? What is the chance of needing dialysis in the coming years with each option? These answers help weigh the benefit of preserving nephrons against the risk of each procedure.

After treatment, nephrology continues to play a central role. Filtration usually falls in the first weeks and then stabilizes. Blood pressure, blood glucose and proteinuria control, medication adjustment and guidance on contrast and anti-inflammatory drugs become part of the patient's life. In those who had a radical procedure, attention is even greater, because the remaining kidney needs to last.

• Filtration and proteinuria recorded before any procedure.
• Review of nephrotoxic medications and doses.
• Diabetes and blood pressure control as part of the oncology plan.
• Schedule of kidney function tests after treatment.
• Written guidance on contrast and anti-inflammatory drugs.

Oncology, recurrence risk and adjuvant therapy

In low-risk localized disease, clinical oncology may not even take part. But in larger, high-grade tumors or those invading nearby structures, the risk of recurrence after surgery is higher, and the discussion about adjuvant treatment changes. The Society for Immunotherapy of Cancer guideline describes that pembrolizumab was approved on November 17, 2021 for patients with clear cell carcinoma at intermediate-high or high risk of recurrence after nephrectomy, based on the KEYNOTE-564 study, according to the SITC guideline version 3.0. The same document notes that earlier attempts at adjuvant therapy with interferon, interleukin and tyrosine kinase inhibitors mostly showed no benefit over observation and had significant toxicity.

The adjuvant decision has to be truly shared, because the patient trades a future risk for present immunological effects. Oncology explains the expected benefit, the treatment duration and the effects that require attention, such as changes in the thyroid, skin, intestine and liver. Urology and nephrology continue to monitor the kidney and the operated site. Dose, regimen and eligibility criteria follow the package insert and the service protocol.

Follow-up after any option

Whatever the treatment, the patient needs to know what comes next. After surgery, follow-up combines imaging and kidney function tests at intervals that depend on risk. After ablation or radiotherapy, imaging is even more important, because the treated tumor stays in place and the team needs to tell scar from active disease. In surveillance, the tests are the strategy itself. In all cases, the final document should state who orders each test, who looks at the result and what leads to a new meeting.

For the driver in the scene, this conversation has a practical detail: he depends on being fit to drive. An option with a short recovery and less time away from work may weigh as much as the technical difference between treatments. The team that asks about work, income and support at home makes a more realistic decision and avoids patients dropping out of follow-up.

Patient preferences and refusals

The patient does not always choose what the team recommends. A case series from Qatar describes three patients with clear cell carcinoma for whom the multidisciplinary meeting recommended partial or radical nephrectomy; all three refused surgery, preferred cryoablation and had treatment failure with local recurrence that could have been avoided, according to the report by Rumaihi and colleagues. The authors discuss that shared decision-making involves patient and family, uncertainty of the evidence, the multidisciplinary meeting and the treatment team, and that professionals need training to conduct these conversations.

The lesson is not that the patient should obey. It is that the team needs to ensure the patient understood the difference between the options, record the reason for the choice and agree on follow-up. A well-documented refusal, with a surveillance plan and criteria for reassessment, is very different from a silent refusal. The text on retrospective bias and outcome bias helps remind us that a bad outcome does not prove the conversation was poorly conducted, and that a good outcome does not prove it was well conducted.

• What does the patient fear most: the disease, the surgery or dialysis?
• How much does he value avoiding hospitalization and anesthesia?
• Does he accept repeat tests and some uncertainty?
• Who decides with him at home?
• What would make him change his mind?

How NEXO helps train this reasoning

NEXO uses fictional cases with real clinical presentations, with up to six clues, to train step-by-step decisions. In kidney cancer, the skill is similar: do not let the most visible clue, the mass, erase the others, such as kidney function, associated diseases and what the patient wants. The text on how to train differential diagnosis with clues shows how to organize this reasoning, and the post on interprofessional clinical reasoning discusses how each profession contributes a part of the picture.

The Researcher track goes deeper into the mechanisms behind the clues, the Closer profile helps measure your own accuracy, Curator organizes case curation and Creators brings together those who produce medical content. The terms of use are at /economia.

Frequently asked questions

Does every kidney tumor need surgery?

No. Small masses in selected patients can be followed with active surveillance or treated with ablation or stereotactic radiotherapy. The choice depends on size, anatomy, biopsy, kidney function and clinical conditions.

Is removing only the tumor as safe as removing the kidney?

In small, technically resectable tumors, partial nephrectomy is preferred to preserve function. Oncological safety depends on adequate margins and the team's experience.

Is kidney biopsy reliable?

It has high agreement for identifying carcinoma, but some samples are inconclusive and the grade can be underestimated. Biopsy helps most when the result can change management.

Should people who already have chronic kidney disease avoid surgery?

Not necessarily. The nephrologist helps estimate the risk of worsening with each option, and the team chooses the one that balances tumor control and preservation of function.

Does radiotherapy work for kidney cancer?

Stereotactic radiotherapy has shown high local control in phase 2 studies and series of inoperable patients. Studies directly comparing it with surgery are still lacking.

Is immunotherapy always needed after surgery?

No. Adjuvant treatment is discussed in clear cell tumors with intermediate-high or high risk of recurrence, weighing benefit and immune effects.

Final checklist

• Imaging with size, complexity and relationship to the collecting system described.
• Filtration, proteinuria and associated diseases assessed by nephrology.
• Indication for biopsy discussed according to the impact on management.
• All eligible options presented side by side.
• Patient preferences and fears recorded.
• Risk of recurrence and adjuvant therapy assessed in higher-risk cases.
• Oncological and kidney follow-up plan with dates and responsible parties.

Play the case of the day on NEXO and train weighing all the clues, not just the most visible one.

References

1. Ali M, Bressel M, Chang D, et al. Impact of the R.E.N.A.L. complexity score on outcomes of stereotactic ablative body radiotherapy for primary renal cell carcinoma. BJU Int. 2025. PMID 40580074.
2. Chang NW, Chao HN, Yu CY, et al. Long-Term Outcomes of Nephron-Sparing Versus Radical Nephrectomy in Stage 4 Chronic Kidney Disease. J Clin Med. 2025. PMID 41302987.
3. Gessner KH, Deal AM, Feinberg A, et al. Impact of Renal Mass Biopsy on Decision-Making Experience for Clinical T1 Renal Masses. J Urol. 2026. PMID 41151063.
4. Huang MM, Arruza-Frau CB, Drysch AP, et al. Contemporary assessment of diagnostic performance and histologic concordance of renal mass biopsy with surgical pathology. BJUI Compass. 2025. PMID 41209078.
5. Matuszczak M, Kiljańczyk A, Salagierski M. The Role of Focal Therapy and Active Surveillance for Small Renal Mass Therapy. Biomedicines. 2022. PMID 36289844.
6. McKay RR, Ajmera A, Atkins MB, et al. Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of renal cell carcinoma, version 3.0. J Immunother Cancer. 2026. PMID 41871874.
7. Meyer HJ, Meine TC, Struck MF, et al. Efficacy and safety of percutaneous thermal ablation in Bosniak III and IV cystic renal masses: a systematic review and meta-analysis. Diagn Interv Radiol. 2025. PMID 40824176.
8. Rumaihi KA, Younes N, Khalil IA, et al. Ethical dilemmas surrounding patients´ "unwise" treatment preferences and suboptimal decision quality: case series of three renal cell carcinoma patients who developed local recurrences after non-guideline-concordant care choices. Pan Afr Med J. 2024. PMID 39867546.
9. Schmeusser BN, Yong C, Sidhom D, et al. Partial Nephrectomy in Solitary Kidneys: Intraoperative Techniques and Their Impact on Chronic Kidney Disease Progression. Cancers (Basel). 2026. PMID 42193003.
10. Villafuerte CJQ, Swaminath A. Stereotactic Body Radiotherapy for Renal Cell Carcinoma-A Review of Use in the Primary, Cytoreductive and Oligometastatic Settings. Cancers (Basel). 2024. PMID 39409955.
11. Wang X, Zhang T, Wang J, et al. Identification and validation of a chronic kidney disease prediction model after radical nephrectomy: a multicenter cohort retrospective study. Ann Med. 2026. PMID 42808223.