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BackTable / Urology / Article
Risk Stratification in Small Renal Masses: Who Needs Treatment?
Evangeline Adjei-Danquah • Updated Oct 31, 2025 • 32 hits
The incidental discovery of small renal masses has become more common with the widespread use of advanced imaging techniques.Not every lesion carries the same biological behavior or clinical risk, and the rise in detection has not been matched by a decline in kidney cancer mortality. These trends highlight some concerns among experts over potential overdiagnosis and overtreatment. Risk stratification has emerged as an essential framework for guiding management decisions by helping clinicians distinguish which patients truly need intervention from those who can be safely monitored over time.
This approach integrates multiple dimensions beyond size alone, incorporating tumor growth kinetics, imaging characteristics, patient age, comorbidities, and genetic predispositions. It also reflects a shift toward personalized medicine, where biopsy findings and emerging biomarkers increasingly inform individualized care. By thoughtfully balancing these variables, clinicians can reduce unnecessary surgeries, protect renal function, and address patient anxiety with data-driven reassurance. Ultimately, the goal of this approach is to direct treatment toward the minority of small renal masses that pose acute and significant risk while promoting a measured, patient-centered approach to care
This article features excerpts from the BackTable ENT Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable Urology Brief
• Incidental small renal masses are increasingly detected, yet many are benign or indolent, making risk stratification essential to avoid unnecessary interventions
• Patient age, comorbidities, and hereditary cancer syndromes are key factors that shape whether tumors should be treated urgently or can be safely monitored
• Overtreatment remains a challenge, and the integration of biopsy and emerging biomarkers can help refine risk stratification and reduce unnecessary surgeries
Table of Contents
(1) Balancing Overdiagnosis & Patient Anxiety
(2) Age, Comorbidities & Genetic Syndromes in Clinical Decision-Making
(3) The Big Picture in Risk Stratification
Balancing Overdiagnosis & Patient Anxiety
Largely due to increases in access to imaging equipment, more patients are being diagnosed with incidental small renal masses, many of which are indolent or benign. This surge in detection has not translated to a corresponding drop in kidney cancer mortality, suggesting a growing issue of overdiagnosis. Risk stratification helps physicians separate those who truly need intervention from those who can be safely monitored over time. During the initial consultation, clinicians often emphasize perspective – explaining that not all kidney tumors are aggressive, and that immediate surgery is not always warranted. They share data showing that many small masses are benign or biologically indolent, and that time can often be the best diagnostic tool.
In some cases physicians can also highlight how aggressive intervention can sometimes do more harm than good, exposing patients to surgical risks or nephron loss for a tumor that might never have progressed. By carefully reviewing imaging, offering biopsy when appropriate, and discussing growth kinetics, they help patients understand their specific risk profile.
[Dr. Aditya Bagrodia]
Fantastic. We're trying to figure out what comes next here. Cancer, no cancer, if cancer, dangerous cancer, histology of cancer. Do you use nomograms? Are you using Sestamibi scans? What kind of information are you trying to glean here that you think is robust enough to help your decision-making?
[Dr. Christopher Anderson]
There have been multiple different questions asked about how can we better figure out what this tumor is based on our CAT scan alone. Does an MRI help? Maybe a little bit. Are there nomograms that can help? Probably not. The nomograms actually don't appear to be that effective, and there's a review that looked at several of them that said that they just weren't very good. There's some PET tracers that have been studied. I think there's a lot of interest in them, including Sestamibi. There's been a couple of studies that look at Sestamibi. That's a tracer that looks at mitochondria-rich structures, which oncocytomas are.
The thought is, well, if you have a Sestamibi PET-positive renal mass, then it's probably an oncocytoma, and maybe you can avoid any aggressive treatment. I think the jury's still out on whether or not that's the best way to identify or rule out the presence of an oncocytoma. There's ongoing studies on CA9, which is another PET tracer that looks for clear cell carcinoma. I think we have to learn whether that's going to be helpful, but a lot of interest in that at least.
Then surgery, taking it out and doing an excisional biopsy, which is what we've historically and continue to do, where we'll say, "Hey, listen, I don't know what this is. There's probably cancer. Let's take it out and let's see what it is. We'll do a partial nephrectomy, a robotic partial nephrectomy, or even a radical nephrectomy if needed, and then I'll tell you in a week whether or not we were right."
That's a very effective treatment for cancer, very high cure rate for small organ-confined kidney cancers. The collateral damage here is that you're taking out like 5,000 benign tumors a year, which exposes patients to cost of treatment, to risk of treatment. You wonder, is it possible to avoid surgery for benign tumors or vice versa? Is it necessary to remove benign tumors from the kidney?
Similarly, we are removing tens of thousands of what are considered indolent tumors from the kidney. Should we be doing this? Are these tumors that need to be removed? This brings up the concern of over-treatment now. We've had these discussions with prostate cancer, not only over-detection but over-treatment. Are we seeing the same thing for kidney cancer, where we're not only over-detecting it, but are we over-treating it with all of these surgeries? Possibly.
[Dr. Aditya Bagrodia]
You took the prostate cancer analogy right out of my head; low volume, grade group 2 disease, small pattern 4, a lot of interest in focal therapy which I think is coming. It's coming. It's here, but I certainly think you could make a case for whether that should be treated. There's no free rides, right? Somebody is going to have an issue, problem, or complication.
I have a significant interest in testicular cancer, and I feel like, for instance, robotic RPLND is such a generally different operation than open RPLND. Robotic partial nephrectomy, which has now been around for decades, literally is such a different operation than open partial nephrectomy that people may feel that, "Oh, I can just do this, hospital, one day, no heavy lifting for three weeks, and get on with it, and it's done." Whether that ultimately is in the patient's best interest is tough.
[Dr. Christopher Anderson]
Absolutely. That's been shown, too, by the way. The diffusion of robotic surgery has led to increase in use of nephrectomy, specifically partial nephrectomy, so we're seeing that. The more CAT scans you do, the more nephrectomies you do. The more robotic surgery that's being done, the more nephrectomies that are being done. Whether or not this is actually helping patients with their kidney cancers is yet to be determined, frankly.
[Dr. Aditya Bagrodia]
I think just to complete that thought I had from earlier, I mentioned that like half a century ago, you would have gotten a radical, quarter of a century ago, a partial, over the last 20 years, ablation, now observation. This is what I tell patients. We can either monitor it without a biopsy, we can burn it or freeze it, or we can cut it out. We can generally do that robotically. Where are you thinking about an upfront biopsy?
[Dr. Christopher Anderson]
This is a great question, and I'm glad that we're able to talk about this. There's a lot, I think, that I don't know, that we collectively don't know, that we still need to learn about. I think that it does provide value, and I think there's a lot of patients who benefit, frankly, from having a biopsy. Historically, biopsies were not used. Doctors didn't want to use them. They didn't trust them. There's problems with biopsy performance, et cetera.
We're seeing an uptick now in the use of biopsies, so there's gaining momentum here. I do talk to patients about it. I talk to them about it because of a lot of what we've already discussed, which is, "Listen, it's unclear if what you have is something that's dangerous to you. Maybe I can do a test to give you more information to help you understand whether this is a tumor that could be a threat to your life and whether this can help inform what type of treatment to recommend in your case.
[Dr. Aditya Bagrodia]
Fantastic. Some of them, little tip shots, history of other cancers that are legit.
[Dr. Christopher Anderson]
Easy. Rule out metastasis. Rule out infection, inflammatory conditions. In hematologic people, you might have history of lymphoma. That's all. In the AUA guidelines, that's when we should, without question, be considering renal biopsies. Solitary kidneys, stakes are high.
[Dr. Aditya Bagrodia]
You don't want to get in there. Good news is it's benign. Bad news is you're on dialysis.
[Dr. Christopher Anderson]
You're on dialysis.
[Dr. Aditya Bagrodia]
That's never good. Same for bilaterals. Do you like biopsies and bilaterals, Chris?
[Dr. Christopher Anderson]
Yes, I do. Actually, I think they can be very valuable. Sometimes if you're thinking about maybe some sort of a syndromic picture, then that might point you down a certain pathway. Absolutely.
[Dr. Aditya Bagrodia]
If you're considering an ablation, biopsy before or at the time of?
[Dr. Christopher Anderson]
That's controversial. There's different practice patterns there. I will say that there are several series now, institutional series that have suggested that biopsy before, whether you do ablation or surgery or anything else, it does change treatment decision-making. There's large studies from Canada, UC Irvine, Atrium Health in Carolina, that have found that if you do biopsies more regularly, you're less likely to surgically remove benign tumors. You're more likely to use active surveillance.
There's some data that suggests that perhaps some types of ablation work better for non-clear cell compared to clear cell, so maybe that could help inform your decision-making in those cases. At the very least, at the time of ablation, sometimes that's not even done in itself. At the very least, you want to do a biopsy at the time of ablation, but optimally even beforehand.
[Dr. Aditya Bagrodia]
Makes sense. Then broad strokes, I think the AUA guidelines indicate that you shouldn't do a biopsy if it's not going to change your decision-making. If they're 100 years old, a couple of heart attacks and a stroke, renal mass, you're not going to do anything. Don't biopsy them.
[Dr. Christopher Anderson]
Absolutely. That's easy. You're not going to touch a patient, you're not going to ablate them no matter what. Don't stick any needles in them. It's not going to affect your decision-making.
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Age, Comorbidities & Genetic Syndromes in Clinical Decision-Making
Risk stratification extends beyond tumor size to include patient age, overall health, and genetic background. These factors collectively guide how physicians balance intervention with observation, tailoring decisions to each individual’s medical context and life expectancy. Comorbidities often play a significant role – patients with significant health burdens may benefit more from surveillance than from invasive treatment, whereas those with fewer risks might tolerate or require intervention sooner.
Genetic predispositions also add critical layers of complexity. Hereditary cancer syndromes such as von Hippel–Lindau (VHL), hereditary leiomyomatosis and renal cell carcinoma (HLRCC) carry a greater risk of aggressive tumor biology and necessitate closer monitoring and earlier management. Understanding these nuances allows clinicians to refine treatment recommendations, ensuring that decisions align not only with the disease process but with the patient’s overall health goals and long-term well-being
[Dr. Aditya Bagrodia]
This has been super informative, and I guess it brings us to some of the global 10,000-foot view questions here. Maybe I'll just ask you, Chris, what are those questions in your mind as you're considering, "Do I operate or not?" or "Do I treat or not treat? Do I do a biopsy?" What are some of the things that are running through your mind?
[Dr. Christopher Anderson]
I think patient goals are very important. We take a lot of time talking to our patients about what their goals are, what their interests are. You can help point them in the right direction. As I said, I think that we can generally really improve how we treat this condition, which are the small renal masses. There's a lot of greater philosophic questions that I would pose like is it acceptable to accidentally remove a benign kidney tumor nowadays?
Let's say, hypothetically, you can know with high certainty whether or not a tumor is benign based on this biopsy or a PET scan or an MRI, whatever it is, is it acceptable to say, "Oh, sorry, we took out your benign tumor"? That's one question. I think we should have a greater discussion about this. Which patients benefit from treatment of indolent tumors? If we have said that, "Listen, there's a fairly large group of patients who have small renal masses that we think are indolent. There's been several studies showing that indolent tumors behave indolently. They are not aggressive. They rarely, if ever, metastasize or cause cancer-specific death, should we be treating these aggressively? If so, for which patients? Young patients? All patients?" Then, lastly, can a biopsy help us avoid this concept of overtreatment?
I think over-diagnosis is going to be hard to fix. That's not really within our control. We're not screening for these tumors. These people are showing up in our clinic after having a CAT scan for something else. What is in our control is how we manage that patient. I would argue that there is an element of over-treatment right now, and it has been going on for years and decades. Can something like a biopsy help us turn that back, help us spare patients unnecessary treatments? You know what, maybe. Some of these studies that we talked about already suggest that perhaps it can. I think that's a laudable goal, frankly.
[Dr. Aditya Bagrodia]
I don't know why. I guess this is my own bias. For prostate cancer, it's pretty easy to convey that, maybe because there's so much press out there on overtreatment and men that have been maimed because of the functional consequences. Maybe that's a part of it because there's a pretty substantial functional consequence. For some reason, kidney cancer, I don't know why, it's inexplicable to me, seems both for providers and patients a little bit harder to wrap their brain around nonintervention. I could spell tell you whatever you want, frame it. Just over the course of what you were saying a second ago, is it acceptable to remove a benign tumor?
I had a super fit 79-year-old patient, 6.5 centimeter on mass. Didn't look like a classic spoken wheel or whatever. I was like, "All right, you're fit. Your other kidney looks fine. We'll do a radical nephrectomy, stay in the hospital a day, and you're back to it." It was an oncocytoma. I was just like, "Oh my God, that's terrible." Thank God, she did fine, but what if she didn't? That would have been absolutely a catastrophe. Like you mentioned, I think we're continuing to learn. If I biopsied her and it didn't come back as a clear-cut oncocytoma here, I would twiddle my thumbs again. That's one end of the spectrum, healthier elderly patients that are fit enough to receive an intervention.
Then the young ones, I also find it a little bit tough. Something small, 1% chance risk of metastases. If you monitor it, the likelihood of it going gangbusters in four to six months is small, but it just seems that the acceptance of surveillance is a little bit more challenging. I think a biopsy could help galvanize that.
[Dr. Christopher Anderson]
Definitely. In fact, the minority of small renal masses are managed with surveillance right now, for many of the reasons that you already discussed. What's the right amount of surveillance? We've defined this for prostate cancer, right, that in Europe, they're doing a great job on surveillance and we're still catching up. At least the most recent data would suggest that we're still aggressively treating a fair amount of patients with grade 1 prostate cancer, whereas they're not doing that overseas. What's the right amount of surveillance for small renal masses, and what are the right patients for that? I think that getting better information can help inform that question. A biopsy. There's many emerging tissue-based biomarkers, I think, that probably are going to be playing, hopefully, a bigger role here going forward, where they can give us a better estimate of a disease biology and aggressiveness, maybe apart from what histology shows alone. This is what we've been doing with prostate cancer for years. Why can't we do it for kidney cancer? Perhaps we can, and perhaps we will.
[Dr. Aditya Bagrodia]
I was going to ask what gets you excited. Tissue-based biomarkers, I think, non-invasive tests, things are moving at a pretty breakneck speed. Cell-free DNA. Maybe you pick up on BAP1 mutations for a small renal mass and say, "Okay, it's time to go," or there are some mutations associated with indolent clinical behavior, and you can sit tight and potentially obviate some of those invasive tests, as it were.
[Dr. Christopher Anderson]
Absolutely. I think there's a lot of hope that we can do something in the tissue of a kidney tumor, particularly a cancerous one, that we can glean from a biopsy that will give us a lot of that information. That, "Hey, listen, you're 55, but you have a indolent appearing tumor with a low cell cycle progression score," or whatever other tissue-based biomarker we happen to have at that time. I think that that can provide a lot of reassurance to the patient and maybe help him or her make a decision. Now, to your point, though, what are the risks here? What are the stakes? A partial nephrectomy, we're really good at these. We're really good at robotic partial nephrectomies.
Our interventional radiologists are really good at ablations. We can remove these tumors or ablate them with minimal risk, but it's not zero risk. I think we still have to consider the fact that these are not completely harmless surgeries. They do put people out of work for a couple of weeks. They have incisional pain. There's a low chance of bleeding or urine leaks or injury to something around the kidney, and that's not trivial, even though it's very rare.
The Big Picture in Risk Stratification
At a broader level risk stratification seeks to determine which small renal masses truly require treatment and which can be safely observed. As imaging technology continues to uncover incidental findings, physicians must balance the risk of overtreatment against the danger of overlooking aggressive disease. The challenge is to deliver care that is both cautious and evidence-based, avoiding unnecessary intervention without compromising safety. Effective risk stratification incorporates not only tumor characteristics but also patient goals, comorbidities, and life expectancy. The growing role of renal mass biopsy and emerging biomarkers is refining how clinicians interpret tumor biology, offering more personalized insights into disease behavior.
Ultimately, the purpose is precision in intervention planning, directing treatment toward the minority of renal masses that pose genuine clinical risk while sparing patients from avoidable surgery, anxiety, and loss of renal function. By integrating data, judgment, and patient values, clinicians can ensure that management decisions remain both individualized and meaningful.
[Dr. Aditya Bagrodia]
I like the idea though, for the higher risk for a non-diagnostic with the criteria that you shared. You prefaced it so it's not something done wrong or things along those lines. It's just like, "Hey, this happens, it happened to you, and we were going to sort it out." Maybe just running through a couple of case scenarios, so central hilar tumors. Do you like biopsying those?
[Dr. Christopher Anderson]
I am wary of tumors in challenging locations. I think that there are risks of biopsy, which are probably much higher if you're doing it right around the hilum, around the vasculature may not be worth it in that case.
[Dr. Aditya Bagrodia]
I struggle with this one because I absolutely share those concerns, but then, for instance, I sure don't want to do a radical nephrectomy if it's a potentially super-- most of the time, you can shell it out and it works out, but I'd like to know that I'm removing a cancer if there's more than the standard 1% to 5% chance conversion into radical. If I'm thinking there's a 15%, 20% chance this kidney is going to be in a bucket, I'd like to know that it was cancer.
[Dr. Christopher Anderson]
I'm with you. Again, I'm very much pro-biopsy. I just think you have to pick your battles a little bit. There are patients where you shouldn't have a biopsy, you're on anticoagulation. We talked about you're very old and infirm, a very difficult tumor to reach, anterior tumors that you'd have to traverse the liver or another organ to get to. We're not talking about biopsying those ones because I think the risks are probably undue.
Now, there have been some creative ways of doing biopsies. There have been endoscopic trans-duodenal biopsies. I've seen those being done. Those are pretty uncommon. If it was that important to do, it can be done. Not every tumor is amenable to a safe biopsy. I think that's just the facts of life at this time.
[Dr. Aditya Bagrodia]
I'd never really thought about it, but obviously for pancreatic masses and pulmonary nodules, they do endobronchial biopsies. Why not? You had mentioned, "I haven't done biopsies for upper tract." Are you actually doing biopsies?
[Dr. Christopher Anderson]
I am personally not. Although there are urologists who are doing them in clinic under ultrasound-guided successfully, safely. They're publishing on this. It's something that I think we all should be taking notice of. You'd mentioned prostate biopsy. We do prostate biopsies without any concern. This is all ultrasound-guided. We're all very good technicians. Transperineally, we can use image guidance now.
Should kidneys now be part of our repertoire? Maybe. I think if renal mass biopsy turns out to be something that is really more accepted and something that we all advocate for our patients getting, then it's something that we could consider integrating into our own practices. There's a little bit of a learning curve, but it's not insurmountable.
[Dr. Aditya Bagrodia]
I'm having flashbacks of my early transperineal days. I've got partners that do ultrasound-guided percutaneous access for their PCNLs, and again, not the focus of this conversation, but wouldn't it be nice if you have this old infirm patient with obstructive pyelonephritis, you ultrasound them, pop it into a frost tube, and get on with it, versus the whole coordination with other services and whatnot?
I don't know that that's where I'm going to spend my efforts imminently, but there's also pretty cool technologies bringing in MRIs into the office where say, for instance, you didn't feel super comfortable with ultrasound-guided biopsy, you have a renal mass, nearly certainly with an MRI or something cross-sectionally, super helpful. Complex hilar tumors, jury's out, case-specific. That sounds reasonable to me. Young patients. Maybe I'll just explain my thought process. Do I want to consider doing a radical versus a partial for small renal mass, and do I want to consider doing a lymph node dissection? I would like to know if I'm dealing with something HLRCC or other medullary aggressive variant. How do you feel about that, Chris?
[Dr. Christopher Anderson]
That's not always the reason I necessarily would recommend a biopsy, whether we should do a radical versus partial. Can you do a partial nephrectomy on a high-grade tumor? Yes, you can do that. Lymph node dissection, I think that's probably a different discussion. Should we do any lymph node dissections, on which patients, high-grade? Should any patient get a lymph node dissection who's clinically node-negative? Perhaps, yes.
Maybe if we knew that you were very high-risk and we could quantify that or characterize that before surgery, maybe we should be selecting those patients for lymph node dissections. A lot of unanswered questions there. I think that, in my mind, the main role at this point for a biopsy is to help both the doctor and the patient be swimming in the same direction. I think this is useful for shared decision-making.
We did a little bit of work on this and published a small study where we actually asked doctors and patients before and after a biopsy about what treatment they want and were interested initially, how confident they were. What we found was somewhat surprising that actually, all the patients felt the biopsy was important, and it really helped them improve their decision-making. It also helped the doctors improve their decision-making. There was a much higher concordance in the treatment recommendation and treatment selection after the biopsy compared to before.
I think that was eye-opening and very validating to us. I worked on this with a couple of my residents. We all learned a lot from this, and I think we have been using this to counsel patients going forward saying, "Listen, if you're having a hard time making this decision, I just threw a whole bunch of statistics at you. You might have a surgery for benign, maybe we can watch it, but it's 10% chance it's aggressive. Maybe we can just do a procedure, get that information, and it will help you make a more informed decision."
[Dr. Aditya Bagrodia]
I generally quote about 1% risk of bleeding or something along those lines. Sound okay?
[Dr. Christopher Anderson]
Yes, I think that's about right.
[Dr. Aditya Bagrodia]
All right. You've mentioned some of the challenges, non-diagnostic rates, those are tough. Some of them are going to be inaccessible, or anticoagulation, or retrorenal colon, or some other anatomic scenario. One of my least favorites is oncocytic neoplasm.
[Dr. Christopher Anderson]
Oh, man.
[Dr. Aditya Bagrodia]
What do you do with that, Chris?
[Dr. Christopher Anderson]
Those are the worst, aren't they? It frustrates you a lot. This is also a limitation of the biopsy where you get a wishy-washy read. Even the best pathologist can give you this kind of uncertain diagnosis that either this is an oncocytoma or perhaps a chromophobe renal cell carcinoma. First of all, it's been shown that these tumors, in general, have a very favorable prognosis.
Even if you chose to survey an oncocytic tumor that actually was a small chromophobe renal cell carcinoma, those tend to do very, very well. I think, overall, the stakes are lower. It depends a little bit on the individual patient and the risk tolerance, but it's a favorable risk group. There is a chance that you're sitting on a cancer that has not been proven to be cancerous, but at least you know, in general, that this is not something that's going to be urgently dangerous.
[Dr. Aditya Bagrodia]
I appreciate that. I think it's just another bit of information that allows you to diffuse some of the anxiety and say, "Even if we deal with the cancer, likelihood of this being a dangerous cancer is exceedingly low. We're not dismissing you. We're going to monitor it, and then if the growth kinetics or the size or the appearance or whatever changes, we either pull the trigger, do something, or repeat a biopsy."
[Dr. Christopher Anderson]
Absolutely.
Podcast Contributors
Cite This Podcast
BackTable, LLC (Producer). (2023, November 3). Ep. 134 – The Role of Renal Mass Biopsy in Modern Urology [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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