Point: Renal mass biopsy: Is it necessary for localized tumors?

The role of renal mass biopsy may be best viewed in the context of modern treatments for cancer, which have moved away from a “one-size-fits-all” model toward precision treatments that are based on patients and their individual tumor characteristics, according to E. Jason Abel, MD.

“The simplest way to implement precision treatment for patients with small renal masses is to use biopsy up front to improve decision-making,” said Dr. Abel, associate professor of urologic oncology at the University of Wisconsin School of Medicine and Public Health, Madison.

Patients diagnosed with small renal masses have multiple options for treatment, including surgery, thermal ablation, and active surveillance. Having more information up front can help patients to make an informed decision, he noted.

Related - Counterpoint: Renal mass biopsy: Is it necessary for localized tumors?

Increasingly, members of the urology community believe that choosing the best treatment solely on radiographic information is an “under-informed” approach for many patients, Dr. Abel added.

Biopsies safe, inexpensive

Renal mass biopsy is generally safe, relatively inexpensive, and should be discussed with most patients, as it is a tool that can provide information to guide treatment decision-making.

“If you use a biopsy to distinguish between ‘cancer’ and ‘not cancer,’ you’ve still improved your overall outcomes by deferring active treatments in patients with benign tumors,” Dr. Abel said.

At minimum, biopsy allows identification of benign renal tumors, and nephrectomy can be avoided in many patients who will be spared the impact of poor renal function later in life.

However, not all patients need to have a biopsy before treatment, and in fact, approximately 30% to 40% of the renal mass patients in Dr. Abel’s practice are currently treated surgically without a biopsy up front.

Even so, biopsies should be discussed with most patients, according to Dr. Abel, who views biopsy as a safe and relatively inexpensive tool that can provide information to guide treatment choices.

In fact, perhaps the most compelling reason to offer biopsy is not even scientific or medical: Biopsy provides more information and thereby improves the informed consent process. “Regardless of the subsequent treatment, biopsy empowers physicians and patients to make better decisions,” Dr. Abel said.

Next: What the guidelines say

What the guidelines say

Expert thinking on renal mass biopsy has evolved considerably in recent years, Dr. Abel acknowledged.

Read - Point: Is stand-alone white light cystoscopy a thing of the past?

A current recommendation from the AUA states that renal mass biopsy is not required for young or healthy patients unwilling to accept the uncertainties associated with the procedure, and older or frail patients who will be managed conservatively regardless of biopsy findings. That recommendation, based on expert opinion, appears in the AUA’s 2017 guideline on renal mass and localized cancer.¹

In the context of that recommendation, it’s important to consider that, per the American Cancer Society, the mean age of renal cell cancer diagnosis is 64 years, so a typical patient presenting with a small renal mass is not necessarily a healthy young patient, nor an older, sicker patient, Dr. Abel noted.

Instead, that “typical patient” may provide an illustration of the benefits of renal mass biopsy.

Dr. Abel described a hypothetical patient, a 64-year-old obese man who presents to the clinic with a centrally located, 2-cm endophytic renal mass.

“We know from population-based studies that radical nephrectomy is still the most common treatment for small central renal tumors in this situation,” he said. “However, we also know that statistically, a small kidney cancer is very unlikely to cause this gentleman’s death.”

For that patient, based only on radiographic information, the clinician may be limited to discussing data that, depending on tumor size, 20% to 30% of clinically localized renal masses may be benign.²

The biopsy would provide extra information to guide decision-making.

If the biopsy yields benign pathologic findings, the patient may be appropriately counseled toward surveillance. Conversely, if the patient is considering active surveillance and a biopsy shows high-grade cancer, that information could help drive the decision for surgery, Dr. Abel said.

Also see: Counterpoint: Is stand-alone white cystoscopy a thing of the past?

“I think we really need to move away from the idea that we know what’s best for each individual patient after just looking at imaging,” Dr. Abel said. “Biopsy is safe, it’s relatively inexpensive, and it provides more information, and I think we really need to evolve as a field to consider this as an approach to shared decision-making.”

Next: Risks and benefits

Risks and benefits

To understand the evolving role of biopsy and treatment of small renal masses, it may be helpful to draw an analogy to low-risk prostate cancer treatment, which has evolved significantly in the last few decades, according to Dr. Abel.

The 10-year estimated cancer-related mortality in low-risk prostate cancer is similar to what has been reported for small renal cell carcinomas, and the median age of diagnosis is 66 years for prostate cancer versus 64 years in renal cell cancer, according to recent American Cancer Society estimates.

“Just like we learned in low-risk prostate cancer, many patients will die from causes other than kidney cancer, especially patients who are older and more comorbid,” Dr. Abel said. “I think we should focus on treating patients who are most likely to benefit from treatment, and for the vast majority of patients, there’s really no reason to rush into treatment.”

Bleeding and tract seeding are two objections to increased use of renal mass biopsy that have been raised. However, despite being the most significant concern, the risk of significant bleeding after biopsy is less than 1% in some large series. Indeed, the AUA guidelines acknowledge that renal mass biopsy is “generally safe with a low risk of complications.”

Moreover, the guidelines address another concern that has been raised regarding renal mass biopsy: the risk of tumor seeding, a risk that Dr. Abel calls “theoretical.” Using contemporary techniques, there have been no reported cases of tumor seeding, the guidelines state.

Given the established safety and the fact that the procedure is relatively expensive, the question may not be, “Is renal mass biopsy necessary?” but rather, “Why would you not collect more information for a patient who is facing what may be a difficult decision?”

“Biopsy up front allows us to focus our surveillance on a targeted population; namely, patients who have cancer,” Dr. Abel concluded. “Biopsy spares one in four patients the anxiety of having a cancer diagnosis. It spares one in four patients the time and cost of many years of radiographic follow-up for a benign tumor.

“Conversely, if you identify a rare, aggressive tumor, the treatment plan is going to be adjusted up front. So there are definitely benefits to identifying cancer before committing to years of active surveillance.”

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References

1.  Campbell S, Uzzo RG, Allaf ME, et al. Renal Mass and Localized Renal Cancer: AUA Guideline. J Urol 2017; 198:520–9.

2.  Johnson DC, Vukina J, Smith AB, et al. Preoperatively misclassified, surgically removed benign renal masses: a systematic review of surgical series and United States population level burden estimate. J Urol 2015; 193:30-5.

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