Can Biopsy Help Avoid Surgery for Small Kidney Tumors?

Can Biopsy Help Avoid Surgery for Small Kidney Tumors?

(By Jeni Crockett-Holme)

Keywords: Kidney cancer, Biopsy, Diagnosis, Treatment, Active surveillance

Kidney surgery is associated with a number of complications that result in illness and affect quality of life. Nevertheless, surgery for small kidney tumors provides excellent survival and is often performed based only on imaging results, which do not provide information about a tumor’s aggressiveness. A concern is that this surgery may be unnecessary, and some patients may be overtreated. Up to 30% of small kidney tumors are noncancerous and do not require treatment [1].

The study
Biopsy involves using a needle to remove a small piece of tissue from a tumor and examining the tissue [2]. Biopsy of small tumors in the kidney is reported to be both safe and accurate for determining whether tumors are cancerous [1]. Knowing whether a tumor is cancerous (malignant) or noncancerous (benign) can guide treatment decisions.

Researchers at the University of Toronto wanted to explore the usefulness of biopsy for diagnosing and treating small kidney tumors [1]. To examine the accuracy, safety, and impact of kidney tumor biopsy on treatment, they looked at the medical records of 509 patients who were treated for small kidney tumors between 2001 and 2013. A total of 529 biopsies were performed in these patients (some needed more than one biopsy) to help make decisions about treatment.

Results
Biopsy accurately diagnosed cancer in 94% of small kidney tumors, and 26% were found to be noncancerous. Tumor size and location on the kidney surface were characteristics specifically associated with diagnosis. Most patients were medically monitored with active surveillance or received other nonsurgical therapy. Surgery was performed in 175 patients, including 3 with tumors that biopsy identified as noncancerous and that proved to be noncancerous. Surgical findings agreed with biopsy information in 93% of cases, although biopsy tended to underestimate cancer grade (Fuhrman grade). Serious complications from biopsy occurred in less than 1% of patients.

What do the results tell us?
The results suggest that physician concerns about the accuracy, safety, and usefulness of kidney tumor biopsy are probably unfounded. Biopsy for small kidney tumors allowed safe, accurate diagnoses that provided information for treatment decision making.

Practical implications
The results of this study support the use of biopsy for diagnosis of patients with small kidney tumors. The information provided by kidney tumor biopsy can help determine who is a good candidate for medical monitoring and perhaps avoid unnecessary treatment. This approach has also been shown to be cost effective. Given these benefits, a shift in the surgical approach to small kidney tumors may be warranted.

[1] Richard PO, Jewett MAS, Bhatt JR, et al. Renal tumor biopsy for small renal masses: a single-center 13-year experience. Eur Urol 2015;68:1007–13.

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