Related Experiment Video
Updated: Jul 6, 2026

Point-of-Care Kidney and Genitourinary Ultrasound in Adults: Image Acquisition
Published on: June 21, 2024
Watchful waiting for small renal masses
Kamal Mattar1, Michael A S Jewett
1Department of Surgery/Urology, Princess Margaret Hospital, University of Toronto, 610 University Avenue, 3-124, Toronto, ON, M5G 2C4, Canada.
Abstract:
Small renal masses (SRMs; < 4 cm in diameter) account for most renal tumors treated today. Incidental early detection of SRMs by abdominal imaging results in favorable grade and stage migration to renal cell carcinoma, and also increases detection of benign renal tumors. As a result, most SRMs manifest indolent biological behavior with excellent prognosis. Despite the increased use of minimally invasive laparoscopic surgery, nephron-sparing techniques, and percutaneous ablation therapy, selected patients are managed by initial active surveillance, reserving therapy for progression. Older patients and those with competing risks due to medical comorbidities are excellent candidates for active surveillance; their risk of early progression due to growth or metastases appears to be low. Active surveillance should not be recommended for younger, healthier patients until prognostic factors are better defined. Needle core use for improved histopathologic characterization of SRMs should be considered before recommending treatment.
Insights
Small renal masses (SRMs) are often indolent, making active surveillance a viable option for older patients. Further research is needed to define prognostic factors for younger patients before recommending surveillance.
Area of Science:
- Urology
- Oncology
- Radiology
Background:
- Small renal masses (SRMs), defined as renal tumors < 4 cm, represent the majority of treated renal tumors.
- Incidental detection via abdominal imaging leads to earlier diagnosis of renal cell carcinoma and benign renal tumors, often with favorable characteristics.
- SRMs typically exhibit indolent behavior and an excellent prognosis.
Purpose of the Study:
- To evaluate the role of active surveillance in managing small renal masses.
- To identify patient populations who are suitable candidates for active surveillance.
- To emphasize the importance of histopathologic characterization before treatment.
Main Methods:
- Review of current management strategies for small renal masses.
- Analysis of patient characteristics, including age and comorbidities, in relation to active surveillance suitability.
- Consideration of diagnostic techniques for histopathologic characterization.
Main Results:
- Active surveillance is a suitable option for older patients and those with significant medical comorbidities due to their low risk of early progression.
- Younger, healthier patients are not ideal candidates for active surveillance until better prognostic factors are established.
- Minimally invasive surgical and ablative therapies are increasingly used, but active surveillance remains an option for selected cases.
Conclusions:
- Active surveillance is appropriate for select patients with small renal masses, particularly older individuals with comorbidities.
- Further research is required to establish clear prognostic factors for younger, healthier patients before recommending active surveillance.
- Histopathologic characterization through needle core biopsy should be considered to guide treatment decisions for SRMs.
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