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Patients with small renal masses avoided interventions in 70% of cases during about 3 years of active surveillance that had a standard protocol to identify progression requiring intervention, investigators reported.

During 31-34 months of follow-up, 37 of 123 patients met criteria for intervention, and 29 of the 37 underwent delayed intervention. The cohort had a 3-year freedom from progression to intervention of 72% and freedom from delayed intervention of 75%. No patient developed metastasis.

A majority of patients who progressed to intervention had more aggressive tumor characteristics at surgery, reported Eric C. Kaufman, MD, of Roswell Park Comprehensive Cancer Center in Buffalo, New York, and colleagues in the .

"Active surveillance using predefined progression criteria for intervention in otherwise unselected patients with small renal masses allows intervention to be focused on at-risk small renal masses with common adverse pathology, avoiding treatment for most patients with small renal masses," the authors concluded. "Long-term delayed intervention and oncologic safety require study."

Most clinically localized small renal masses are indolent and associated with slow growth and low metastatic potential. An accumulation of evidence has shown frequent overtreatment of the small masses, the authors noted. The historical "gold standard" for management of small renal masses has been surgical resection, although the masses's low oncologic risk often is outweighed by treatment-associated adverse events and complications.

Multiple studies have demonstrated the safety of active surveillance for small renal masses, delaying treatment for more than 12 months in many patients, they continued. The American Urological Association (AUA) and European Association of Urology recommend active surveillance as an option for older and less healthy patients with small renal masses, and the AUA also has recommended active surveillance as an option for younger/healthier patients.

Despite professional support, adoption in clinical practice has been slow, outpaced by adoption of robotic interventions, the authors said. Additionally, use of active surveillance has been slowed by unclear progression criteria and rates of delayed intervention in healthy patients as a result of selection bias toward older, less less fit patients in prior series.

Active surveillance offers the potential to improve oncologic risk stratification by assessment of tumor growth dynamics associated with the metastatic potential, Kaufman and colleagues continued. In about a third of patients, surveillance shows no growth, and metastatic risk remains low when a growing renal mass remains smaller than 4 cm in association with an average or slow growth rate. Surveillance may also facilitate percutaneous biopsy, which reveals benign neoplasia in 20% to 30% of small renal masses.

The authors reported findings from an ongoing active surveillance program recommended to all non-dialysis patients with small, nonmetastatic renal masses, regardless of age or health status, so long as they do not meet predefined progression criteria for intervention.

The surveillance protocol included standard imaging at baseline and 6 months for patients with tumors <3 cm or every 3 months for tumors ≥3 cm. Serial imaging continues every 6 to 12 months to assess tumor stability for 2 to 3 years. Percutaneous biopsy is recommended for masses >2 cm or masses <2 cm with a growth rate >5 mm/year.

Progression criteria for intervention consisted of small mass-related symptoms, unfavorable histology, stage T3a, or any of the following without benign biopsy results: diameter >4 cm; growth rate >5 mm/year for tumor diameter ≤3 cm; or >3 mm/year for tumor diameter >3 cm.

Over a 45-month period from 2013 to 2017, investigators identified 128 small renal masses, 123 (96%) of which did not meet progression criteria for intervention. During a median follow-up 31 months (mean of 34 months), no metastatic progression occurred and 30% of the 123 patients met progression criteria for intervention.

Subsequently, 29 of 37 patients who met progression-to-intervention criteria underwent delayed surgery. Pathology showed that 62% of the tumors were pT3 and/or nuclear grade 3-4 malignancy. None of the resections revealed benign pathology.

The study adds another dataset to the evidence base showing the safety of active surveillance and "showcases how it allows patients to avoid unnecessary treatment," said Alexander Kutikov, MD, of Fox Chase Cancer Center in Philadelphia, who was not involved in the study.

"What is notable about this publication is that it included all-comers regardless of age or comorbidity profile," Kutikov told 番茄社区. "Patients with tumors <4cm in size and those that don't exhibit rapid growth kinetics represent the best candidates for active surveillance. Indeed, median tumor size was 2.2 cm and rapid growth kinetics triggered intervention in this single-surgeon experience from Roswell Park."

Active surveillance also helps mitigate the "treatment disconnect" in renal cell carcinoma (RCC) -- a paradoxical rise in overall and cancer-specific mortality despite increased detection and treatment, Kutikov added. A , identified in the NCI Surveillance, Epidemiology, and End Results registry database, showed that a rapidly rising incidence, combined with imputations to account for missing data, can affect the resulting mortality statistics.

The authors acknowledged several limitations of the study: single-institution dataset, limited follow-up for long-term metastasis and intervention rates, and no comparison of outcomes with surgery versus other interventions.

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