Localized cT1b or larger renal tumors managed with active surveillance are associated with tumor growth rates and mortality rates similar to those managed with surgery, a study published in the Journal of Urology has shown.1

According to the American Cancer Society, kidney cancer is among the 10 most common cancers in both men and women, and it is estimated that there will be over 61,000 new cases of kidney cancer and approximately 14,000 kidney cancer-related deaths in the United States in 2015. The average age of patients who receive a kidney cancer diagnosis is 64.2

Current National Cancer Comprehensive Network (NCCN) guidelines recommend a partial or radical nephrectomy as primary treatment for T1b kidney cancer and radical nephrectomy for stage II kidney cancer. The guidelines do not recommend active surveillance for these patients.

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For patients with stage T1b tumors, patients are to be monitored every 6 months for 2 years, then annually for up to 5 years following nephrectomy.3

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Procedures include nephron-sparing surgery, laparoscopic radical nephrectomy, and laparoscopic/robotic partial nephrectomy.1 Systemic therapy is only to be used in the case of relapse.

Although there is evidence showing the growth rate and outcomes of untreated T1a renal masses, it is unclear whether untreated patients with renal masses larger than 4 cm in diameter would benefit most from active surveillance or definitive intervention.

Therefore, researchers at Icahn School of Medicine at Mount Sinai in New York, New York, sought to assess the growth kinetics and outcomes of cT1b/T2 cortical renal masses treated with an initial period of close monitoring.1

Researchers identified 68 patients with a total of 72 tumors 4 cm or greater in diameter. The median age of all patients was 70 (range 40-94).

At presentation, the median tumor size was 4.9 cm with a mean linear growth rate of 0.44 cm per year. All patients were initially managed expectantly for 6 months. Of those enrolled, 66% continued to be treated with active surveillance while 34% progressed to intervention.1

Results showed that of the 72 lesions larger than 4 cm at presentation, the mean linear growth rate was 0.44 ± 0.45 cm per year and 14.7% demonstrated no growth during the mean 38.9 ± 25.7 months of follow up.

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Of those that progressed to definitive intervention, 61% were due to interval tumor growth, 26% because of patient choice, 4% due to medical clearance, and 4% as a result of the development of tumor-related symptoms. Multivariate analyses showed that patient age (OR = 0.91; 95% CI: 0.86-0.97) and linear growth rate (OR = 9.1; 95% CI: 1.7-47.8) were significantly associated with delayed intervention.1

Although the authors make note of the selection bias, small sample size, and poor generalizability of the study, the findings suggest that an initial period of active surveillance to assess growth kinetics of a patient’s renal tumors larger than 4 cm is a suitable option in certain patients that may be at risk for surgical complications following definitive intervention due to their age or comorbidities.1


  1. Mehrazin R, Smaldone MC, Kutikov A, et al. Growth kinetics and short-term outcomes of cT1b and cT2 renal masses under active surveillance. J Urol. 2014;192(3):659-664.
  2. “What are the key statistics about kidney cancer?” American Cancer Society. 13 Jan 2015. Web. 04 Feb 2015.
  3. NCCN Clinical Practice Guidelines in Oncology™. Kidney. v 3.2015. Available at: http://www.nccn.org/professionals/physician_gls/pdf/kidney.pdf. Accessed February 4, 2015.