Active surveillance found viable for small renal masses

Key Points

Kyoto, Japan-Early results from a registry of patients with small renal masses support the safety of active surveillance using a standardized protocol, report researchers from Johns Hopkins University's James Buchanan Brady Urological Institute, Baltimore.

The Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry was opened on Jan. 1, 2009, and is a multi-institutional project following small renal mass (SRM) patients who elect management by primary intervention or active surveillance. Eligible patients must be 18 years of age and older with a solid enhancing renal mass ≤4 cm, a good axial image on computed tomography or magnetic resonance imaging, and no history of renal cell carcinoma, familial RCC syndrome, or suspicions of metastatic disease.

Co-author Phillip M. Pierorazio, MD, reported outcomes collected through 34 months for 276 patients enrolled at three institutions: Johns Hopkins; the University of North Carolina, Chapel Hill; and Columbia University, New York. There were 187 patients who chose primary intervention and 89 in the active surveillance group; 13 of the latter patients had undergone delayed intervention.

Long-term follow-up planned

"These outcomes support active surveillance as a reasonable option for management of SRMs, especially for patients who are older, sicker, and have more complex tumors. However, the data are just short term, and follow-up to at least 5 years is planned," said Dr. Pierorazio, a urology resident at Brady Urological Institute, working with Mohamad E. Allaf, MD.

"Hopefully, the data collected will also allow us to define objective criteria for recommending active surveillance and delayed intervention and even to support conducting a prospective, randomized clinical trial."

The DISSRM registry was created to address the lack of prospective data on outcomes of patients with SRMs and concern about overtreatment of the growing number of patients found incidentally to have these lesions.

"There is a lot of data from retrospective studies supporting active surveillance for SRMs. Although it is not a randomized study, by following patients closely and with a standardized protocol, hopefully our registry will overcome some of the limitations of the retrospective data," Dr. Pierorazio said.

As expected, when compared with the primary intervention patients, the active surveillance group was significantly older with a significantly smaller mean tumor size, higher Charlson comorbidity index, and worse performance status. Education status, body mass index, incidence of prior surgery, and rates of symptomatic versus incidental presentation were not different between the two groups. There were also no between-group differences in 3-D tumor size or renal nephrometry score.

Pathology findings for the primary intervention group showed RCC in 76% of patients and other malignancy in 1%; almost half of the RCCs were clear cell carcinomas and about 70% were low-grade (1-2) tumors.

Among active surveillance patients, the median tumor growth rate was 0.12 cm/year. Dr. Pierorazio noted that the main trigger for recommending delayed intervention is a growth rate >0.5 cm, although some patients meeting that criterion opted to continue active surveillance, and the majority of patients (77%) who underwent delayed intervention did so because of personal preference. Of the three patients who had delayed intervention with a growth rate >0.5 cm/year, two were found to have RCC.

"While retrospective data has demonstrated linear and volumetric growth to indicate the risk of metastases, we have not been able to associate growth rate with progression at this point. We do know from retrospective data that the risk of metastasis increases once tumor size reaches 3 cm and then increases even more if it is 4 cm. However, time will tell whether overall size is the most important feature," Dr. Pierorazio said.