Active surveillance for renal cortical neoplasms

Factors predicting the active treatment of renal angiomyolipoma: 30 years of experience in two tertiary referral centers

Introduction and objective

This study aimed to identify clinical features representing predictive factors of active treatment (AT) compared to active surveillance (AS) for renal angiomyolipoma (AML).

Patients and methods

From 1990 to 2020, patients referred to two institutions for a renal mass and diagnosed with an AML based on typical features on CT were included in the analysis. The study population was divided into two groups based on the treatment received: active surveillance (AS) or active treatment (AT). Age, gender, tuberous sclerosis syndrome, tumor size, contralateral kidney disease, renal function, year of diagnosis, and symptoms at presentation were assessed as potential predictive factors of active treatment using a logistic regression model in univariate and multivariate analyses.

Results

In total, 253 patients (mean age 52.3 ± 15.7 years; 70% women; 70.9% incidentally diagnosed) were included in the analysis. One hundred and nine (43%) received AS, whereas 144 (57%) were actively treated. For univariate analysis, age, tuberous sclerosis complex syndrome, tumor size, symptoms at presentation, and contralateral kidney disease were found to be predictors of AT. Only tumor size (p < 0.001) and the year of diagnosis (p < 0.001) remained significant for multivariable analyses. The likelihood of being managed with AS evolved over the study period and was 50% and 75% when diagnosed before and after 2010, respectively. With respect to size, 4-cm and 6-cm tumors had a probability of 50% and 75% of being treated with AS, respectively.

Conclusion

The present analysis from a high-volume institution provides evidence that the management of renal masses with typical radiological features of AML has markedly changed over the last three decades with a trend toward AS over AT. Tumor size and the year of diagnosis were significant factors for the treatment strategies.

Evaluation of Growth Rates for Small Renal Masses in Elderly Patients Undergoing Active Surveillance

Background

As the adoption of active surveillance (AS) for small renal masses (SRMs) grows, the number of elderly patients enrolled for a prolonged period of time will increase. However, our understanding of comparative growth rates (GRs) in aging patients with SRMs remains poor.

Objective

To examine whether particular age cutoffs are associated with an increased GR for patients undergoing AS for SRMs.

Design setting and participants

We identified all patients with SRMs enrolled in the multi-institutional, prospective Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry since 2009 who elected for AS.

Outcome measurements and statistical analysis

Two definitions of GR were examined: GR from the initial image (GRi) and GR from the prior image (GRp). Image measurements were dichotomized based on patient age at the time of imaging. Multiple age cutoffs were examined: 65, 70, 75, and 80 yr. Mixed-effect linear regression examined the associations between age and GR, with controlling to account for multiple measurements from the same individual.

Results and limitations

We examined 2542 measurements from 571 patients. The median age at enrollment was 70.9 yr (interquartile range [IQR] 63.2-77.4) with a median tumor diameter of 1.8 cm (IQR 1.4-2.5). As a continuous variable, age was not associated with GRi (-0.0001 cm/yr, 95% confidence interval [CI] -0.007 to 0.007, p = 0.97) or GRp (0.008 cm/yr, 95% CI -0.004 to 0.020, p = 0.17) after adjustment. The only age thresholds associated with an increased GR were 65 yr for GRi and 70 yr for GRp. Limitations include the one-dimensional nature of the measurements used.

Conclusions

Increased age for patients on AS for SRMs is not associated with increased GRs.

Patient summary

We examined whether patients undergoing active surveillance (AS) exhibited accelerated growth of their small renal masses (SRMs) after a certain age. No demonstrable change was seen, suggesting that AS is a safe and durable management option for aging patients with SRMs.

Artificial Intelligence in Kidney Cancer

Artificial intelligence is rapidly expanding into nearly all facets of life, particularly within the field of medicine. The diagnosis, characterization, management, and treatment of kidney cancer is ripe with areas for improvement that may be met with the promises of artificial intelligence. Here, we explore the impact of current research work in artificial intelligence for clinicians caring for patients with renal cancer, with a focus on the perspectives of radiologists, pathologists, and urologists. Promising preliminary results indicate that artificial intelligence may assist in the diagnosis and risk stratification of newly discovered renal masses and help guide the clinical treatment of patients with kidney cancer. However, much of the work in this field is still in its early stages, limited in its broader applicability, and hampered by small datasets, the varied appearance and presentation of kidney cancers, and the intrinsic limitations of the rigidly structured tasks artificial intelligence algorithms are trained to complete. Nonetheless, the continued exploration of artificial intelligence holds promise toward improving the clinical care of patients with kidney cancer.

Active Surveillance of Small Renal Masses: A Systematic Review

BACKGROUND: Our goal is to review current literature regarding active surveillance (AS) of small renal masses (SRMs) and identify trends in survival outcomes, factors that predict the need for further intervention, and quality of life (QOL). METHODS: We performed a comprehensive literature search in PubMed and EMBASE and identified 194 articles. A narrative summary was performed in lieu of a meta-analysis due to the heterogeneity of selected studies. RESULTS: Seventeen articles were chosen to be featured in this review. Growth rate (GR) was not an accurate predictor of malignancy, although it was the characteristic most commonly used to trigger delayed intervention (DI). The mean 5-year overall survival (OS) of all studies was 73.6% ±1.7% for AS groups. The combined cancer specific survival (CSS) for AS is 97.1% ±0.6%, compared to 98.6% ±0.4% for the primary intervention (PI) groups, (p = 0.038). CONCLUSIONS: Short and intermediate-term data demonstrate that AS with the option for DI is a management approach whose efficacy (in terms of CSS) approaches that of PI at 5 years, is cost effective, and prevents overtreatment, especially in patients with significant comorbidities.

Natural history and growth kinetics of clear cell renal cell carcinoma in sporadic and von Hippel-Lindau disease

Background

To evaluate and compare the natural history and growth kinetics of sporadic clear cell renal cell carcinoma (ccRCC) with those of ccRCC in von Hippel-Lindau disease (VHL).

Methods

Sixty patients in the sporadic group with 61 tumors and 15 patients in the VHL group with 30 tumors whom all underwent delayed surgery after at least 12 months of active surveillance (AS) were enrolled to conduct a retrospective cohort study. The growth rate was calculated, and the growth kinetics between the sporadic and VHL groups were compared. The patient and tumor characteristics were reviewed, and their correlation with growth rate was analyzed.

Results

The mean growth rate of sporadic ccRCC was 0.91 cm/year (ranging from 0–4.74 cm/year) and that of VHL ccRCC was 0.47 cm/year (ranging from 0.04–1.89 cm/year). The growth rate of sporadic ccRCC showed a tendency of being faster than that of VHL ccRCC but did not reach statistical significance (P=0.07). The factors affecting the growth rate were different between the two groups. For VHL ccRCC, the only factor that correlated with growth rate was initial tumor diameter (P<0.001), but for sporadic ccRCC, the only factor was pathological nuclear grade (P<0.001).

Conclusions

The growth rate of VHL-associated ccRCC might be slower than that of sporadic ccRCC. Furthermore, we identified a disparity in growth kinetics between sporadic and VHL-associated ccRCC.

Available active surveillance follow-up protocols for small renal mass: a systematic review

PURPOSE

To evaluate follow-up strategies for active surveillance of renal masses and to assess contemporary data.

METHODS

We performed a comprehensive search of electronic databases (Embase, Medline, and Cochrane). A systematic review of the follow-up protocols was carried out. A total of 20 studies were included.

RESULT

Our analysis highlights that most of the series used different protocols of follow-up without consistent differences in the outcomes. Most common protocol consisted in imaging and clinical evaluation at 3, 6, and 12 months and yearly thereafter. Median length of follow-up was 42 months (range 1-137). Mean age was 74 years (range 67-83). Of 2243 patients 223 (10%) died during the follow-up and 19 patients died of kidney cancer (0.8%). The growth rate was the most used parameter to evaluate disease progression eventually triggering delayed intervention. Maximal axial diameter was the most common method to evaluate growth rate. CT scan is the most used, probably because it is usually more precise than kidney ultrasound and more accessible than MRI. Performing chest X-ray at every check does not seem to alter the clinical outcome during AS.

CONCLUSION

The minimal cancer-specific mortality does not seem to correlate with the follow-up scheme. Outside of growth rate and initial size, imaging features to predict outcome of RCC during AS are limited. Active surveillance of SRM is a well-established treatment option. However, standardized follow-up protocols are lacking. Prospective, randomized, trials to evaluate the best follow-up strategies are pending.

Small Renal Mass Surveillance: Histology-specific Growth Rates in a Biopsy-characterized Cohort

BACKGROUND

Most reports of active surveillance (AS) of small renal masses (SRMs) lack biopsy confirmation, and therefore include benign tumors and different subtypes of renal cell carcinoma (RCC).

OBJECTIVE

We compared the growth rates and progression of different histologic subtypes of RCC SRMs (SRM^RCC) in the largest cohort of patients with biopsy-characterized SRMs on AS.

DESIGN, SETTING, AND PARTICIPANTS

Data from patients in a multicenter Canadian trial and a Princess Margaret cohort were combined to include 136 biopsy-proven SRM^RCC lesions managed by AS, with treatment deferred until progression or patient/surgeon decision.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Growth curves were estimated from serial tumor size measures. Tumor progression was defined by sustained size ≥4 cm or volume doubling within 1 yr.

RESULTS AND LIMITATIONS

Median follow-up for patients who remained on AS was 5.8 yr (interquartile range 3.4-7.5 yr). Clear cell RCC SRMs (SRM^ccRCC) grew faster than papillary type 1 SRMs (0.25 and 0.02 cm/yr on average, respectively, p =  0.0003). Overall, 60 SRM^RCC lesions progressed: 49 (82%) by rapid growth (volume doubling), seven (12%) increasing to ≥4 cm, and four (6.7%) by both criteria. Six patients developed metastases, and all were of clear cell RCC histology. Limitations include the use of different imaging modalities and a lack of central imaging review.

CONCLUSIONS

Tumor growth varies between histologic subtypes of SRM^RCC and among SRM^ccRCC, which likely reflects individual host and tumor biology. Without validated biomarkers that predict this variation, initial follow-up of histologically characterized SRMs can inform personalized treatment for patients on AS.

PATIENT SUMMARY

Many small kidney cancers are suitable for surveillance and can be monitored over time for change. We demonstrate that different types of kidney cancers grow at different rates and are at different risks of progression. These results may guide better personalized treatment.

Renal imaging in 199 Dutch patients with Birt-Hogg-Dubé syndrome: Screening compliance and outcome

Birt-Hogg-Dubé syndrome is associated with an increased risk for renal cell carcinoma. Surveillance is recommended, but the optimal imaging method and screening interval remain to be defined. The main aim of our study was to evaluate the outcomes of RCC surveillance to get insight in the safety of annual US in these patients. Surveillance data and medical records of 199 patients with Birt-Hogg-Dubé syndrome were collected retrospectively using medical files and a questionnaire. These patients were diagnosed in two Dutch hospitals and data were collected until June 2014. A first screening for renal cell carcinoma was performed in 172/199 patients (86%). Follow-up data were available from 121 patients. The mean follow-up period per patient was 4.2 years. Of the patients known to be under surveillance, 83% was screened at least annually and 94% at least every two years. Thirty-eight renal cell carcinomas had occurred in 23 patients. The mean age at diagnosis of the first tumour was 51. Eighteen tumours were visualized by ultrasound. Nine small tumours (7–27 mm) were visible on MRI or CT and not detected using ultrasound. Our data indicate that compliance to renal screening is relatively high. Furthermore, ultrasound might be a sensitive, cheap and widely available alternative for MRI or part of the MRIs for detecting clinically relevant renal tumours in BHD patients,but the limitations should be considered carefully. Data from larger cohorts are necessary to confirm these observations.

Imaging Protocols for Active Surveillance in Renal Cell Carcinoma

PURPOSE OF REVIEW

To review the growth kinetics of small renal masses and available imaging modalities for mass characterization and surveillance, highlight current organizational recommendations for the active surveillance of small renal masses, and discuss the most recently reported oncological outcomes of patients as they relate to various surveillance imaging protocols and progression to delayed intervention.

RECENT FINDINGS

Overall, organizational guideline recommendations are broad and lack specifics regarding timing and modality for follow-up imaging of small renal masses. Additionally, despite general consensus in the literature about certain criteria to trigger delayed intervention, there exist no formal guidelines. Active surveillance of small renal masses is an acceptable management strategy for patients with prohibitive surgical risk; however, standardized imaging protocols for surveillance are lacking, as are randomized, prospective trials to evaluate the ideal follow-up protocol.

Imaging of Solid Renal Masses

The increase in serendipitous detection of solid renal masses on imaging has not resulted in a reduction in mortality from renal cell carcinoma. Consequently, efforts for improved lesion characterization have been pursued and incorporated into management algorithms for distinguishing clinically significant tumors from those with favorable histology or benign conditions. Although diagnostic imaging strategies have evolved for optimized lesion detection, distinction between benign tumors and both indolent and aggressive malignant neoplasms remain an important diagnostic challenge. Recent advances in cross-sectional imaging have expanded the role of these tests in the noninvasive characterization of solid renal tumors.

Role of Active Surveillance for Localized Small Renal Masses

CONTEXT

Stage migration of organ-confined renal masses is occurring as a result of incidental diagnosis, especially in the elderly. Active surveillance (AS) is gaining clinical traction as a treatment alternative to surgery and focal therapy.

OBJECTIVE

To assess contemporary data and evaluate AS risk trade-offs in the treatment of organ-confined kidney cancer.

EVIDENCE ACQUISITION

A comprehensive search of the Embase, Medline and Cochrane databases was carried out. A systematic review of the role of AS for organ-confined renal masses was performed. A total of 28 studies were included in the systematic review.

EVIDENCE SYNTHESIS

The median linear tumor growth rate for clinically localized renal masses (CLRMs) was 0.37cm/yr (interquartile range 0.15-0.7), with 0.22cm/yr in the cT1a subgroup and 0.45cm/yr in the cT1b--2 subgroup. The metastatic progression rate was 1-6% and was similar for cT1a (1-6%) and cT1b (0-5%); other-cause mortality for patients with CLRMs was 0-45% (1-25% for cT1a vs 11-13% for cT1b-2); cancer-specific mortality ranged between 0% and 18%. According to the 2011 Oxford scale, AS as a treatment option for CLRMs remains supported by level 3 evidence.

CONCLUSIONS

Although no randomized clinical data are available, current data support oncologic safety for AS in the management of CLRMs, particularly for small renal masses and among elderly and/or comorbid patients.

PATIENT SUMMARY

In this review we looked at the outcomes for patients with small kidney masses managed with surveillance. We found that surveillance is a safe initial option for tumors of less than 2cm, especially in elderly and sick patients.

Active Surveillance for Localized Renal Masses: Tumor Growth, Delayed Intervention Rates, and >5-yr Clinical Outcomes

BACKGROUND

Active surveillance (AS) has gained acceptance as a management strategy for localized renal masses.

OBJECTIVE

To review our large single-center experience with AS.

DESIGN, SETTING, AND PARTICIPANTS

From 2000 to 2016, we identified 457 patients with 544 lesions managed with AS from our prospectively maintained kidney cancer database. A subset analysis was performed for patients with ≥5-yr follow-up without delayed intervention (DI).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Linear growth rates (LGRs) were estimated using linear regression for the initial LGR (iLGR) AS interval and the entire AS period. Overall survival (OS) and cumulative incidence of DI were estimated with Kaplan-Meier methods utilizing iLGR groups, adjusting for covariates. DI was evaluated for association with OS in Cox models.

RESULTS AND LIMITATIONS

Median follow-up was 67 mo (interquartile range [IQR] 41-94 mo) for surviving patients. Cumulative incidence of DI (n=153) after 1, 2, 3, 4, and 5 yr was 9%, 22%, 29%, 35%, and 42%, respectively. Median initial maximum tumor dimension was 2.1cm (IQR 1.5-3.1cm). Median iLGR and overall LGR were 1.9 (IQR 0-7) and 1.9 (IQR 0.3-4.2) mm/yr, respectively. Compared with the no growth group, low iLGR (hazard ratio [HR] 1.25, 95% cumulative incidence [CI] 0.82-1.91), moderate iLGR (HR 2.1, 95% CI 1.31-3.36), and high iLGR (HR 1.87, 95% CI 1.23-2.84) were associated with DI (p=0.003). The iLGR was not associated with OS (p=0.8). DI was not associated with OS (HR 1.34, 95% CI 0.79-2.29, p=0.3). Five-year cancer-specific mortality (CSM) was 1.2% (95% CI 0.4-2.8%). Of 99 patients on AS without DI for >5 yr, one patient metastasized.

CONCLUSIONS

At >5 yr, AS±DI is a successful strategy in carefully managed patients. DI often occurs in the first 2-3 yr, becoming less likely over time. Rare metastasis and low CSM rates should reassure physicians that AS is safe in the intermediate to long term.

PATIENT SUMMARY

In this report, we looked at the outcomes of patients with kidney masses who elected to enroll in active surveillance rather than immediate surgery. We found that patients who need surgery are often identified early and those who remain on active surveillance become less likely to need surgery over time. We concluded that active surveillance with or without delayed surgery is a safe practice and that, when properly managed and followed, patients are unlikely to metastasize or die from kidney cancer.

Diagnostic Performance and Interreader Agreement of a Standardized MR Imaging Approach in the Prediction of Small Renal Mass Histology

Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio [OR]: 3.19; 95% confidence interval [CI]: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists. ^© RSNA, 2018 Online supplemental material is available for this article.

Management of Small Renal Masses

With the ubiquitous use of cross-sectional abdominal imaging in recent years, the incidence of small renal masses (SRMs) has increased, and the evaluation and management of SRMs have become important clinical issues. Diagnosing a mass in the early stages theoretically allows for high rates of cure but simultaneously risks overtreatment. In the past 20 years, surgical treatment of SRMs has transitioned from radical nephrectomy for all renal tumors, regardless of size, to elective partial nephrectomy whenever technically feasible. Additionally, newer approaches, including renal mass biopsy, active surveillance for select patients, and renal mass ablation, have been increasingly used. In this chapter, we review the current evidence-based papers covering aspects of the diagnosis and management of SRMs.

Active Surveillance in Small Renal Masses in the Elderly: A Literature Review

CONTEXT

Small renal masses have become increasingly common due to widespread imaging; however, optimal management of these lesions in the elderly can be complex due to the competing risks of intervention, natural history of disease, patient comorbidities, and expectations. In the properly selected elderly patient, active surveillance remains an accepted and attractive treatment approach.

OBJECTIVE

We completed a literature review of small renal masses (enhancing, <4cm, T1aN0M0 disease) in the elderly, aged ≥70 yr, aimed at identifying the utility of active surveillance in this population. The primary outcomes were conversion to active treatment while on active surveillance and cancer-specific mortality. Secondary outcomes included predictors of treatment, type of treatment performed (partial nephrectomy, radical nephrectomy, and ablation), progression to metastases, all-cause mortality, tumor growth rate, and demographic data including age and Charlson Comorbidity Index.

EVIDENCE ACQUISITION

A comprehensive search of electronic databases (e.g., MEDLINE, EMBASE, SCOPUS, Web of Science, and the Cochrane Library) using search terms "small renal mass" OR "SRM", AND "elderly," "senior," "aging," "geriatric," OR "octogenarian" was completed. All randomized controlled trials, nonrandomized comparison studies, and case series were included and screened by the reviewers. All comparison studies included in the systematic review were assessed for methodological quality using the Cochrane Risk of Bias tools.

EVIDENCE SYNTHESIS

Seventeen primary studies including 36495 patients met the inclusion criteria for the systematic review. All studies were retrospective institutional chart or the Surveillance, Epidemiology, and End Results database reviews. There was a low (4-26%) rate of conversion to active treatment for active surveillance in the identified studies over a follow-up interval of up to 91.5 mo. Overall mortality was substantial in this elderly cohort, with 15-51% of patients being deceased over the course of study follow-up; however, there was minimal cancer-specific mortality due to patients succumbing to alternative comorbid disease. In the future, patient comorbidity and biological age versus the natural history of the individualized tumor biology may play an increasing role in the discussion regarding treatment options and consideration of active surveillance.

CONCLUSIONS

Active surveillance is an effective management strategy in the elderly population. Few patients required the conversion to active treatment and there was low cancer-specific mortality. The majority of patients who expired over the course of the identified studies succumbed to alternative disease. The goal of treatment strategies should include weighing patient-specific prognosis relative to their competing health risks and treatment goals against the natural history of disease and risks of intervention.

PATIENT SUMMARY

In this review article, the authors examined the utility of active surveillance in the setting of a small localized renal mass in the elderly population. Despite being on surveillance, we found that cancer-specific outcomes were excellent, and overall mortality was often a result of comorbid disease. However, there is significant heterogeneity among elderly patients, and treatment approaches should be focused around patient-centered goals and prognosis.

Imaging and Screening of Kidney Cancer

Renal cell carcinoma (RCC) exhibits a diverse and heterogeneous disease spectrum, but insight into its molecular biology has provided an improved understanding of potential risk factors, oncologic behavior, and imaging features. Computed tomography (CT) and MR imaging may allow the identification and preoperative subtyping of RCC and assessment of a response to various therapies. Active surveillance is a viable management option in some patients and has provided further insight into the natural history of RCC, including the favorable prognosis of cystic neoplasms. This article reviews CT and MR imaging in RCC and the role of screening in selected high-risk populations.

Growth kinetics of small renal mass: Initial analysis of active surveillance registry

Purpose

To evaluate the clinical safety and natural history of active surveillance (AS) for incidentally diagnosed small renal mass (SRM).

Materials and Methods

We analyzed prospective data for patients who underwent AS for SRM. From 2010 to 2016, 37 SRMs of less than 3 cm were registered. Computed tomography (CT) and magnetic resonance imaging were used for initial diagnosis and CT, ultrasonography, and chest CT were performed at 6-month intervals. If there was no change in size during 2 years, follow-ups were performed annually. If the growth rate was more than 0.5 cm/y, if the diameter was more than 4 cm, or if clinical progression was observed, we regarded it as progression of SRM and recommended active treatment. We compared the growth rate and clinical course of SRM between patients who remained on surveillance and those who had progressed disease.

Results

The mean age was 63 years (range, 30–86 years) and the mean diameter was 1.8 cm (range, 0.6–2.8 cm) at diagnosis. The mean follow-up period was 27.3 months (range, 6–80 months) and the average growth rate was 0.2 cm/y (range, 0–1.9 cm/y). Six patients (16.2%) showed progression of SRM. Three patients wanted continuous observation, and partial nephrectomy was performed on 3 other patients. None of the patients had clinical progression, including metastasis.

Conclusions

We could delay active treatment for patients with an SRM with scheduled surveillance if the SRM grew relatively slowly. If more long-term AS results are documented for more patients, AS could be an alternative treatment modality for SRM.

Focal ablation therapy for renal cancer in the era of active surveillance and minimally invasive partial nephrectomy

Partial nephrectomy is the optimal surgical approach in the management of small renal masses (SRMs). Focal ablation therapy has an established role in the modern management of SRMs, especially in elderly patients and those with comorbidities. Percutaneous ablation avoids general anaesthesia and laparoscopic ablation can avoid excessive dissection; hence, these techniques can be suitable for patients who are not ideal surgical candidates. Several ablation modalities exist, of which radiofrequency ablation and cryoablation are most widely applied and for which safety and oncological efficacy approach equivalency to partial nephrectomy. Data supporting efficacy and safety of ablation techniques continue to mature, but they originate in institutional case series that are confounded by cohort heterogeneity, selection bias, and lack of long-term follow-up periods. Image guidance and surveillance protocols after ablation vary and no consensus has been established. The importance of SRM biopsy, its optimal timing, the type of biopsy used, and its role in treatment selection continue to be debated. As safety data for active surveillance and experience with minimally invasive partial nephrectomy are expanding, the role of focal ablation therapy in the treatment of patients with SRMs requires continued evaluation.

Current Role of Active Surveillance in the Management of a Small Renal Mass

Renal cell carcinoma accounts for 3-4% of adult malignant neoplasms and over 65,000 new cases of kidney cancer were diagnosed in the USA in 2013 [1, 2]. Widespread use of abdominal imaging is leading to an increased incidence in the detection of small renal masses (SRMs) among other causes [1-4]. In light of recent literature on the role of percutaneous renal mass biopsy and retrospective data analysis, surveillance for renal masses ≤4 cm is likely to become more common especially in patients with less aggressive pathology, advanced age and multiple medical comorbidities.

Renal Cell Carcinoma: Alternative Nephron-Sparing Treatment Options for Small Renal Masses, a Systematic Review

BACKGROUND

The standard treatment of T1 renal cell carcinoma (RCC) is (partial) nephrectomy. For patients where surgery is not the treatment of choice, for example in the elderly, in case of severe comorbidity, inoperability, or refusal of surgery, alternative treatment options are available. These treatment options include active surveillance (AS), radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA), or stereotactic body radiotherapy (SBRT). In the present overview, the efficacy, safety, and outcome of these different options are summarized, particularly focusing on recent developments.

MATERIALS AND METHODS

Databases of MEDLINE (through PubMed), EMBASE, and the Cochrane Library were systematically searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The search was performed in December 2016, and included a search period from 2010 to 2016. The terms and synonyms used were renal cell carcinoma, active surveillance, radiofrequency ablation, microwave ablation, cryoablation and stereotactic body radiotherapy.

RESULTS

The database search identified 2806 records, in total 73 articles were included to assess the rationale and clinical evidence of alternative treatment modalities for small renal masses. The methodological quality of the included articles varied between level 2b and level 4.

CONCLUSION

Alternative treatment modalities, such as AS, RFA, CA, MWA, and SBRT, are treatment options especially for those patients who are unfit to undergo an invasive treatment. There are no randomized controlled trials available comparing surgery and less invasive modalities, leading to a low quality on the reported articles. A case-controlled registry might be an alternative to compare outcomes of noninvasive treatment modalities in the future.

Delayed Intervention of Small Renal Masses on Active Surveillance

Although surgical excision is the standard of therapy for small renal masses (SRMs), there is a growing recognition of active surveillance as an option in select patients who are poor surgical candidates or who have shorter life expectancy. A number of patients on expectant management, however, subsequently advance to definitive therapy. In this study, we systematically reviewed the literature and performed a pooled analysis of active surveillance series to evaluate the rate and indications for definitive treatment after initiating a period of active surveillance. Fourteen clinical series (1245 patients; 1364 lesions) met our selection criteria. Mean lesion size at presentation was 2.30 ± 0.40 cm with a mean follow-up of 33.6 ± 16.9 months. Collectively, 34.0% of patients underwent delayed intervention, which ranged in individual series from 3.6% to 70.3%. Of patients undergoing delayed intervention, the average time on active surveillance prior to definitive treatment was 27.8 ± 10.6 months. A pooled analysis revealed that 41.0% of patients underwent therapy secondary to tumor growth rate and 51.9% secondary to patient or physician preference in the absence of clinical progression. Overall, 1.1% of all patients progressed to metastatic disease during the average follow-up period. Thus, active surveillance may be an appropriate option for carefully selected patients with SRMs. However, delayed treatment is pursued in a significant percentage of patients within 3 years. Prospective registries and clinical trials with standardized indications for delayed intervention are needed to establish true rates of disease progressions and recommendations for delayed intervention.

Active Surveillance for Small Renal Masses: When Less is More

CONTEXT

A marked increase in incidentally detected small renal masses (SRMs) has occurred over the past decade. Active surveillance (AS) has emerged as an initial management option for these patients.

OBJECTIVE

(1) To determine selection criteria, assess appropriate imaging modalities and surveillance frequencies, and define triggers for delayed intervention (DI) for patients on AS. (2) To describe oncologic outcomes for patients on AS protocols.

EVIDENCE ACQUISITION

The PubMed database was queried for English language articles using the keywords "surveillance" and "renal mass" or "renal cell carcinoma" or "kidney cancer." The level of evidence, sample size, study design, and relevance to the review were considered as inclusion criteria.

EVIDENCE SYNTHESIS

A total of 69 manuscripts were included in the review. Selection criteria at initial evaluation for patients interested in AS include patient-related factors (eg, age, baseline renal function, other comorbidities), tumor-related factors (size, complexity, history of growth, possible renal mass biopsy), and patient preferences (illness uncertainty, quality of life). Cross-sectional imaging is the preferred initial imaging modality. Surveillance imaging should be performed at frequent intervals (3-4 mo) up front; intervals can be reduced over time if favorable growth kinetics are demonstrated. Delayed intervention (DI) should be considered for rapid tumor growth (eg,>0.5cm/yr), an increase in maximum tumor diameter >3-4cm, malignant renal mass biopsy results, development of symptoms, or patient preferences. Oncologic outcomes in well-controlled studies demonstrate a metastatic rate of 1-2%. Most patients who undergo DI remain eligible for nephron-sparing approaches; oncologic outcomes are not compromised by DI strategies.

CONCLUSIONS

A period of initial AS is safe for most patients with SRMs. Management decisions should focus on a thorough assessment of risk-benefit trade-offs, judiciously integrating patient-related factors, tumor-related factors, and patient preferences.

PATIENT SUMMARY

A period of initial active surveillance for kidney masses of ≤4cm in diameter is safe in most patients. Frequent imaging and follow-up are necessary to determine if the tumor grows. If delayed intervention becomes necessary, cancer outcomes are not compromised by the initial choice of active surveillance when patients adhere to close follow-up regimens.

Imaging of Solid Renal Masses

Detection of solid renal masses has increased, although it has not resulted in significant mortality reduction from renal cell carcinoma. Efforts for improved lesion characterization have been pursued and incorporated in management algorithms, in order to distinguish clinically significant tumors from favorable or benign conditions. Concurrently, imaging methods have produced evidence supporting their role as useful tools not only in lesion detection but also characterization. In addition, newer modalities, such as contrast-enhanced ultrasonography, and advanced applications of MR imaging, are being investigated. This article reviews the current role of different imaging methods in the characterization of solid renal masses.

Predictors of Delayed Intervention for Patients on Active Surveillance for Small Renal Masses: Does Renal Mass Biopsy Influence Our Decision?

OBJECTIVE

To review our clinical T1a renal mass active surveillance (AS) cohort to determine whether renal mass biopsy was associated with maintenance of AS.

MATERIALS AND METHODS

From our prospectively maintained database we identified patients starting AS from June 2009 to December 2011 who had at least 5 months of radiologic follow-up, unless limited by unexpected death or delayed intervention. The primary outcome was delayed intervention. Clinical, radiologic, and pathologic variables were compared. We constructed Kaplan-Meier survival curves for maintenance of AS. Cox multivariable regression analysis was performed to assess predictors of delayed intervention.

RESULTS

We identified 118 patients who met criteria for inclusion with a median radiologic follow-up of 29.5 months. The delayed intervention group had greater initial mass size and faster growth rate compared to those who continued AS. Rate of renal mass biopsy was similar between the 2 groups. In the multivariable analysis, size >2 cm (hazard ratio [HR] 3.65, 95% confidence interval [CI] 1.28-10.38, P = .015), growth rate (continuous by mm/year: HR 1.26, 95% CI 1.12-1.41, P < .001), but not renal biopsy (HR 1.52, 95% CI 0.70-3.30, P = .29), were associated with increased risk of delayed intervention. Time-to-event curves also showed that size was closely associated with delayed intervention whereas renal mass biopsy was not.

CONCLUSION

At our institution, growth rate and initial tumor size appear to be more influential than renal mass biopsy results in determining delayed intervention after a period of AS. Further analysis is required to determine the role of renal biopsy in the management of patients being considered for AS.

Surveillance of Small Renal Masses

The widespread utilization of imaging has led to an increasing incidence of small renal masses (SRMs). However, at least 20% are benign. Nevertheless, nephron-sparing surgery is the standard treatment for SRMs without pretreatment characterization with biopsy. Elderly patients and patients with multiple comorbidities and limited life expectancy may safely be managed with active surveillance with low risk of disease progression and mortality. An initial period of observation to determine tumor growth kinetics is safe and appropriate in select candidates. Renal tumor biopsy is accurate, safe and should be considered for SRMs prior to finalizing treatment plans.

Preoperative evaluation of renal cell carcinoma by using 18F-FDG PET/CT

PURPOSE

This study aimed to characterize the FDG uptake of renal cell carcinoma (RCC) by the pathological subtype and nuclear grade.

PATIENTS AND METHODS

We retrospectively identified patients who underwent F-FDG PET and subsequent partial or radical nephrectomy for renal tumors. The relationships of the SUV of renal tumor with subtypes, nuclear grade, and clinicopathological variables were investigated.

RESULTS

Ninety-two tumors were analyzed, including 52 low-grade (G1 and G2) and 18 high-grade (G3 and G4) clear cell RCC; 7 chromophobe, 5 papillary, and 1 unclassified RCC; and 9 benign tumors (7 angiomyolipoma and 2 oncocytoma). The SUVs of high-grade clear cell RCC (mean ± SD, 6.8 ± 5.1) and papillary RCC (6.6 ± 3.7) were significantly higher than that of the controls (2.2 ± 0.3). The SUV of high-grade clear cell RCC was higher than that of low-grade tumors (median, 4.0 vs. 2.2; P < 0.001). The optimal SUV cutoff value of 3.0 helped to differentiate high-grade from low-grade clear cell RCC, with 89% sensitivity and 87% specificity. On multiple regression analysis, a high grade was the most significant predictor of SUV for clear cell RCC.

CONCLUSIONS

FDG uptake higher than that observed in normal kidney tissues suggests a high-grade clear cell RCC or papillary RCC subtype. FDG-PET using SUV may have a role in prediction of pathological grade of renal tumor.

Natural history of small renal masses

Objective:

To review the natural history and growth kinetics of small renal masses (SRMs).

Data Sources:

The literature concerning natural history and growth kinetics of SRMs was collected from PubMed published from 1990 to 2014.

Study Selection:

We included all the relevant articles on the active surveillance (AS) or delayed treatment for SRMs in English, with no limitation of study design.

Results:

SRMs under AS have a slow growth potential in general. The mean linear growth rate is 0.33 cm/year, the mean volumetric growth rate is 9.48 cm³/year. The rate of metastasis during AS is below 2%. Some factors are associated with the growth rate of SRMs, including tumor grade, histological subtype, initial tumor size, age, radiographic characteristics, and molecular markers. No definite predictor of growth rate of SRMs is defined at present. SRMs with high tumor grade and the subtype of clear cell renal cell carcinoma may have aggressive growth potential.

Conclusions:

AS is a reasonable choice for elderly patients with SRMs, who are at high risk from surgery. Progression during observation is the biggest concern while performing AS. There is no definite predictor of progression for SRMs under AS. Percutaneous renal biopsy providing immunohistological and genic biomarkers may improve the understanding of natural history of SRMs.

Active surveillance in prostate cancer: a concept analysis

AIM

To report an analysis of the concept of active surveillance.

BACKGROUND

Prostate cancer has become more prevalent since the introduction of PSA screening, however, many men are diagnosed with low-risk disease that may not require treatment. Active surveillance is a treatment strategy used to avoid treatment and related adverse effects when immediate treatment is not necessary. A universal definition is lacking.

DESIGN

Concept analysis.

DATA SOURCES

The CINAHL, PubMed, Scopus, Cochrane Library and Google Scholar databases were searched for literature published between 1980 and 2014 using the term active surveillance.

METHODS

The method of Walker and Avant (2010) was used to analyse the concept of active surveillance, specifically within the context of prostate cancer.

RESULTS

Key attributes of active surveillance emerging from the analysis include: regular and purposeful monitoring, early detection of disease progression and planned curative intervention if necessary. Multiple terms are used in the literature to refer to the concept of active surveillance. Active surveillance can cause uncertainty, and prompt men to make lifestyle changes and seek more information on prostate cancer.

CONCLUSION

Active surveillance is not well understood, and ambiguity remains around the concept. Active surveillance and watchful waiting are used interchangeably in the literature and in clinical practice, but in fact do not refer to the same strategy. Active surveillance can generate significant uncertainty for the patient and family, which may be a barrier to choosing it as a treatment strategy and nursing research in this area is limited.

RELEVANCE TO CLINICAL PRACTICE

Nurses need a clear understanding of active surveillance and how it differs from other strategies in order to reduce ambiguity around the concept. Nurses must be aware of the uncertainty accompanying active surveillance, and a need exists for continued nursing research in this area.

Population-based assessment of cancer-specific mortality after local tumour ablation or observation for kidney cancer: a competing risks analysis

OBJECTIVES

To examine, using competing risks regression, differences in cancer-specific mortality (CSM) that might distinguish between local tumour ablation (LTA) and observation (OBS) for patients with kidney cancer.

PATIENTS AND METHODS

The study focused on 1 860 patients with cT1a kidney cancer treated with either LTA or OBS between 2000 and 2009 in the Surveillance Epidemiology and End Results-Medicare database. Propensity-score matching was used. The study outcome was CSM. Multivariable competing risks regression analyses, adjusting for other-cause mortality as well as patient (including comorbidities) and tumour characteristics, were fitted.

RESULTS

Overall, fewer patients underwent LTA than OBS (30 vs 70%; n = 553 vs n = 1 307). Compared with patients in the OBS group, those in the LTA group were younger (median age 77 vs 78 years; P < 0.001), more likely to be white (84 vs 78%; P = 0.005), more frequently married (59 vs 52%; P = 0.02) and more frequently of high socio-economic status (54 vs 45%; P = 0.001). After propensity-score matching, 553 patients who underwent LTA and 553 who underwent OBS remained for subsequent analyses. The mean standardized differences of patient characteristics between the two groups were <10%, indicating a high degree of similarity. After LTA or OBS, the 5-year CSM estimates from Poisson regression-derived smoothed plots were 3.5 and 9.1%, respectively. In multivariable competing risks regression analyses, LTA use was found to have a protective effect on CSM (hazard ratio 0.47 [95% confidence interval 0.25-0.89]; P = 0.02).

CONCLUSIONS

After adjustment for comorbidity and tumour characteristics in elderly patients with kidney cancer, LTA was associated with a clinically and statistically significant protective effect on CSM, compared with OBS. This advantage of LTA deserves consideration when obtaining informed consent.

Growth Pattern of Clear Cell Renal Cell Carcinoma in Patients with Delayed Surgical Intervention: Fast Growth Rate Correlates with High Grade and May Result in Poor Prognosis

Objectives. Previous studies revealed an unclear correlation between the growth rate of renal cell carcinoma (RCC) and tumor grade and did not focus on certain histological subtype. This report investigated the correlation between the growth rate and tumor grade in clear cell RCC (ccRCC). Methods. We reviewed 60 patients with 61 ccRCC confirmed by delayed surgeries after at least 12 months of active surveillance. The linear growth rate (LGR), volumetric growth rate (VGR), and volume doubling time (VDT) were calculated, and their correlations with clinicopathologic characteristics were analyzed. Results. The mean LGR, VGR, and VDT were 0.86 (range 0–4.74) cm/year, 20.96 (range 0.31–211.93) cm³/year, and 667 (range 33–3321) days, respectively. ccRCCs with high grade had greater LGR (P < 0.001) and VGR (P = 0.001) and lower VDT (P = 0.017) than ccRCCs with low grade. Grade (OR = 5.185, P = 0.004) was the only independent risk factor of LGR >0.5 cm/year, and grade (OR = 3.006, P = 0.046) and initial size (OR = 0.392, P = 0.004) were independent risk factors of VDT <1 year. Five patients developed metastasis after surgery with LGR >0.5 cm/yr altogether; of them, four had cancer-related death by the last follow-up. Conclusions. Fast growth rate of ccRCC is significantly correlated with high tumor grade and may result in poor prognosis, especially for those with LGR >0.5 cm/yr.

The management of small renal masses: what is likely to change?

The diffusion of imaging has determined an increased discovery of small renal masses (SRMs). Recent publications have been reviewed to present the state of the art in the management of SRMs and to try to foresee the next steps in this challenging condition. The role of percutaneous biopsies is expanding, since management algorithms include also active surveillance and ablative therapies. However up to 30% of biopsies fail to provide histological diagnosis and there is the risk of under-evaluating high-grade tumors. Active surveillance has been proposed in patients with reduced life expectancy and numerous comorbidities. The average growth of SRMs is slow, and metastatic progression has been observed in about 1%. Ablative therapies (cryotherapy and radiofrequency ablation) are used in patients with relevant comorbidities or advanced age and unfit for surgery, but who desire active treatment. Compared to conservative surgical treatment both techniques have increased local progression rates, while metastatic progression is relatively low.Partial nephrectomy (PN) is the recommended curative treatment for SRMs and can be performed open, laparoscopically or robotically. Open PN represents the benchmark, with similar cancer specific survival and better preservation of renal function compared to nephrectomy. Laparoscopy is comparable to open surgery in terms of oncologic results, but a long learning curve is necessary. Perioperative outcomes of robot-assisted PN appear superior to laparoscopy and the learning curve is shorter, but data for oncological results are still immature. With the increasing diffusion of robotic technology it is likely more SRMs will be managed with this approach.

Efficacy of percutaneous cryoablation of renal cell carcinoma in older patients with medical comorbidities: Outcome study in 70 patients

INTRODUCTION

The aim of this study was to establish the efficacy of cryoablation for incidentally discovered small renal cell carcinomas in older patients with medical comorbidities.

METHODS

We carried out a retrospective chart analysis of outcomes of 70 patients treated by cryoablation. The inclusion criteria were age >56 years, medical comorbidities (Charlson class I-III), and suitability for cryoablation established by urologists and interventional radiologists. In total, 43 patients were male, 27 female, and the age range was 56 to 89. The lesions measured 1.5 to 4 cm; 29 were high-grade Fuhrman and 41 were low grade. All lesions were treated by 2 10-minute freezing cycles separated by an 8-minute thawing period. One to seven cryoprobes were inserted according to a preoperative, 3D computed tomography (CT)-based plan.

RESULTS

Results were assessed on follow-up CTs (at 8-9 months). Of the 70 patients, 68 were treated by cryoablations and surgical salvage procedures; these patients were free of disease for 23 to 72 months (mean 39). One patient experienced recurrence and the other was lost to follow-up. One or two cryoablations rendered 66 patients tumour-free and additional surgery rendered another 2 patients tumour-free. The location and configuration of the lesion affected outcomes. Of the 27 posterior lesions, there was 1 failure; of the postero-lateral lesions, there were 4 failures; of the anterior lesions, there were 5 lesions; finally of the 32 central or deep seated lesions, there were 9 failures. Implants with one and two cryoprobes had a high recurrence rate. Three major complications were managed by minor interventions. The mean hospitalization was 1.3 days and the procedure times were variable.

CONCLUSION

Percutaneous cryoablation is recommended as a minimally invasive nephron-sparing treatment for amenable lesions in older patients with medical comorbidities.

Imaging management of incidentally detected small renal masses

Both imaging and intervention play an increasingly important role in the management of renal masses in general and renal cancer in particular. Indeed, radiologists are often the first to detect and diagnose renal cancer, and now with the burgeoning role of percutaneous ablation, they are often the treating physicians. Renal mass management begins with imaging, and although most can be diagnosed with a high degree of certainty using imaging, some remain indeterminate and require biopsy or observation, now referred to as active surveillance. Although active surveillance strategies have been employed for indeterminate renal masses that have a reasonable chance of being benign, recent data suggest that some renal cancers can undergo active surveillance safely. This article reviews the current imaging-based diagnostic evaluation of incidentally detected small renal masses, the burgeoning role of percutaneous biopsy, and how both imaging and biopsy are used to help select which patients need treatment and which can undergo active surveillance.

Active surveillance for renal angiomyolipoma: outcomes and factors predictive of delayed intervention

OBJECTIVE

To present the outcomes of active surveillance (AS) for renal angiomyolipomas (AMLs) and to assess the clinical features predicting delayed intervention of this treatment option.

PATIENTS AND METHODS

We retrospectively reviewed the outcomes of patients diagnosed with AMLs on computed tomography (CT) who were managed with AS at our institution. The AS protocol consisted of 6- and 12-month, then annual follow-up visits, each one including a physical examination and CT imaging. Discontinuation of AS was defined as the need or decision for an active procedure during the follow-up period. Causes of delayed intervention, as well as the type of active treatment (AT), were recorded. Clinical features at presentation of patients failing AS were compared with those who remained under AS at the time of the last follow-up. Predictive factors of delayed intervention were analysed using univariate and multivariate Cox regression models.

RESULTS

Overall, 130 patients were included in the analysis, of whom 102 (78.5%) were incidentally diagnosed, while 15 (11.5%) and 13 patients (10%) presented with flank pain and haematuria, respectively. After a mean (sd) follow-up of 49 (40) months, 17 patients (13%) discontinued AS and underwent AT. Patients who underwent delayed intervention were more likely to present with a higher body mass index, larger tumours and symptomatic disease. Angioembolization represented the first-line AT after AS (64.7%), whereas partial nephrectomy was adopted in 29.4% of patients. On the univariate analysis, risk factors for delayed intervention included tumour size ≥4 cm, symptoms at diagnosis, and history of concomitant or contralateral kidney disease. On the multivariate analysis, only tumour size and symptoms remained independently associated with discontinuation of AS.

CONCLUSIONS

Tumour size and symptoms at initial presentation were highly predictive of discontinuation of AS in the management of AMLs. Selective angioembolization was the first-line option used for AT after AS was discontinued.

RENAL nephrometry score is a predictive factor for the annual growth rate of renal mass

OBJECTIVE

To evaluate the association between the RENAL nephrometry score and annual growth rates of renal masses presumed to be renal cell carcinoma.

METHODS

The current study included 47 renal tumors followed up for at least 12 months, of which 26 tumors were found to be pathologically proven renal cell carcinomas. Annual tumor growth rates were calculated from changes in the maximal diameter on computed tomography, and RENAL nephrometry scores were recorded on initial imaging by two senior urologists. The associations between clinical characteristics including the RENAL nephrometry score and annual growth rates were analyzed using a linear regression model.

RESULTS

The median tumor size at diagnosis was 1.7 cm (range 0.6-5.8). The median nephrometry score at diagnosis was 7 (range 4-10). Overall, the median tumor growth rate was 0.34 cm per year (range -0.19-2.0). Linear regression analysis showed that the annual tumor growth rate was associated with the RENAL nephrometry score (P < 0.0001), but it was independent of the age at diagnosis, sex and initial tumor size. In addition, the correlation between the RENAL nephrometry score and annual growth rate remained significant in the 26 pathologically proven renal cell carcinomas.

CONCLUSIONS

The RENAL nephrometry score is associated with the annual growth rate of renal masses. Our findings further support the association between the RENAL nephrometry score and tumor biology.

Active surveillance for small renal masses diagnosed in elderly or comorbid patients: looking for the best treatment strategy

INTRODUCTION

Aim of this study is to provide our results after long-term active surveillance (AS) protocol for small renal masses (SRMs), and to report the outcomes of patients who remained in AS compared to those who underwent delayed surgical intervention.

PATIENTS AND METHODS

We retrospectively reviewed our database of 58 patients diagnosed with 60 contrast enhancing SRMs suspicious for renal cell carcinoma (RCC). All patients had clinical and radiological follow-up every 6 months. We evaluated the differences between patients who remained on AS and those who underwent surgical delayed intervention.

RESULTS

The mean age was 75 years, the mean follow-up was 88.5 months. The median initial tumor size at presentation was 2.6cm, and the median estimated tumor volume was 8.7cm(3). The median linear growth rate of the cohort was 0.7cm/year, and the median volumetric growth rate was 8.8 cm(3)/year. Death for metastatic disease occurred in 2 patients (3.4%). No correlation was found between initial tumor size and size growth rate. The mean linear and volumetric growth rates of the group of patients who underwent surgery was higher than in those who remained on surveillance (1.9 vs. 0.4cm/year and 16.1 vs. 4.6 cm(3)/year, respectively; P<.001).

CONCLUSIONS

Most of SRMs demonstrate to have an indolent course and low metastatic potential. Malignant disease could have faster linear and volumetric growth rates, thus suggesting the need for a delayed surgical intervention. In properly selected patients with low life-expectancy, AS could be a reasonable option in the management of SRMs.