Delayed intervention of sporadic renal masses undergoing active surveillance

Role of Contrast-Enhanced Ultrasound in Evaluation of Cystic Renal Mass

OBJECTIVES

Contrast-enhanced ultrasound (CEUS) allows excellent delineation of perfusion in septa and nodules without exposure to ionizing radiation or nephrotoxic contrast media. The aim of our study was to evaluate the role of CEUS for the assessment of cystic renal masses and compare its diagnostic performance with that of CECT.

METHODS

Exactly 40 patients diagnosed to have cystic renal masses on CECT scan were prospectively evaluated with CEUS and were assigned a Bosniak class. Based on results of final histopathology and clinical follow-up, internal validity of both CEUS and CECT was evaluated, including agreement between these two modalities.

RESULTS

Out of the 40 patients (mean size 3.1 ± 2.5 cm), 23 patients had benign lesions and 17 patients had malignant lesions. For CEUS, the sensitivity and negative predictive value was 100%, the specificity and positive predictive value was 73.9%. For CECT, the sensitivity and negative predictive value were 88.2 and 83.3%, respectively, whereas the specificity and positive predictive value was 87 and 90.9%, respectively. Both imaging modalities had similar accuracy with fair to good agreement with the final diagnosis (Κ = 0.71 and 0.75 for CEUS and CECT, respectively). Concordance between CEUS and CECT was seen in 29 patients (72.5%) with fair agreement between the two modalities (K = 0.66).

CONCLUSION

CEUS has comparable accuracy with CECT and could be used as screening modality to rule out the presence of complex cystic renal masses without exposure of nephrotoxic contrast media and ionizing radiation.

"Could Patient Age and Gender, along with Mass Size, Be Predictive Factors for Benign Kidney Tumors?": A Retrospective Analysis of 307 Consecutive Single Renal Masses Treated with Partial or Radical Nephrectomy

Due to the increased use of common and non-invasive abdominal imaging techniques over the last few decades, the diagnosis of about 60% of renal tumors is incidental. Contrast-enhancing renal nodules on computed tomography are diagnosed as malignant tumors, which are often removed surgically without first performing a biopsy. Most kidney nodules are renal cell carcinoma (RCC) after surgical treatment, but a non-negligible rate of these nodules may be benign on final pathology; as a result, patients undergo unnecessary surgery with an associated significant morbidity. Our study aimed to identify a subgroup of patients with higher odds of harboring benign tumors, who would hence benefit from further diagnostic examinations (such as renal biopsy) or active surveillance. We performed a retrospective review of the medical data, including pathology results, of patients undergoing surgery for solid renal masses that were suspected to be RCCs (for a total sample of 307 patients). Owing to the widespread use of common and non-invasive imaging techniques, the incidental diagnosis of kidney tumors has become increasingly common. Considering that a non-negligible rate of these tumors is found to be benign after surgery at pathological examination, it is crucial to identify features that can correctly diagnose a mass as benign or not. According to our study results, female sex and tumor size ≤ 3 cm were independent predictors of benign disease. Contrary to that demonstrated by other authors, increasing patient age was also positively linked to a greater risk of malign pathology.

Impact of Time-To-Surgery on the Prognosis of Patients with T1 Renal Cell Carcinoma: Implications for the COVID-19 Pandemic

Background: During the COVID-19 pandemic, elective surgery has to undergo longer wait times, including nephrectomy for T1 renal cell carcinoma (RCC). This study aimed to investigate the time-to-surgery (TTS) of Chinese T1 RCC patients and its influencing factors, and to illustrate the impact of TTS on the prognosis of T1 RCC. Methods: We retrospectively enrolled 762 Chinese patients with pathological T1 RCC that underwent nephrectomy. To discover the impact of TTS on survival outcomes, we explored the possible delay intervals by week using the Kaplan-Meier method and Log-rank test. Cox proportional hazard models with inverse probability-treatment weighting (IPTW) were used to assess the association between TTS and disease-free survival (DFS) and overall survival (OS). Results: The median TTS of T1 RCC patients was 15 days. The Charlson comorbidity index, the Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) score, and the maximal tumor diameter on presentation were independent influencing factors for TTS. The cut-off point of TTS was selected as 5 weeks according to the Log-rank analysis. For T1a RCC, patients with TTS > 5 weeks had similar DFS (HR = 2.39; 95% CI, 0.82−6.94; p = 0.109) and OS (HR = 1.28; 95% CI, 0.23−7.16; p = 0.779) compared to patients with TTS ≤ 5 weeks. For T1b RCC, patients with TTS > 5 weeks had shorter DFS (HR = 2.90; 95% CI = 1.46−5.75; p = 0.002) and OS (HR = 2.49, 95% CI = 1.09−5.70; p = 0.030) than patients with TTS ≤ 5 weeks. Conclusions: Prolonged TTS had no impact on the prognosis of T1a RCC while surgery delayed for over 5 weeks may lead to worse survival in T1b RCC.

The impact of tumor size on the survival of patients with small renal masses: A population-based study

Background

Active surveillance (AS) with delayed intervention has gained acceptance as a management strategy for small renal masses (SRMs). However, during AS, there is a risk of tumor growth. Thus, we aim to investigate whether tumor growth in patients with SRMs leads to tumor progress.

Methods

In this study, we enrolled 16,070 patients from the Surveillance, Epidemiology, and End Results database with T1a renal cell carcinoma (RCC) between 2004 and 2017. The 16,070 patients were divided into three groups: 10,526 in the partial nephrectomy (PN) group, 2768 in the local ablation (LA) group, and 2776 in the AS group. Associations of tumor size with all‐cause and cancer‐specific mortality were evaluated using Kaplan–Meier analyses and Cox regression models.

Results

Four tumor size categories were delineated (≤1, >1–2, >2–3, and > 3–4 cm in diameter), and 10‐year all‐cause and cancer‐specific mortality both significantly increased with increasing tumor size in the PN, LA, and AS groups (all p < 0.05). Tumors were substaged based on diameter: T1aA (≤2 cm) and T1aB (>2–4 cm). All‐cause and cancer‐specific mortality were significantly higher in T1aB tumors than T1aA tumors in each group (hazard ratio = 1.395 and 1.538, respectively; all p < 0.05).

Conclusions

Tumor growth relates to worse prognosis of T1a RCC, and 2 cm serves as a size threshold that is prognostically relevant for patients with T1a RCC. Because of the lack of accurate predictors of tumor growth rate, AS for patients with SRMs incurs a risk of tumor progression.

Nephrectomy Delay of More than 10 Weeks from Diagnosis Is Associated with Decreased Overall Survival in pT3 RCC

In this study, we aimed to evaluate the impact of surgical wait time (SWT) on outcomes of patients with renal cell carcinoma (RCC), and to investigate risk factors associated with prolonged SWT. Using the National Cancer Database, we retrospectively reviewed the records of patients with pT3 RCC treated with radical or partial nephrectomy between 2004 and 2014. The cohort was divided based on SWT. The primary outcome was 5-year overall survival (OS). Logistic regression analysis was used to investigate the risk factors associated with delayed surgery. Cox proportional hazards models were fitted to assess relations between SWT and 5-year OS after adjusting for confounding factors. A total of 22,653 patients were included in the analysis. Patients with SWT > 10 weeks had higher occurrence of upstaging. Using logistic regression, we found that female patients, African-American or Spanish origin patients, treatment in academic or integrated network cancer center, lack of insurance, median household income of <$38,000, and the Charlson-Deyo score of ≥1 were more likely to have prolonged SWT. SWT > 10 weeks was associated with decreased 5-year OS (hazard ratio [HR], 1.24; 95% confidence interval [CI], 1.15-1.33). This risk was not markedly attenuated after adjusting for confounding variables, including age, gender, race, insurance status, Charlson-Deyo score, tumor size, and surgical margin status (adjusted HR, 1.13; 95% CI, 1.04-1.24). In conclusion, the vast majority of patients underwent surgery within 10 weeks. There is a statistically significant trend of increasing SWT over the study period. SWT > 10 weeks is associated with decreased 5-year OS.

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.

Association of Surgical Delay and Overall Survival in Patients With T2 Renal Masses: Implications for Critical Clinical Decision-making During the COVID-19 Pandemic

OBJECTIVE

To test for an association between surgical delay and overall survival (OS) for patients with T2 renal masses. Many health care systems are balancing resources to manage the current COVID-19 pandemic, which may result in surgical delay for patients with large renal masses.

METHODS

Using Cox proportional hazard models, we analyzed data from the National Cancer Database for patients undergoing extirpative surgery for clinical T2N0M0 renal masses between 2004 and 2015. Study outcomes were to assess for an association between surgical delay with OS and pathologic stage.

RESULTS

We identified 11,848 patients who underwent extirpative surgery for clinical T2 renal masses. Compared with patients undergoing surgery within 2 months of diagnosis, we found worse OS for patients with a surgical delay of 3-4 months (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.00-1.25) or 5-6 months (HR 1.51, 95% CI 1.19-1.91). Considering only healthy patients with Charlson Comorbidity Index = 0, worse OS was associated with surgical delay of 5-6 months (HR 1.68, 95% CI 1.21-2.34, P= .002) but not 3-4 months (HR 1.08, 95% CI 0.93-1.26, P = 309). Pathologic stage (pT or pN) was not associated with surgical delay.

CONCLUSION

Prolonged surgical delay (5-6 months) for patients with T2 renal tumors appears to have a negative impact on OS while shorter surgical delay (3-4 months) was not associated with worse OS in healthy patients. The data presented in this study may help patients and providers to weigh the risk of surgical delay versus the risk of iatrogenic SARS-CoV-2 exposure during resurgent waves of the COVID-19 pandemic.

Renal tumor growth rate in patients with previously normal CT scan: Analysis of the initial stage of growth

OBJECTIVE

Most of the studies regarding natural history of renal masses are based on active surveillance series and suggest that the renal masses have a slow growth rate. Nevertheless, only a few studies report the time between a normal computed tomography (CT) scan to the first detection of a tumor. We aimed to analyze the growth rate in newly diagnosed kidney tumors.

MATERIAL AND METHODS

We analyzed patients with enhancing renal masses that developed after a normal CT scan, which was performed at most 12 months earlier. Variables examined included patient age, gender, tumor size, volume, tumor linear growth rate (LGR). All cases were surgically treated. Mann-Whitney U test was used to compare variables. A p<0.05 was considered as statistically significant.

RESULTS

We found 31 patients with 33 lesions. Male to female ratio was 1.58 (19/12). The average age was 59.2 years (standard deviation [SD]±12.1), and the mean tumor size was 4.27 cm (SD±4.3). Tumor LGR was 0.87 cm/month (range: 0.28-1.66) and presumed to be 10.4 cm at 1 year (range: 3.36-19.9). Tumor LGR for time detection at <6 month or ≥6 months were 1.1 cm/month and 0.68 cm/month (range: 0.27-1.08 and 0.88-1.76, respectively; p=0.0004), respectively. Tumor LGRs for low- and high-grade tumors were 0.89 cm/month and 0.83 cm/month (p=0.65), respectively. Median volume was 36.1 cm³ (range: 2.61-143.7), and for low and high grade the median volumes were 27.9 cm³ and 47.6 cm³, respectively (p=0.54). Malignant pathology was present in 93.9 % (31 of 33) of masses (lesions).

CONCLUSION

We found differences in tumor LGR in tumors detected before and after 6 months. We did not find any correlation between tumor growth rate and Fuhrman grade system, gender, histology, or age. We found the highest LGR published up to date.

Active surveillance of small renal masses

Most renal masses incidentally detected by cross-sectional images are benign, being mainly cysts, and if they are malignant, they are indolent in nature with limited metastatic potential. Enhanced renal masses less than 4 cm in size are known as small renal masses (SRMs), and their growth rate (GR) and the possibility of developing metastasis are extremely low. Delayed intervention of SRMs by closed and routine imaging follow-up known as active surveillance (AS) is now an option according to urological guidelines. Radiologists have a key position in AS management of SRMs even unifocal and multifocal (sporadic or associated with genetic syndromes) and also in the follow-up of complex renal cysts by Bosniak cyst classification system. Radiologists play a key role in the AS of both unifocal and multifocal (sporadic or associated with genetic syndromes) SRMs as well as in the follow-up of complex renal cysts using the Bosniak cyst classification system. Indeed, radiologists must determine which patients with SRMs or complex renal cysts can be included in AS, establish the follow-up radiological test algorithm to be used in different scenarios, perform measurements in follow-up tests, and decide when AS should be discontinued. The purpose of this article is to review the indications and management of AS in SRMs, especially focused on specific scenarios, such as complex renal cysts and multifocal renal tumors (sporadic or hereditary). In this work, the authors aimed to provide a thorough review of imaging in the context of active surveillance of renal masses.

Computed tomography imaging characteristics of clear cell papillary renal cell carcinoma

Purpose:

Clear cell papillary (CCP) renal cell carcinoma (RCC) is a new subtype of RCC that was formally recognized by the International Society of Urological Pathology Vancouver Classification of Renal Neoplasia in 2013. Subsequently, CCP RCC was added to the 2016 World Health Organization Classification of Tumors of the Urinary System and Male Genital Organs. In this study, we retrospectively investigated the computed tomography (CT) findings of pathologically diagnosed CCP RCC.

Materials and Methods:

This study included 12 patients pathologically diagnosed with CCP RCC at our institution between 2015 and 2017. We reviewed the patient's CT data and analyzed the characteristics.

Results:

Nine solid masses and 3 cystic masses with a mean tumor size of 22.7±9.2mm were included. Solid masses exhibited slight hyper-density on unenhanced CT with a mean value of 34±6 Hounsfield units (HU), good enhancement in the corticomedullary phase with a mean of 195±34HU, and washout in the nephrogenic phase with a mean of 133±29HU. The walls of cystic masses enhanced gradually during the corticomedullary and nephrogenic phases. Solid and cystic masses were preoperatively diagnosed as clear cell RCC and cystic RCC, respectively.

Conclusions:

The CT imaging characteristics of CCP RCCs could be categorized into either the solid or cystic type. These masses were diagnosed radiologically as clear cell RCC and cystic RCC, respectively.

Delayed nephrectomy has comparable long-term overall survival to immediate nephrectomy for cT1a renal cell carcinoma: A population-based analysis

OBJECTIVES

Early surgical resection remains the recommended treatment option for most small renal mass (≤4 cm). We examined the long-term overall survival (OS) of patients managed with delayed and immediate nephrectomy of cT1a renal cancer.

PATIENT AND METHODS

We utilized the National Cancer Database (2005-2010) to identify 14,677 patients (immediate nephrectomy: 14,050 patients vs. late nephrectomy: 627 patients) aged <70 years with Charlson Comorbidity Index 0 and cT1aN0M0 renal cell carcinoma. Immediate nephrectomy and late nephrectomy were defined as nephrectomy performed <30 days and >180 days from diagnosis, respectively. Inverse probability of treatment weighting-adjusted Kaplan-Meier curves and Cox proportional hazards regression analyses were used to compare OS of patients in the 2 treatment arms. Influence of patient age and Charlson Comorbidity Index on treatment effect was tested by interactions. Sensitivity analysis was performed to explore the outcome of delaying nephrectomy for >12 months.

RESULTS

Median patient age was 55 years with a median follow-up of 82.5 months. Inverse probability of treatment weighting-adjusted Kaplan-Meier curves suggest no significant difference between treatment arms (immediate nephrectomy [<30 days] vs. delayed nephrectomy [>180 days]) (Hazard ratio 0.96; 95% confidence interval 0.73-1.26; P = 0.77). This outcome was consistent between all patients regardless of age (P = 0.48). Sensitivity analysis reports no difference in OS even if nephrectomy was delayed by >12 months (P = 0.60).

CONCLUSIONS

We report that delayed and immediate nephrectomy for cT1a renal cell carcinoma confers comparable long-term OS. These findings suggest that a period of observation of between 6 and 12 months is safe to allow identification of renal masses, which will benefit from surgical resection.

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.

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.

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.

Oncologic Outcomes of Partial Nephrectomy for Stage T3a Renal Cell Cancer

BACKGROUND

Partial nephrectomy (PN) for clinical stage T3 tumors is controversial. Radical nephrectomy (RN) has been associated with a greater rate of chronic kidney disease, an increased risk of cardiovascular disease, and increased mortality compared with PN. We present our long-term 2-center experience with PN for stage pT3a tumors and compare the oncologic outcomes with those of similar patients treated with RN.

MATERIALS AND METHODS

We reviewed the data from all patients who had undergone nephrectomy for renal cell carcinoma from 1987 to 2015 in 2 medical centers. The study included 134 patients with pathologic stage T3a tumors, of whom 48 and 86 underwent PN and RN, respectively. We compared the 2 groups (PN and RN) using univariate and multivariate analyses.

RESULTS

The tumors of all patients with pathologic stage T3a who had undergone PN had been pathologically upstaged from clinical stage T1 or T2. Univariate and multivariate analyses revealed tumor size was significantly different statistically between the study groups (median, 7.0 cm in RN group vs. 4.0 cm in PN group; P < .001). Surgery type was not a predictor of local recurrence (P = .978), metastatic progression (P = .972), death from renal cancer (P = .626), or death from all causes (P = .974) at the 5-year follow-up point.

CONCLUSION

The results of the present study have shown similar oncologic outcomes between 48 patients with stage pT3a renal cancer who underwent PN and 86 patients who underwent RN. Although PN was not performed on clinical T3a tumors, our findings suggest that PN can also be considered for these tumors and, thus, avoid the long-term complications of RN. However, strict follow-up protocols are mandatory.

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.

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.

Active Surveillance for the Small Renal Mass: Growth Kinetics and Oncologic Outcomes

Active surveillance for small renal masses (SRMs) is an accepted management strategy for patients with prohibitive surgical risk. Emerging prospectively collected data support the concept that a period of initial active surveillance in an adherent patient population with well-defined criteria for delayed intervention is safe. This article summarizes the literature describing growth kinetics of SRMs managed initially with observation and oncologic outcomes for patients managed with active surveillance. Existing clinical tools to determine and contextualize competing risks to mortality are explored. Finally, current prospective clinical trials with defined eligibility criteria, surveillance schema, and triggers for delayed intervention are highlighted.

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.

The role of active surveillance of small renal masses

INTRODUCTION

The use of modern abdominal imaging modalities have led in recent years to an increased incidental diagnosis of small renal masses (SRMs), especially in elderly patients. The natural history of SRMs has been historically poorly understood because most have been traditionally surgically removed soon after diagnosis. However, several studies of active surveillance (AS) of SRMs have been published in the last decade.

METHODS

A review of English-language publications on AS of SRMs was performed from 1995 to 2015 using the Medline, Embase and Web of Science databases. Fifty-six articles were selected based on their scientific relevance and critically analysed.

RESULTS

When followed conservatively with serial imaging, SRMs have variable growth rates with an average of 0.31 cm/year in the largest multicenter analysis. A significant number of SRMs have a slow growth and some have zero growth under surveillance. The risk of progression to metastatic disease during AS is rare (1-2%). Population-based analyses in older patient populations (>75 years) fail to show a benefit in cancer-specific mortality for surgical treatment of SRMs.

DISCUSSION

The standard of care for localized renal tumors is surgery. In elderly or unfit patients with decreased life expectancy, it is reasonable to propose an initial period of AS, with delayed intervention for those tumors which exhibit a fast growth during follow-up. At present AS is not recommended in younger and fit patients and for masses >4 cm at diagnosis outside clinical trials. Percutaneous needle biopsies of renal tumors have the potential to characterize histologically SRMs at diagnosis, thereby providing useful information for the selection of the best suited patients for AS.

CONCLUSIONS

Most SRMs are benign tumors or RCCs with a relatively indolent clinical behaviour. AS can be offered to patients with SRMs and decreased life expectancy. Prospective series of AS of histologically confirmed RCCs are needed to confirm the long term safety of this conservative approach.

Renal cancer

The diagnosis and management of renal cell carcinoma have changed remarkably rapidly. Although the incidence of renal cell carcinoma has been increasing, survival has improved substantially. As incidental diagnosis of small indolent cancers has become more frequent, active surveillance, robot-assisted nephron-sparing surgical techniques, and minimally invasive procedures, such as thermal ablation, have gained popularity. Despite progression in cancer control and survival, locally advanced disease and distant metastases are still diagnosed in a notable proportion of patients. An integrated management strategy that includes surgical debulking and systemic treatment with well established targeted biological drugs has improved the care of patients. Nevertheless, uncertainties, controversies, and research questions remain. Further advances are expected from translational and clinical studies.

The effect of delaying nephrectomy on oncologic outcomes in patients with renal tumors greater than 4cm

OBJECTIVES

Delaying nephrectomy<3 months does not adversely affect treatment outcome of renal tumors. Whether surgical waiting time (SWT; time from diagnosis to surgery)>3 months affects treatment outcome for large renal masses has not been well studied. We aimed to evaluate if SWT is associated with treatment outcome of renal masses >4cm and identify patients who are more likely to experience prolonged SWT.

MATERIALS AND METHODS

Data from 1,484 patients undergoing radical or partial nephrectomy at a single institution for a nonmetastatic renal mass>4cm between 1995 and 2013 were reviewed. Patients with benign tumors and incomplete preoperative data were excluded. The association between SWT and disease upstaging at the time of surgery and recurrence at 2 and 5 years was assessed using logistic regression. Cancer-specific survival (CSS) and overall survival were assessed with landmark survival analyses and multivariable Cox proportional hazards models. All analyses were adjusted for patient and tumor characteristics.

RESULTS

Of the final cohort of 1,278 patients, 267 (21%) had SWT>3 months. Patients with larger, symptomatic tumors had shorter SWT. Median follow-up for survivors was 3.8 years (interquartile range: 1.5-7.4). On multivariable analysis, SWT was not associated with disease upstaging, recurrence, or CSS. Longer SWT was associated with decreased overall survival (hazard ratio = 1.17; 95% CI: 1.08-1.27; P = 0.0002). Sex and tumor size, histology, and presentation were associated with disease upstaging, recurrence, and CSS. The most common cause for surgical delay>3 months was evaluation and treatment of comorbidities.

CONCLUSION

Patient and tumor characteristics, rather than SWT, were associated with disease upstaging, recurrence, and CSS, and should guide the decision to delay surgery when treating nonmetastatic renal tumors>4cm.

Age, Gender and R.E.N.A.L. Nephrometry Score do not Improve the Accuracy of a Risk Stratification Algorithm Based on Biopsy and Mass Size for Assigning Surveillance versus Treatment of Renal Tumors

PURPOSE

A previously published risk stratification algorithm based on renal mass biopsy and radiographic mass size was useful to designate surveillance vs the need for immediate treatment of small renal masses. Nonetheless, there were some incorrect assignments, most notably when renal mass biopsy indicated low risk malignancy but final pathology revealed high risk malignancy. We studied other factors that might improve the accuracy of this algorithm.

MATERIALS AND METHODS

For 202 clinically localized small renal masses in a total of 200 patients with available R.E.N.A.L. (radius, exophytic/endophytic, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching main renal artery or vein and location relative to polar lines) nephrometry score, preoperative renal mass biopsy and final pathology we assessed the accuracy of management assignment (surveillance vs treatment) based on the previously published risk stratification algorithm as confirmed by final pathology. Logistic regression was used to determine whether other factors (age, gender, R.E.N.A.L. score, R.E.N.A.L. score components and nomograms based on R.E.N.A.L. score) could improve assignment.

RESULTS

Of the 202 small renal masses 53 (26%) were assigned to surveillance and 149 (74%) were assigned to treatment by the risk stratification algorithm. Of the 53 lesions assigned to surveillance 25 (47%) had benign/favorable renal mass biopsy histology while in 28 (53%) intermediate renal mass biopsy histology showed a mass size less than 2 cm. Nine of these 53 masses (17%) were incorrectly assigned to surveillance in that final pathology indicated the need for treatment (ie intermediate histology and a mass greater than 2 cm or unfavorable histology). Final pathology confirmed a correct assignment in all 149 masses assigned to treatment. None of the additional parameters assessed improved assignment with statistical significance.

CONCLUSIONS

Age, gender, R.E.N.A.L. nephrometry score, R.E.N.A.L. score components and nomograms or combinations of these factors do not improve the predictive performance of a small renal mass management risk stratification algorithm based on renal mass biopsy and radiographic mass size.

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.

Evaluation and Management of the Geriatric Urologic Oncology Patient

The geriatric population presents a unique set of challenges in urologic oncology. In addition to the known natural history of disease, providers must also consider patient factors such as functional and nutritional status, comorbidities and social support when determining the treatment plan. The development of frailty measures and biomarkers to estimate surgical risk shows promise, with several assessment tools predictive of surgical complications. Decreased dependence on chronologic age is important when assessing surgical fitness, as age cutoffs prevent appropriate treatment of many elderly patients who would benefit from surgery. Within bladder, kidney and prostate cancers, continued refinement of surgical techniques offers a broader array of options for the geriatric patient than previously available.

Five-year analysis of a multi-institutional prospective clinical trial of delayed intervention and surveillance for small renal masses: the DISSRM registry

BACKGROUND

A growing body of retrospective literature is emerging regarding active surveillance (AS) for patients with small renal masses (SRMs). There are limited prospective data evaluating the effectiveness of AS compared to primary intervention (PI).

OBJECTIVE

To determine the characteristics and clinical outcomes of patients who chose AS for management of their SRM.

DESIGN, SETTING, AND PARTICIPANTS

From 2009 to 2014, the multi-institutional Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry prospectively enrolled 497 patients with solid renal masses ≤4.0cm who chose PI or AS.

INTERVENTION

AS versus PI.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The registry was designed and powered as a noninferiority study based on historic recurrence rates for PI. Analyses were performed in an intention-to-treat manner. Primary outcomes were overall survival (OS) and cancer-specific survival (CSS).

RESULTS AND LIMITATIONS

Of the 497 patients enrolled, 274 (55%) chose PI and 223 (45%) chose AS, of whom 21 (9%) crossed over to delayed intervention. AS patients were older, had worse Eastern Cooperative Oncology Group scores, total comorbidities, and cardiovascular comorbidities, had smaller tumors, and more often had multiple and bilateral lesions. OS for PI and AS was 98% and 96% at 2 yr, and 92% and 75% at 5 yr, respectively (log rank, p=0.06). At 5 yr, CSS was 99% and 100% for PI and AS, respectively (p=0.3). AS was not predictive of OS or CSS in regression modeling with relatively short follow-up.

CONCLUSIONS

In a well-selected cohort with up to 5 yr of prospective follow-up, AS was not inferior to PI.

PATIENT SUMMARY

The current report is among the first prospective analyses of patients electing for active surveillance of a small renal mass. Discussion of active surveillance should become part of the standard discussion for management of small renal masses.

The natural history of renal functional decline in patients undergoing surveillance in the DISSRM registry

OBJECTIVE

To describe the natural history of renal function in patients on active surveillance (AS) for small renal masses (SRM) in the Delayed Intervention and Surveillance for Small Renal Masses Registry.

METHODS

Delayed Intervention and Surveillance for Small Renal Masses is a prospective, multi-institutional registry of patients with SRM (≤ 4 cm) who choose intervention or AS. Of these, 64 patients on AS had longitudinal serum creatinine (sCr) values and underwent analysis of estimated glomerular filtration rate (eGFR). eGFR was calculated using the Modification of Diet in Renal Disease formula. The Kidney Disease Outcomes Quality Initiative chronic kidney disease (CKD) classification was used to categorize patients' eGFR values.

RESULTS

Median age was 74 (range: 34-88) years at onset of AS. Overall, 9% (6/64) of patients had CKD at baseline. Median initial tumor size was 2.1cm (range: 0.8-4.0). Median Charlson comorbidity index score was 4 (range: 0-8). Median baseline sCr was 1.0mg/dl (range: 0.4-2.1) and median baseline eGFR was 70.25 (range: 24.07-165.52). After a median follow-up of 17 (range: 2-46) months, 64% of patients experienced a decrease in eGFR, with average yearly decrease in eGFR of 1.82 ml/min/1.73 m(2) (P = 0.092) and average yearly increase in sCr of 0.046 (P = 0.012). A total of 15 (24%) patients experienced an upstaging in classification of CKD.

DISCUSSION

Nearly two-thirds of patients on AS experienced a decrease in eGFR and nearly one-fourth had upstaging of CKD classification. The annual eGFR decline experienced by patients on AS minimally exceeded the annual decline of 1.49 ± 0.3 ml/min/1.73 m(2) that an individual who was 70 to 79 years of age can expect from aging alone. Further follow-up is necessary to assess this in a more definitive manner, but this trend should be considered when evaluating AS as an alternative to interventional therapies for SRM.

Contemporary incidence and mortality rates of kidney cancer in the United States

INTRODUCTION

This is a timely update of incidence and mortality for renal cell carcinoma (RCC) in the United States.

METHODS

Relying on the Surveillance, Epidemiology, and End Results (SEER) database, we computed age-adjusted incidence, mortality rates and 5-year cancer-specific survival (CSS) for patients with histologically confirmed kidney cancer between 1975 and 2009. Long-term (1975-2009) and short-term (2000-2009) trends were examined by joinpoint analysis, and quantified using the annual percent change (APC). The reported findings were stratified according to disease stage.

RESULTS

Age-adjusted incidence rates of RCC increased by +2.76%/year between 1975 and 2009 (from 6.5 to 17.1/100 000 person-years, p < 0.001), and by +2.85%/year between 2000 and 2009 (p < 0.001). For the same time points, the corresponding APC for the incidence of localized stage were +4.55%/year (from 3.0 to 12.2/100 000 person years, p < 0.001), and +4.42%/year (p < 0.001), respectively. The incidence rates of regional stage increased by +0.88%/year between 1975 and 2009 (p < 0.001), but stabilized in recent years (2000-2009: +0.56%/year, p = 0.4). Incidence rates of distant stage remained unchanged in long- and short-term trends. Overall mortality rates increased by +1.72%/year between 1975 and 2009 (from 1.2 to 5.0/100 000 person-years, P<0.001), but stabilized between 1994 and 2004 (p = 0.1). Short-term mortality rates increased in a significant fashion by +3.14%/year only for localized stage (p < 0.001).

INTERPRETATION

In contemporary years, there is a persisting upward trend in incidence and mortality of localized RCC.

MRI phenotype in renal cancer: is it clinically relevant?

Renal cell carcinoma (RCC) is most commonly diagnosed as an incidental finding on cross-sectional imaging and represents a significant clinical challenge. Although most patients have a surgically curable lesion at the time of diagnosis, the variability in the biologic behavior of the different histologic subtypes and tumor grade of RCC, together with the increasing array of management options, creates uncertainty for the optimal clinical approach to individual patients. State-of-the-art magnetic resonance imaging (MRI) provides a comprehensive assessment of renal lesions that includes multiple forms of tissue contrast as well as functional parameters, which in turn provides information that helps to address this dilemma. In this article, we review this evolving and increasingly comprehensive role of MRI in the detection, characterization, perioperative evaluation, and assessment of the treatment response of renal neoplasms. We emphasize the ability of the imaging "phenotype" of renal masses on MRI to help predict the histologic subtype, grade, and clinical behavior of RCC.

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.

Adverse health outcomes associated with surgical management of the small renal mass

PURPOSE

Partial and radical nephrectomy are treatments for the small renal mass. Partial nephrectomy is considered the gold standard as it may protect against renal dysfunction compared to radical nephrectomy. However, both treatments may cause adverse health outcomes.

MATERIALS AND METHODS

A matched cohort study was performed using the SEER (Surveillance, Epidemiology and End Results)-Medicare data set. Individuals treated with partial or radical nephrectomy for 4 cm or smaller nonmetastatic renal cell carcinoma were compared to 2 control groups (nonmuscle invasive bladder cancer and noncancer). A greedy algorithm matched surgical groups to controls. Medicare claims were examined for renal, cardiovascular and secondary cancer events.

RESULTS

Patients who underwent partial nephrectomy (1,471) and radical nephrectomy (4,299) were matched to controls. The time to event model demonstrated an increased risk of renal events for both treatments. Compared to the bladder cancer control and noncancer control groups, radical nephrectomy hazard ratios for renal events were 2.415 (p <0.0001) and 6.211 (p <0.0001), respectively, while partial nephrectomy hazard ratios were 1.513 (p <0.0001) and 4.926 (p <0.0001), respectively. Secondary cancers were increased for partial nephrectomy and radical nephrectomy compared to both control groups (p <0.0001). Cardiovascular events were increased for both treatments compared to noncancer controls (p <0.0001), but not compared to bladder cancer controls.

CONCLUSIONS

Partial nephrectomy and radical nephrectomy may lead to adverse health outcomes. Compared to controls, partial nephrectomy and radical nephrectomy are associated with worsened renal outcomes. The increase in secondary cancers and cardiovascular events with both treatments is notable, and requires further investigation. Further research should investigate if active surveillance of the appropriately selected small renal mass limits adverse health outcomes.