Natural history of renal masses followed expectantly

Scientific Status Quo of Small Renal Lesions: Diagnostic Assessment and Radiomics

Background: Small renal masses (SRMs) are defined as contrast-enhanced renal lesions less than or equal to 4 cm in maximal diameter, which can be compatible with stage T1a renal cell carcinomas (RCCs). Currently, 50-61% of all renal tumors are found incidentally. Methods: The characteristics of the lesion influence the choice of the type of management, which include several methods SRM of management, including nephrectomy, partial nephrectomy, ablation, observation, and also stereotactic body radiotherapy. Typical imaging methods available for differentiating benign from malignant renal lesions include ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI). Results: Although ultrasound is the first imaging technique used to detect small renal lesions, it has several limitations. CT is the main and most widely used imaging technique for SRM characterization. The main advantages of MRI compared to CT are the better contrast resolution and tissue characterization, the use of functional imaging sequences, the possibility of performing the examination in patients allergic to iodine-containing contrast medium, and the absence of exposure to ionizing radiation. For a correct evaluation during imaging follow-up, it is necessary to use a reliable method for the assessment of renal lesions, represented by the Bosniak classification system. This classification was initially developed based on contrast-enhanced CT imaging findings, and the 2019 revision proposed the inclusion of MRI features; however, the latest classification has not yet received widespread validation. Conclusions: The use of radiomics in the evaluation of renal masses is an emerging and increasingly central field with several applications such as characterizing renal masses, distinguishing RCC subtypes, monitoring response to targeted therapeutic agents, and prognosis in a metastatic context.

The need for evolutionary theory in cancer research

Sir Richard Peto is well known for proposing puzzling paradoxes in cancer biology-some more well-known than others. In a 1984 piece, Peto proposed that after decades of molecular biology in cancer research, we are still ignorant of the biology underpinning cancer. Cancer is a product of somatic mutations. How do these mutations arise and what are the mechanisms? As an epidemiologist, Peto asked if we really need to understand mechanisms in order to prevent cancer? Four decades after Peto's proposed ignorance in cancer research, we can simply ask, are we still ignorant? Did the great pursuit to uncover mechanisms of cancer eclipse our understanding of causes and preventions? Or can we get closer to treating and preventing cancer by understanding the underlying mechanisms that make us most vulnerable to this disease?

"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.

How We Do It: Managing the Indeterminate Renal Mass with the MRI Clear Cell Likelihood Score

The widespread use of cross-sectional imaging has led to a continuous increase in the number of incidentally detected indeterminate renal masses. Frequently, these clinical scenarios involve an older patient with comorbidities and a small renal mass (≤4 cm). Despite aggressive treatment in early stages of the disease, a clear positive effect in reducing kidney cancer-specific mortality is lacking, indicating that many renal cancers exhibit an indolent oncologic behavior. Furthermore, in general, one in five small renal masses is histologically benign and may not benefit from aggressive treatment. Although active surveillance is increasingly recognized as a management option for some patients, the absence of reliable clinical and imaging predictive biologic markers of aggressiveness can contribute to patient anxiety and limit its use in clinical practice. A standardized approach to the image interpretation of solid renal masses has not been broadly implemented. The clear cell likelihood score (ccLS) derived from multiparametric MRI is useful in noninvasively identifying the clear cell subtype, the most common and aggressive form of kidney cancer. Herein, a review of the ccLS is presented, including a step-by-step guide for image interpretation and additional guidance for its implementation in clinical practice.

Comparative outcomes of radio frequency ablation versus partial nephrectomy for T1 renal tumors: a systematic review

Background

The role of radio frequency ablation (RFA) in small renal tumors remains controversial. This systematic review was performed to compare clinical outcomes of RFA versus partial nephrectomy (PN) for the treatment of T1 renal tumors.

Methods

A total of 11 studies including 2,397 patients were analyzed in this systematic review after searching the databases of PubMed, EMBASE and Web of Science. P value and odds ratio (OR)/hazard ratio (HR) with 95% confidence interval (CI) were used to evaluate the strength of the association.

Results

A total of six studies (2,056 patients) provided either survival curves or HR and its 95% CI, demonstrating that the majority of the patients with RFA treatment tended to exhibit a similar long-term survival rate to those with PN treatment. In addition, according to four studies, no differences were found in the overall rate of complications between the two groups. Furthermore, there were significant differences in glomerular filtration rate (GFR) change between the two methods in four studies but no differences were observed in other two.

Conclusions

Our systematic review indicated that RFA is an effective treatment option which could provide comparable oncologic outcomes to PN. Moreover, it may present obvious advantages in renal function preservation.

Surveillance versus ablation for incidentally diagnosed small renal tumours: the SURAB feasibility RCT

BACKGROUND

There is uncertainty around the appropriate management of small renal tumours. Treatments include partial nephrectomy, ablation and active surveillance.

OBJECTIVES

To explore the feasibility of a randomised trial of ablation versus active surveillance.

DESIGN

Two-stage feasibility study: stage 1 - clinician survey and co-design work; and stage 2 - randomised feasibility study with qualitative and economic components.

METHODS

Stage 1 - survey of radiologists and urologists, and development of patient information materials. Stage 2 - patients identified across eight UK centres with small renal tumours (< 4 cm) were randomised (1 : 1 ratio) to ablation or active surveillance in an unblinded manner. Randomisation was carried out by a central computer system. The primary objective was to determine willingness to participate and to randomise a target of 60 patients. The qualitative and economic data were collected separately.

RESULTS

The trial was conducted across eight centres, with a site-specific period of recruitment ranging from 3 to 11 months. Of the 154 patients screened, 36 were eligible and were provided with study details. Seven agreed to be randomised and one patient was found ineligible following biopsy results. Six patients (17% of those eligible) were randomised: three patients received ablation and no serious adverse events were recorded. The 3- and 6-month data were collected for four (67%) and three (50%) out of the six patients, respectively. The qualitative substudy identified factors directly impacting on the recruitment of this trial. These included patient and clinician preferences, organisational factors (variation in clinical pathway) and standard treatment not included. The health economic questionnaire was designed and piloted; however, the sample size of recruited patients was insufficient to draw a conclusion on the feasibility of the health economics.

CONCLUSIONS

The trial did not meet the criteria for progression and the recruitment rate was lower than hypothesised, demonstrating that a full trial is presently not possible. The qualitative study identified factors that led to variation in recruitment across the sites. Implementation of organisational and operational measures can increase recruitment in any future trial. There was insufficient information to conduct a full economic analysis.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN31161700.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 81. See the NIHR Journals Library website for further project information.

Cepharanthine Enhances TRAIL-Mediated Apoptosis Through STAMBPL1-Mediated Downregulation of Survivin Expression in Renal Carcinoma Cells

Cepharanthine (CEP) is a natural plant alkaloid, and has anti-inflammatory, antineoplastic, antioxidative and anticancer properties. In this study, we investigated whether CEP could sensitize renal carcinoma Caki cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. CEP alone and TRAIL alone had no effect on apoptosis. However, combined CEP and TRAIL treatment markedly enhanced apoptotic cell death in cancer cells, but not in normal cells. CEP induced downregulation of survivin and cellular-FLICE inhibitory protein (c-FLIP) expression at post-translational levels. Ectopic expression of survivin blocked apoptosis by combined treatment with CEP plus TRAIL, but not in c-FLIP overexpression. Interestingly, CEP induced survivin downregulation through downregulation of deubiquitin protein of STAM-binding protein-like 1 (STAMBPL1). Overexpression of STAMBPL1 markedly recovered CEP-mediated survivin downregulation. Taken together, our study suggests that CEP sensitizes TRAIL-mediated apoptosis through downregulation of survivin expression at the post-translational levels in renal carcinoma cells.

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.

Ultrasound-guided percutaneous radiofrequency ablation for treating small renal masses

INTRODUCTION

The objective of this study was to analyse and assess the experience with radiofrequency ablation of small renal masses using a contrast-enhanced, ultrasound-guided percutaneous approach for patients who are not suitable for surgical resection and/or who refused surveillance or observation.

MATERIAL AND METHOD

From January 2007 to August 2015, 164 treatments were performed on a total of 148 patients. We present the patients' clinical-radiological characteristics, oncological and functional results in the short and medium term.

RESULTS

The overall technical success rate was 97.5%, with a successful outcome in 1 session in 100% of the lesions≤3cm and 92% in lesions measuring 3-5cm. The mean tumour diameter in the patients for whom the treatment was ultimately successful was 2.7cm, while the mean diameter of these in the unsuccessful operations was 3.9cm (P<.05). There were no statistically significant differences in the serum creatinine levels and estimated glomerular filtration rates.

CONCLUSIONS

Despite the low rate of positive renal biopsies in the series, ultrasound-guided percutaneous radiofrequency ablation for treating small renal lesions appears to be an effective and safe procedure with a minimum impact on renal function, an acceptable oncologic control in the short and medium term and a low rate of complications.

Active Surveillance of Nonfatty Renal Masses in Patients With Lymphangioleiomyomatosis: Use of CT Features and Patterns of Growth to Differentiate Angiomyolipoma From Renal Cancer

OBJECTIVE

The objective of this study was to report our experience with active surveillance of nonfatty renal masses in a large cohort of patients with lymphangioleiomyomatosis (LAM), correlate their CT features and patterns of growth with histopathology results, and provide guidelines for management.

SUBJECTS AND METHODS

Yearly CT examinations were performed of 367 women (age range, 21-75 years; mean age, 47 years). For the 31 patients with 37 nonfatty renal masses that were biopsied, excised, or followed for ≥ 5 years, CT enhancement characteristics and patterns of growth were compared with the histopathology results.

RESULTS

Four of 37 nonfatty renal masses were biopsied without follow-up CT examinations: Two were heterogeneous renal cell carcinomas (RCCs), one was a heterogeneous nonfatty angiomyolipoma (AML), and one was homogeneous nonfatty AML. In the remaining 33 nonfatty renal masses with multiple follow-up CT examinations, two growth patterns were identified. Four showed a continuous increase in size of > 0.5 cm/y in some years, and all four in this first group were heterogeneous and were biopsy-proven RCC. The second group was composed of the remaining 29 masses. These 29 masses showed yearly no change, increase, or decrease in diameter. Eight were heterogeneous, and 21 were homogeneous. Of the masses showing a yearly increase, the increase was < 0.5 cm/y in all except one. In the one exception, the increase followed a decrease. Nine of the 29 masses were biopsied, and all nine were nonfatty renal masses (five homogeneous, four heterogeneous).

CONCLUSION

Our data provide further evidence in a large prospective study with longterm follow-up that active surveillance is an appropriate strategy in the management of nonfatty renal masses in patients with LAM. Our analysis of the growth patterns reveals duration of growth in addition to growth rate as criteria for biopsy or excision. Biopsy should be reserved for nonfatty renal masses that show sustained growth or growth > 0.5 cm/y during follow-up.

Renal Tumor Biopsy Technique

Objective:

To review hot issues and future direction of renal tumor biopsy (RTB) technique.

Data Sources:

The literature concerning or including RTB technique in English was collected from PubMed published from 1990 to 2015.

Study Selection:

We included all the relevant articles on RTB technique in English, with no limitation of study design.

Results:

Computed tomography and ultrasound were usually used for guiding RTB with respective advantages. Core biopsy is more preferred over fine needle aspiration because of superior accuracy. A minimum of two good-quality cores for a single renal tumor is generally accepted. The use of coaxial guide is recommended. For biopsy location, sampling different regions including central and peripheral biopsies are recommended.

Conclusion:

In spite of some limitations, RTB technique is relatively mature to help optimize the treatment of renal tumors.

Management of Small Renal Masses: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide recommendations for the management options for patients with small renal masses (SRMs). Methods By using a literature search and prospectively defined study selection, we sought systematic reviews, meta-analyses, randomized clinical trials, prospective comparative observational studies, and retrospective studies published from 2000 through 2015. Outcomes included recurrence-free survival, disease-specific survival, and overall survival. Results Eighty-three studies, including 20 systematic reviews and 63 primary studies, met the eligibility criteria and form the evidentiary basis for the guideline recommendations. Recommendations On the basis of tumor-specific findings and competing risks of mortality, all patients with an SRM should be considered for a biopsy when the results may alter management. Active surveillance should be an initial management option for patients who have significant comorbidities and limited life expectancy. Partial nephrectomy (PN) for SRMs is the standard treatment that should be offered to all patients for whom an intervention is indicated and who possess a tumor that is amenable to this approach. Percutaneous thermal ablation should be considered an option if complete ablation can reliably be achieved. Radical nephrectomy for SRMs should only be reserved for patients who possess a tumor of significant complexity that is not amenable to PN or for whom PN may result in unacceptable morbidity even when performed at centers with expertise. Referral to a nephrologist should be considered if chronic kidney disease (estimated glomerular filtration rate < 45 mL/min/1.73 m²) or progressive chronic kidney disease occurs after treatment, especially if associated with proteinuria.

In vivo irreversible electroporation kidney ablation: experimentally correlated numerical models

Irreversible electroporation (IRE) ablation uses brief electric pulses to kill a volume of tissue without damaging the structures contraindicated for surgical resection or thermal ablation, including blood vessels and ureters. IRE offers a targeted nephron-sparing approach for treating kidney tumors, but the relevant organ-specific electrical properties and cellular susceptibility to IRE electric pulses remain to be characterized. Here, a pulse protocol of 100 electric pulses, each 100 μs long, is delivered at 1 pulse/s to canine kidneys at three different voltage-to-distance ratios while measuring intrapulse current, completed 6 h before humane euthanasia. Numerical models were correlated with lesions and electrical measurements to determine electrical conductivity behavior and lethal electric field threshold. Three methods for modeling tissue response to the pulses were investigated (static, linear dynamic, and asymmetrical sigmoid dynamic), where the asymmetrical sigmoid dynamic conductivity function most accurately and precisely matched lesion dimensions, with a lethal electric field threshold of 575 ± 67 V/cm for the protocols used. The linear dynamic model also attains accurate predictions with a simpler function. These findings can aid renal IRE treatment planning under varying electrode geometries and pulse strengths. Histology showed a wholly necrotic core lesion at the highest electric fields, surrounded by a transitional perimeter of differential tissue viability dependent on renal structure.

Optimal follow-up intervals in active surveillance of renal masses in patients with von Hippel-Lindau disease

OBJECTIVES

To estimate an optimal follow-up (FU) interval for von Hippel-Lindau (VHL) patients with renal masses (RMs) by determining tumour growth rates from growth curves.

METHODS

Thirty lesions (47.6%) were classified as solid tumours (STs) and 33 (52.4%) as complex cysts (CCs). Variations in lesion volume over time were analyzed. For 53 lesions, we calculated the growth rate during the period when the volume of the lesion changed most rapidly, and called this the fast growth rate (FGR).

RESULTS

The STs initially grew fast, followed by a period of slower growth. The CCs varied in volume over time, associated with variable amounts of their fluid component. The FGR correlated better with the latest volume for STs (r = 0.905) than for CCs (r = 0.780). An optimal FU interval between 3 and 12 months was derived by combining the FGR calculated from the curve with the latest volume measured.

CONCLUSIONS

Analyzing growth curves and related kinetic parameters for RMs in VHL patients could be useful with a view to optimizing the subsequent FU interval and improving the active surveillance program.

KEY POINTS

• Measuring volume changes over time enables tumour growth curves to be charted. • Renal solid tumours increase in volume with a typical sigmoidal curve. • Complex cysts may increase and decrease in volume spontaneously over time. • The fast growth rate of solid tumours correlates with their latest volume. • The fast growth rate can orient the scheduling of subsequent follow-ups.

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.

Thinking beyond surgery in the management of renal cell carcinoma: the risk to die from renal cell carcinoma and competing risks of death

INTRODUCTION

The presentation of renal cell carcinoma (RCC) has changed where it is most commonly identified when asymptomatic and incidental. Contemporary patients with renal tumors are often older in age and may have significant concurrent medical comorbidity, where proceeding with routine surgical treatment may not be of benefit. Traditional clinical assessments have not considered the impact of comorbidity on oncologic outcome, and recent studies have demonstrated the relationship between comorbidity and patient survival. We review the existing data examining the significance of medical comorbidity on RCC management and outcomes.

MATERIALS AND METHODS

The existing literature on this topic is reviewed, and validated measures of comorbidity are described. The available studies examining the relationship between comorbidity and RCC are summarized.

RESULTS AND DISCUSSION

The article reviews the growing body of literature supporting the importance of assessment of patient comorbidity, and we highlight novel prognostic instruments that can estimate the likelihood of several different patient outcomes following RCC treatment, and these nomograms can be accessed via a web-based portal ( www.cancernomograms.com ) to assist in patient education and clinical decision making.

Extensive renal infarction following percutaneous biopsy of a small renal mass: A case report

Percutaneous renal biopsy has become increasingly used particularly in patients undergoing active surveillance for small renal masses. We present a patient, who was recently diagnosed with laryngeal squamous cell carcinoma, with significant complication following biopsy of a solid renal mass. The patient was planned for nephron-sparing surgery that was converted to radical nephrectomy due to extensive renal infarction secondary to significant subcapsular hemorrhage inflicted by the biopsy.

Illness uncertainty and quality of life of patients with small renal tumors undergoing watchful waiting: a 2-year prospective study

BACKGROUND

Few studies have examined factors associated with the quality of life (QOL) of patients with renal tumors. Illness uncertainty may influence QOL.

OBJECTIVE

To prospectively examine the influence of uncertainty on general and cancer-specific QOL and distress in patients undergoing watchful waiting (WW) for a renal mass.

DESIGN, SETTING, AND PARTICIPANTS

In 2006-2010, 264 patients were enrolled in a prospective WW registry. The decision for WW was based on patient, tumor, and renal function characteristics at the discretion of the urologist and medical oncologist in the context of the physician-patient interaction. Participants had suspected clinical stage T1-T2 disease, were aged ≥ 18 yr, and spoke and read English. The first 100 patients enrolled in the registry participated in this study.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Patients completed questionnaires on demographics, illness uncertainty (Mishel Uncertainty in Illness Scale), general QOL (Medical Outcomes Study 36-item short-form survey), cancer-specific QOL (Cancer Rehabilitation Evaluation System-Short Form), and distress (Impact of Events Scale) at enrollment and at 6, 12, and 24 mo. Age, gender, ethnicity, tumor size, estimated glomerular filtration rate, comorbidities, and assessment time point were controlled for in the models.

RESULTS AND LIMITATIONS

Among the sample, 27 patients had biopsies, and 17 patients had proven renal cell carcinoma. Growth rate was an average of 0.17 cm/yr (standard deviation: 0.35). Mean age was 72.5 yr, 55% of the patients were male, and 84% of the patients were Caucasian. Greater illness uncertainty was associated with poorer general QOL scores in the physical domain (p=0.008); worse cancer-related QOL in physical (p=0.001), psychosocial (p<0.001), and medical (p=0.034) domains; and higher distress (p<0.001).

CONCLUSIONS

This study is among the first to prospectively examine the QOL of patients with renal tumors undergoing WW and the psychosocial factors that influence QOL. Illness uncertainty predicted general QOL, cancer-specific QOL, and distress. These factors could be targeted in psychosocial interventions to improve the QOL of patients on WW.

Thermoablation of Renal Masses: The Urologist's Perspective

Thermoablation (TA) has become an increasingly popular treatment for small renal masses (SRMs). Although long-term outcomes are not currently reported, TA may have a role in being an alternative to radical or partial nephrectomy. This review gives a broad overview of TA and discusses current controversies in the field.

Active surveillance: a potential strategy for select patients with small renal masses

Increased abdominal imaging has led to the significant incidental detection of clinically localized renal masses. While the gold standard remains surgical excision, mortality rates from kidney cancer remain relatively unchanged implying that a proportion of small renal masses may be indolent tumors that do not require surgical intervention. As a result, active surveillance has emerged as an alternative management strategy in select patients with significant competing risks. Although the contemporary literature characterizing the natural history of untreated small renal masses is limited, recent data demonstrate that many incidental renal masses demonstrate slow growth kinetics with a low rate of progression to metastatic disease over an intermediate time period. Prospective trials are necessary to define entry and intervention criteria for active surveillance protocols.

Progression to metastatic disease from a small renal cell carcinoma prospectively followed with an active surveillance protocol

With the widespread use of abdominal imaging to evaluate other medical conditions, many renal tumours are being diagnosed at earlier stages. Older patients have experienced the most significant increase in the incidence of renal cell carcinoma (RCC). This age group frequently has significant medical comorbidities. This has led to the concept of active surveillance for select patients with renal lesions that may not affect their mortality. However, the ultimate risk of active surveillance is the potential for developing metastases. This case report presents the development of metastatic disease from a small, incidentally detected and prospectively followed RCC with asymptomatic progression.

Watchful waiting in the treatment of the small renal mass

Objectives:

To evaluate the role and feasibility of observation with regard to the small renal mass.

Methods:

We performed a literature search of MEDLINE, reviewing the world literature relevant to the natural history, role of percutaneous biopsy and surveillance of the small renal mass.

Results:

The average yearly growth rate of most small renal masses ranges from 0.1 to 0.70 cm/yr with obvious exceptions. Clinical predictors of growth such as radiographic size at presentation, age, gender and tumor characteristics are not reliable. Approximately 1% develops metastatic disease while under surveillance. Contemporary series of percutaneous biopsy of small renal masses report sensitivity for malignancy to be 90%-98%. However, false-negative results can occur. For the majority of patients, the gold standard remains surgical extirpation.

Conclusions:

Watchful waiting is an acceptable option for management of small renal masses in the surgically unfit and elderly population. More information regarding the natural history and metastatic potential of small renal masses is needed. Percutaneous needle biopsy can be successful in detecting malignancy in selected patients with small renal masses. The role of needle biopsy for the small renal mass continues to evolve

FEM-based 3-D tumor growth prediction for kidney tumor

It is important to predict the tumor growth so that appropriate treatment can be planned in the early stage. In this letter, we propose a finite-element method (FEM)-based 3-D tumor growth prediction system using longitudinal kidney tumor images. To the best of our knowledge, this is the first kidney tumor growth prediction system. The kidney tissues are classified into three types: renal cortex, renal medulla, and renal pelvis. The reaction-diffusion model is applied as the tumor growth model. Different diffusion properties are considered in the model: the diffusion for renal medulla is considered as anisotropic, while those of renal cortex and renal pelvis are considered as isotropic. The FEM is employed to solve the diffusion model. The model parameters are estimated by the optimization of an objective function of overlap accuracy using a hybrid optimization parallel search package. The proposed method was tested on two longitudinal studies with seven time points on five tumors. The average true positive volume fraction and false positive volume fraction on all tumors is 91.4% and 4.0%, respectively. The experimental results showed the feasibility and efficacy of the proposed method.

Active surveillance of renal cortical neoplasms: a contemporary review

INTRODUCTION

Over the past 2 decades, there has been a significant increase in the number of incidentally found small renal cortical neoplasms (RCNs). As more RCNs are being discovered in the elderly and infirmed patient populations, there has been a growing interest in the role of active surveillance (AS). Active surveillance is recommended for high surgical-risk patients and those with a reduced life expectancy. It is also an option for patients wishing to avoid surgery. We review the current literature on AS and highlight the natural history of disease, the important factors to evaluate during AS, and the contemporary role of biopsy.

METHODS AND MATERIALS

The MEDLINE database was searched using PubMed. Search terms included active surveillance, renal mass, natural history, and renal mass histology. From 1966 to present, 17 AS series were identified, all of which have been included in this summary. A summary was performed by compiling all available data and performing a weighted mean where applicable.

RESULTS

Initial tumor size does not correlate with growth rate or malignancy. The mean growth rate in large published series is low (0.28-0.34 cm/year). Tumors with high growth rates usually represent malignant lesions and typically undergo delayed intervention. Progression to metatatic disease is a low-probability event for tumors on AS (1.4%); however, this is still a risk that patients must be willing to accept. Larger tumors (cT1b and cT2) also demonstrate relatively low growth (0.57 cm/year); however, these tumors should be monitored carefully. Tumors followed for > 5 years demonstrate a low growth rate (0.15 cm/year), will not likely require intervention, and have a low chance of progression to metastatic disease.

CONCLUSION

For highly selected patients with RCN, AS is a reasonable treatment option. Age, surgical risk, comorbidities, and patient opinion must all factor into the final decision when considering a patient for AS.

Renal mass sampling: an enlightened perspective

Renal mass sampling (RMS) can be carried out by core biopsy or fine needle aspiration with each presenting potential advantages and limitations. The literature about RMS is confounded by a lack of standardized techniques, ambiguous terminology, imprecise definitions of accuracy, substantial rates of non-informative biopsies, and recurrent diagnostic challenges with respect to eosinophilic neoplasms. Despite these concerns, RMS has an expanding role in the evaluation and treatment of renal masses, in order to stratify biological aggressiveness and guide management that can range from surgery to active surveillance. Non-informative biopsies can be managed with surgical excision or repeat biopsy, with the latter showing encouraging results in recent studies. We propose a new classification in which all biopsies are categorized as non-informative versus informative, with the latter being subclassified as confirmed accurate, presumed accurate or confirmed inaccurate. This terminology will facilitate the comparison of results from various studies and stimulate progress. Incorporation of novel biomarkers and molecular fingerprinting into RMS protocols will likely allow for more rational management of patients with renal masses in the near future.

Natural history and management of small renal masses

The recent stage migration observed for renal tumours is contributing to a significant increase in the diagnosis of small renal masses. This evolution has led to a significant change in the approach to renal masses. New options such as observation or energy ablation are gaining popularity in a subset of this patient population. In addition, the observed changes directly contribute to the increased use of nephron-sparing surgery. A better understanding of the various characteristics of these masses will allow for a better understanding of the natural history of these masses and for selection of the optimal therapeutic approach.

Treatment of renal tumors by percutaneous ultrasound-guided radiofrequency ablation using a multitined electrode: effectiveness and complications

BACKGROUND

Radiofrequency ablation (RFA) is a minimally aggressive, therapeutic alternative for renal tumors. It can be an alternative to nephrectomy in patients with previous nephrectomy, bilateral tumors, von Hippel-Lindau disease, or small renal carcinomas and in those with contraindications for surgery.

OBJECTIVE

To assess the effectiveness of the treatment of renal tumors by RFA in the short and medium term and to identify the possible complications and the factors that determine therapeutic success.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective review of patients with renal tumors treated with RFA between May 2005 and December 2008 was performed in a tertiary academic hospital. Patients were selected among those with previous nephrectomy, bilateral neoplasms, von Hippel-Lindau disease, surgical risk, comorbidity, advanced age, or patient's refusal to surgery. Tumors with evidence of extrarenal extension were excluded. Patients were followed up for 10-50 mo using computed tomography and magnetic resonance imaging.

INTERVENTION

Ultrasound-guided RFA was performed on 65 tumors (range: 1.2-5.3 cm) of 58 patients using multitined electrodes.

MEASUREMENTS

Incomplete ablation rate, therapeutic success rate, and complications rate.

RESULTS AND LIMITATIONS

Therapeutic success was achieved in 59 of 65 tumors (91%): 53 in a single session, 5 in two sessions, and 1 in three sessions. A significant relationship was observed between size and growth pattern of the tumor and both therapeutic success and incomplete ablation rates. Therapeutic success in tumors >5 cm was 60%. Complications were detected in 10 patients (13%); 5% were considered major complications. Limitations include the lack of pathologic studies to confirm a complete ablation and the lack of a control group to compare with the results of those who underwent nephrectomy.

CONCLUSIONS

RFA is safe and effective in renal tumors. Corticomedullary lesions and tumors >3 cm have greater possibility of incomplete ablation. In tumors >5 cm, RFA has a significant failure rate.

Imaging and management of the incidentally discovered renal mass

Improvements in imaging technology and the expanding use of imaging have led to a rapid increase in the discovery of incidental renal lesions. These can present both the radiologist and the referring clinician with diagnostic dilemmas. This article addresses the most frequently encountered lesions and provides a framework for the diagnostic and management pathways for both solid and cystic lesions.

[Current treatment of small renal masses]

Incidental diagnosis of renal carcinoma (RC) is increasingly common due to widespread use of radiodiagnostic techniques for other conditions. In developed countries, incidental tumor account for more than 40% of detected tumors, and 80% of solid kidney tumors less than 4 cm in size are malignant. Standard treatment for these tumors is partial nephrectomy, and their relapse rate is 1%-2% The higher increase in diagnosis of this disease has occurred in patients aged 70 to 90 years, a group where associated comorbidities are very common. In the past two decades, in parallel to development of radiographic techniques, two ablation procedures achieving tumor necrosis through cold, cryotherapy, and through heat, radiofrequency, have become established. These procedures achieve 95% short- and long-term remissions in tumors less than 4 cm in size. In addition, since these procedures may be performed percutaneously, both complications and hospital stay have decreased. As early as in 1995, Bosniak, based on observation of the growth and behavior of small RCs for longer than 8 years, advocated a watchful waiting or active surveillance attitude. This article reports cryotherapy, our radiofrequency series, and a literature review.

CONCLUSIONS

In the event of elderly patients, concomitant diseases advising against surgery, multiple renal tumors, a solitary kidney, or patients who reject surgery, ablation procedures may be safe and effective when performed by expert hands, achieving mid-term oncological results similar to partial nephrectomy. Active surveillance has also been shown to be safe in the mid-term in adequately informed patients. To improve indications, new diagnostic procedures that help us differentiate the potentially more aggressive tumors will be required. Larger series and longer follow-ups are neede to confirm current results.