Enhancing renal masses with zero net growth during active surveillance

Prospective analysis of the safety and efficacy of percutaneous cryoablation for pT1NxMx biopsy-proven renal cell carcinoma

PURPOSE

Our objective was to determine the efficacy and safety of image-guided, percutaneous cryoablation for American Joint Committee on Cancer pT1ANxMx and pT1BNxMx biopsy-proven renal cell carcinoma (RCC).

MATERIALS AND METHODS

Computed tomography (CT)-guided, percutaneous cryoablation was used to treat 117 renal lesions in 113 consecutive patients with pT1NxMx RCC. All 117 ablations were included in the safety analysis, and complications were categorized according to Common Terminology Criteria for Adverse Events version 3.0 (CTCAE v3.0). Eighty-one lesions were biopsy-proven RCC and were included in the efficacy analysis. Technical success was defined as the "ice-ball" covering the entire lesion plus a minimum 5-mm margin. Efficacy was defined as complete lack of enhancement and continuous decrease in size on subsequent follow-up imaging studies.

RESULTS

Technical success was 100%, with 15% of ablations requiring air or saline injection to prevent nontarget ablation. We recorded a 7% rate of clinically significant complications (CTCAE category≥2) and 0% mortality. Renal function was not adversely affected. Seventy percent of patients were discharged to home on the same day. Efficacy was 98.7% for a median follow-up of 67 weeks (range 7-172). For the subgroup of patients that reached a median follow-up of 2 (n=59) and 3 years (n=13), efficacy was 98.3 and 92.3%, respectively. Cancer specific survival was 100%.

CONCLUSIONS

CT-guided, percutaneous cryoablation has an excellent safety and efficacy profile for stage T1A and T1B RCC; however, longer follow-up is needed to compare it with other nephron-sparing surgical treatments. It is a great option for nonsurgical patients, those in whom renal function cannot be further sacrificed, and those at risk for metachronous lesions.

Small renal masses: current concepts regarding the natural history and reflections on the American Urological Association guidelines

PURPOSE OF REVIEW

Although surgical resection is the current standard for treatment of small (<4 cm) renal cortical neoplasms, active surveillance remains an option in selected patients depending on tumor characteristics and surgical risk. We review the natural history of small renal masses according to the current literature, and highlight issues regarding the recent guidelines for the management of T1 renal masses put forth by the American Urological Association.

RECENT FINDINGS

The natural history of small renal masses is still largely unknown; however, initial size or volume of the mass seems to predict the risk of malignancy in retrospective studies. A new study found that growth rate is inversely related to initial tumor volume, with smaller masses growing faster in the beginning and decreasing in rate of growth as they enlarge. Biomarkers such as carbonic anhydrase IX, vascular endothelial growth factor, and CD147 have demonstrated some value in predicting tumor characteristics and prognosis in renal cell carcinoma. Finally, we suggest modifications to the new American Urological Association guidelines based on the authors' experience in order to optimize the management of renal cortical neoplasms.

SUMMARY

The natural history of small renal masses is not completely understood. Growth rate and tumor size are factors shown to be predictive of tumor biology. Currently, there are no specific tumor markers to determine initial risk or progression to metastatic disease; however, investigation into new molecules is being undertaken. The guidelines presented by the American Urological Association give a formal framework for the management of T1 renal cortical neoplasms; however, we site specific modifications and recommend that they be considered when evaluating patients for treatment.

Active surveillance for renal cortical neoplasms

PURPOSE

We retrospectively evaluated our single center experience with patients with renal cortical neoplasms who elected active surveillance.

MATERIALS AND METHODS

We retrospectively evaluated our urological oncology database between January 1993 and January 2009, identifying a total of 223 renal cortical neoplasms in 212 patients that were initially managed by active surveillance. We described patient and tumor characteristics, and assessed the differences between patients who remained on AS and those who underwent delayed intervention or progressed with metastasis.

RESULTS

Median patient age was 71 years at active surveillance initiation and the median Charlson comorbidity index was 3. Median tumor size was 2.8 cm (range 0.5 to 13.7) at study enrollment and 3.7 cm (range 0.9 to 14.1) at final assessment. The median growth rate in the entire cohort was 0.34 cm per year (range 0.29 to 2.3). Median followup was 35 months (range 6 to 137). Active surveillance failed in 15 patients (7%), of whom 4 (2%) progressed to metastasis and 11 (5%) required intervention. When comparing cases of failed active surveillance with those that continued, there were statistical differences in initial tumor size (2.61 vs 3.64 cm, p = 0.019), final tumor size (3.56 vs 5.17 cm, p = 0.001) and growth rate (0.34 vs 1.75, p = 0.001). There was no correlation between initial tumor size and growth rate (Pearson's coefficient r = 0.006, p = 0.932). A total of 14 patients died of another medical condition. Only 1 cancer related death (0.5%) was reported in the entire cohort.

CONCLUSIONS

Active surveillance for renal cortical neoplasms in select older patients with comorbidities is a reasonable treatment option. At 3-year followup we noted a 7% failure rate.

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.

Evaluating overall survival and competing risks of death in patients with localized renal cell carcinoma using a comprehensive nomogram

PURPOSE

Many patients with localized node-negative renal cell carcinoma (RCC) are elderly with competing comorbidities. Their overall survival benefit after surgical treatment is unknown. We reviewed cases in the Surveillance, Epidemiology, and End Results (SEER) database to evaluate the impact of kidney cancer versus competing causes of death in patients with localized RCC and develop a comprehensive nomogram to quantitate survival differences.

METHODS

We identified individuals with localized, surgically treated clear-cell, papillary, or chromophobe RCC in SEER (1988 through 2003). We used Fine and Gray competing risks proportional hazards regressions to predict 5-year probabilities of three competing mortality outcomes: kidney cancer death, other cancer death, and noncancer death.

RESULTS

We identified 30,801 cases of localized RCC (median age, 62 years; median tumor size, 4.5 cm). Five-year probabilities of kidney cancer death, other cancer death, and noncancer death were 4%, 7%, and 11%, respectively. Age was strongly predictive of mortality and most predictive of nonkidney cancer deaths (P < .001). Increasing tumor size was related to death from RCC and inversely related to noncancer deaths (P < .001). Racial differences in outcomes were most pronounced for nonkidney cancer deaths (P < .001). Men were more likely to die than women from all causes (P < .002). This nomogram integrates commonly available factors into a useful tool for comparing competing risks of death.

CONCLUSION

Management of localized RCC must consider competing causes of mortality, particularly in elderly populations. Effective decision making requires treatment trade-off calculations. We present a tool to quantitate competing causes of mortality in patients with localized RCC.

Biopsy of a renal mass: where are we now?

PURPOSE OF REVIEW

To review the most recent literature concerning renal mass biopsy with special consideration to three points: variation in results related to the standard used as comparison, biopsy in small renal masses (up to 4 cm in diameter) and the case for nondiagnostic biopsy.

RECENT FINDINGS

The overall rate of failed and indeterminate biopsies shows a trend for improvement. However, selection bias and the lack of a uniform index test for comparison preclude a definitive statement. Fine-needle aspiration may equal results of core biopsy, but its role in the diagnostic algorithm is not yet defined. In-vivo accuracy decreases in small renal masses with the same limitations exposed for the overall literature on renal mass biopsy. When nondiagnostic biopsies are considered, there is a need for standardization of the nomenclature in order to compare results. Re-biopsies or surgery after a nondiagnostic biopsy shows malignancy in up to 75% of the cases of renal cell carcinoma.

SUMMARY

There is a trend in increasing interest and accuracy on the subject of percutaneous biopsy of renal masses as well as a decreasing trend in the rate of nondiagnostic biopsies. In the small renal masses, most likely to be benign, a diagnostic percutaneous biopsy may have a definitive role. However, the higher rate of nondiagnostic results in this population calls for prospective studies with standard definitions and when possible homogenous index test to properly assess the diagnostic performance of the biopsy.

A critical analysis of the actual role of minimally invasive surgery and active surveillance for kidney cancer

CONTEXT

The incidence of renal cell carcinomas (RCCs) has increased steadily-most rapidly for small renal masses (SRMs). Paralleling the changing face of RCC in the past 2 decades, new, less invasive surgical options have been developed. Laparoscopic radical nephrectomy (LRN) is an established procedure for the treatment of RCC. Treatment of SRMs includes open partial nephrectomy (OPN), laparoscopic partial nephrectomy (LPN), thermal ablation, and active surveillance.

OBJECTIVE

To present an overview of minimally invasive treatment options and data on surveillance for kidney cancer.

EVIDENCE ACQUISITION

Literature and meeting abstracts were searched using the terms renal cell carcinoma, minimally invasive surgery, laparoscopic surgery, thermal ablation, surveillance, and robotic surgery. The articles with the highest level of evidence were identified with the consensus of all the collaborative authors and reviewed.

EVIDENCE SYNTHESIS

Renal insufficiency, as measured by the glomerular filtration rate, occurs more often after radical nephrectomy than partial nephrectomy (PN). OPN and LPN show comparable results in long-term oncologic outcomes. The treatment modality for SRMs should therefore be nephron-sparing surgery (NSS). In select patients, thermal ablation or active surveillance of SRMs is an alternative.

CONCLUSIONS

LRN has become the standard of care for most organ-confined tumours not amenable to NSS. Amongst NSS options, PN is the treatment of choice, yet remains underutilised in the community. Initial data during its learning curve revealed that LPN had higher urologic morbidity. However, current emerging data indicate that in experienced hands, LPN has shorter ischaemia times, a lower complication rate, and equivalent long-term oncologic and renal functional outcomes, yet with decreased patient morbidity compared to OPN. Robotic partial nephrectomy is being explored at select centres, and cryotherapy and radiofrequency ablation are options for carefully selected tumours. Active surveillance is an option for selected high-risk patients. Percutaneous needle biopsy is likely to gain increasing relevance in the management of small renal tumours.

The evolving management of small renal masses

The incidence of small renal masses (SRMs) continues to rise, largely because of the widespread use of cross-sectional imaging for abdominal symptomatology. Clinical management must balance the risk of disease progression from renal cell carcinoma in these tumors against the potential morbidity of treatment, particularly in elderly patients or those with multiple comorbidities. Moreover, a significant minority of SRMs represent benign lesions. This article reviews the current data for surgical excision, cryoablation, radiofrequency ablation, and active surveillance of SRMs. Surgical excision, predominantly in the form of nephron-sparing surgery, remains the standard of care because of its durable oncologic and favorable functional outcomes. Active surveillance and ablative technologies have emerged as alternatives to surgery in select patients based on short-term oncologic data. Nevertheless, the extent to which treatment alters the natural history of SRMs has yet to be established.

The growth rate of large renal masses opposes active surveillance

OBJECTIVE

To retrospectively determine the growth rate of renal masses with a diameter of > or =4 cm at the time of surgery, as the average growth rate of untreated small (<4 cm) renal masses is assumed to be 0.1-0.7 cm/year, but little is known about the progression of large masses.

PATIENTS AND METHODS

Of 256 patients who had their renal tumour surgically removed between January and December 2008, we identified nine (five men and four women; median age 65.2 years, range 29.2-74.2) with solitary large renal masses (>4 cm) who had abdominal imaging with identification of renal masses >6 months before admission. In none of the patients had the initial imaging led to admission, either by accident or because the masses were overlooked. The tumour growth rate was calculated based on images taken > or =6 months before admission and actual imaging, as well as histological results.

RESULTS

All patients had surgical resection of their renal masses in 2008. The median (range) follow-up from initial diagnosis to surgery was 14.6 (6.5-58.4) months. The median observed tumour growth rate was 6.41 (2.47-8.66) cm/year. The histological diagnosis was clear cell renal cell carcinoma (RCC) in seven patients, papillary in one and clear cell RCC with portions of sarcomatoid de-differentiation in one; two patients had lymph node metastases and one had pulmonary metastases, and five had tumours of > or =T3.

CONCLUSIONS

The growth rate of large tumours is much higher than of small renal masses and most patients present with advanced disease. Thus, tumours of > or =4 cm seem not to be candidates for active surveillance but require immediate therapy. Further studies are warranted to determine the clinical relevance of progressive tumour growth and the underlying mechanisms.

Understanding the relationship between health care quality and the renal mass

Quality is increasingly important to all stakeholders of the U.S. health care system. Endeavors to measure and improve quality have moved forward in cardiovascular disease, diabetes care, and surgical wound infections. However, in urology, such efforts have lagged. As a specialty, we are now faced with pressures, exerted primarily by payors, to roll out performance measures, or quality indicators, in the absence of science to support them. In this review, we discuss the broad concepts of health care quality and describe their relationships with small renal tumors.

Optimal management of localized renal cell carcinoma: surgery, ablation, or active surveillance

Radical nephrectomy is historically accepted as standard treatment for localized renal cell carcinoma (RCC). However, the presentation of RCC has changed dramatically over the past 3 decades. Newer alternative interventions aim to reduce the negative impact of open radical nephrectomy, with the natural history of RCC now better understood. This article discusses current surgical and management options for localized kidney cancer.

Natural history, growth kinetics, and outcomes of untreated clinically localized renal tumors under active surveillance

BACKGROUND

The growth kinetics of untreated solid organ malignancies are not defined. Radiographic active surveillance (AS) of renal tumors in patients unfit or unwilling to undergo intervention provides an opportunity to quantify the natural history of untreated localized tumors. The authors report the radiographic growth kinetics of renal neoplasms during a period of surveillance.

METHODS

The authors identified patients with enhancing renal masses who were radiographically observed for at least 12 months. Clinical and pathological records were reviewed to determine tumor growth kinetics and clinical outcomes. Tumor growth kinetics were expressed in terms of absolute and relative linear and volumetric growth.

RESULTS

The authors identified 172 renal tumors in 154 patients under AS. Median tumor diameter and volume on presentation were 2.0 cm (mean, 2.5; range, 0.4-12.0) and 4.18 cm(3) (mean, 20.0; range, 0.033-904). Median duration of follow-up was 24 months (mean, 31; range, 12-156). A significant association between presenting tumor size and proportional growth was noted, with smaller tumors growing faster than larger tumors. Thirty-nine percent (68 of 173) of tumors underwent delayed intervention, and 84% (57 of 68) were pathologically malignant. Progression to metastatic disease was noted in 1.3% (2 of 154) of patients.

CONCLUSIONS

The authors demonstrated the association between a tumor's volume and subsequent growth, with smaller tumors exhibiting significantly faster volumetric growth than larger tumors, consistent with Gompertzian kinetics. Surveillance of localized renal tumors is associated with a low rate of disease progression in the intermediate term, and suggests potential overtreatment biases in select patients.

Surveillance as an option for the treatment of small renal masses

OBJECTIVES. To review the natural history and biological potential of small renal masses in order to evaluate surveillance as a treatment option. METHODS. Literature search of Medline and additional references from non-Medline-indexed publications concerning surveillance of small renal masses. RESULTS. The natural history and biological potential of small renal masses can still not be unambiguously predicted at present. There seems to be no clear correlation between tumour size and presence of benign histology. The majority of small renal masses grow and the majority are cancer, but one cannot safely assume that a lack of growth on serial CT scans is the confirmation of absence of malignancy. Needle core biopsies could be used to help in decision making. They show a high accuracy for histopathological tumour type but are less accurate in evaluating Fuhrman grade. CONCLUSIONS. At present, surveillance of small renal masses should only be considered in elderly and/or infirm patients with competing health risks, in those with a limited life expectancy, and in those for whom minimal invasive treatment or surgery is not an option. In all other patients, active surveillance should only be considered in the context of a study protocol. Long-term, prospective studies are needed to provide a more accurate assessment of the natural history and metastastic potential of small renal masses.

Focal therapy for kidney cancer: a systematic review

PURPOSE OF REVIEW

Surgical excision remains the standard of care for treatment of localized small renal masses (SRMs). Laparoscopic and percutaneous minimally invasive ablative technologies are being increasingly employed in current urologic practice. We review recent literature regarding focal ablative treatments of SRMs.

RECENT FINDINGS

Most cryoablations are performed using a laparoscopic approach, whereas radiofrequency ablation (RFA) of the SRM is more commonly administered percutaneously. Pretreatment biopsy is performed more often for lesions treated by cryoablation than RFA with a significantly higher rate of indeterminate or unknown pathology for SRMs undergoing RFA versus cryoablation (P < 0.0001). Currently available data suggest that cryoablation results in lower retreatments (P < 0.0001), less local tumor progressions (P < 0.0001) and may be associated with a decreased risk of metastatic progression compared with RFA. It is unclear whether these differences are a function of the technologies or their application. Given the excellent results reported for active surveillance of the SRM in selected patients, the extent to which focal ablation alters the natural history of SRMs has not yet been established.

SUMMARY

Currently, data on the ability of interventions for SRMs to affect the natural history of these masses are lacking. Prospective randomized evaluations of available clinical approaches to SRMs are needed.

Renal tumor natural history: the rationale and role for active surveillance

Renal cell carcinoma (RCC) is the most common malignancy of the kidney. Despite widespread treatment at diagnosis, overall mortality rates associated with RCC have not decreased. Partly because of the more frequent use of abdominal imaging, diagnosis as an incidental finding has increased. The largest increase in incidence is in tumors smaller than 4 cm, termed small renal masses (SRMs). SRMs that are RCC may frequently be growth slowly and have a low risk of early progression. Initial active surveillance with delayed treatment for progression for selected patients should be considered. This should result in an overall decrease in treatment burden and cost saving.

Small renal masses: incidental diagnosis, clinical symptoms, and prognostic factors

Introduction. The small renal masses (SRMs) have increased over the past two decades due to more liberal use of imaging techniques. SRMs have allowed discussions regarding their prognostic, diagnosis, and therapeutic approach. Materials and methods. Clinical presentation, incidental diagnosis, and prognosis factors of SRMs are discussed in this review. Results. SRMs are defined as lesions less than 4 cm in diameter. SRM could be benign, and most malignant SMRs are low stage and low grade. Clinical symptoms like hematuria are very rare, being diagnosed by chance (incidental) in most cases. Size, stage, and grade are still the most consistent prognosis factors in (RCC). An enhanced contrast SRM that grows during active surveillance is clearly malignant, and its aggressive potential increases in those greater than 3 cm. Clear cell carcinoma is the most frequent cellular type of malign SRM. Conclusions. Only some SRMs are benign. The great majority of malign SRMs have good prognosis (low stage and grade, no metastasis) with open or laparoscopic surgical treatment (nephron sparing techniques). Active surveillance is an accepted attitude in selected cases.

A population-based comparison of survival after nephrectomy vs nonsurgical management for small renal masses

OBJECTIVE

To examine population-based rates of cancer-specific and other-cause mortality after either non-surgical management (NSM) or nephrectomy, in patients with small renal masses, as several reports from selected institutions support the applicability of surveillance in patients with small renal masses, but there are no population-based studies confirming the general applicability of this therapy.

PATIENTS AND METHODS

Of 43 143 patients with renal cell carcinoma identified in the 1988-2004 Surveillance, Epidemiology and End Results database, 10 291 had localized small renal masses (<or=4 cm) and were offered NSM (433, 4.2%) or nephrectomy (9858, 95.8%). Univariable matched and multivariable unmatched competing-risks regression models were used in the analyses.

RESULTS

Cumulative incidence plots based on unmatched data, where the effect of other-cause mortality was controlled for, showed a 5.2%, 6.5% and 9.4% survival benefit for nephrectomy vs NSM at 1, 2 and 5 years after nephrectomy or diagnosis, respectively. The same magnitude of the benefit (4.5%, 5.6% and 8.0%) persisted in analyses matched for age, tumour size and year of diagnosis or of nephrectomy. Finally, in multivariable analyses, treatment type, age, tumour size and year of diagnosis or of nephrectomy were independent predictors.

CONCLUSION

Relative to nephrectomy, NSM appears to undermine the overall and cancer-specific survival of patients with small renal masses by as much as 9.4%, at 5 years.

Effect of renal cancer size on the prevalence of metastasis at diagnosis and mortality

PURPOSE

We determined the relationship between the prevalence of metastasis at presentation and cancer specific mortality with tumor size in renal cancer cases using a large cancer database.

MATERIALS AND METHODS

The Surveillance, Epidemiology and End Results data set was analyzed for renal tumors diagnosed from 1998 to 2003. A total of 24,253 patients were included. The prevalence of metastasis and cancer specific survival as a function of tumor size were evaluated using linear and nonlinear curve fitting methods. Metastatic cases with tumors 2.5 cm or less were individually reconfirmed case by case for accuracy.

RESULTS

Increasing tumor size correlated with a higher prevalence of metastasis at diagnosis (range 1.4% for tumors 1 cm or less to 50.9% for tumors greater than 15 cm). Five-year cancer specific mortality in treated patients was also closely related to tumor size (range 3.5% for tumors 1 cm or less to 50.9% for tumors greater than 15 cm). In each instance the relationship was sigmoidal rather than linear and it was best modeled using a quadratic function. The most rapid increase in the prevalence of metastasis and mortality was noted for tumors 4 to 12 cm. In treated patients with tumors 1 cm or less, 1.1 to 2, 2.1 to 3 and 3.1 to 4 the prevalence of metastasis at diagnosis was 1.4%, 2.5%, 4.7% and 7.4%, and the 5-year cancer specific mortality rate was 3.5%, 3.8%, 4.1% and 5.3%, respectively.

CONCLUSIONS

In cases of renal cancer the prevalence of metastasis at presentation and 5-year cancer specific mortality increase in a nonlinear sigmoidal relationship with tumor size.

Observation should be considered as an alternative in management of renal masses in older and comorbid patients

BACKGROUND

Renal masses diagnosed in older and comorbid patients represent a challenge with regard to treatment.

OBJECTIVE

To evaluate clinical outcome and tumor progression in patients with renal masses managed by observation due to age and comorbidity.

DESIGN, SETTING, AND PARTICIPANTS

The medical records of 63 consecutive patients with renal masses primarily managed by observation during 2002-2007 were reviewed retrospectively and analyzed. The mean age for all patients at diagnosis was 76.6 yr, and 59% were male. Mean tumor size was 4.3 cm in diameter at diagnosis. Of these, 30% had Eastern Cooperative Oncology Group performance status (PS) of 2 or 3, 78% were American Society of Anesthesiologists (ASA) class 3, and the patients had a mean of 2.8 other medical conditions.

MEASUREMENTS

Registration of age, ASA class, PS, comorbid conditions, computed tomography scans, primary tumor size, tumor growth rate, pathology parameters, observation time, survival time.

RESULTS AND LIMITATIONS

Five-year overall survival (OS) and cancer-specific survival (CSS) rates were 42.8% and 93.3%, respectively. For tumors < or =4.0 cm in size, 5-yr CSS was 100%. Nine patients received delayed radical treatment, none of whom had later progression of the disease. In 18 patients histopathologic diagnosis of the renal masses were available, and in 15 patients (83%) renal cell carcinoma (RCC) was verified. The annual growth rate was <1cm/yr in 85.4% of the cases. In tumors < or =4.0 cm, only 1 of 27 tumors (3.7%) grew faster than 1cm/yr.

CONCLUSIONS

Management of renal masses by observation among older and comorbid patients seems to give acceptable results with regard to OS and CSS rates after 5 yr. The risk of disease progression is significantly higher in patients with larger sized renal masses (>4 cm). Thus, selection for observation in this group has to be stricter than in a group of patients with smaller sized renal masses (< or =4.0 cm).

Cryoablation or radiofrequency ablation of the small renal mass : a meta-analysis

BACKGROUND

The incidence of renal cell carcinoma is rising because of incidental detection of small renal masses (SRMs). Although surgical resection remains the standard of care, cryoablation and radiofrequency ablation (RFA) have emerged as minimally invasive treatment alternatives. The authors of this report performed a comparative meta-analysis evaluating cryoablation and RFA as primary treatment for SRMs.

METHODS

A search of the MEDLINE database was performed reviewing the world literature for clinically localized renal masses treated by cryoablation or RFA.

RESULTS

Forty-seven studies representing 1375 kidney lesions treated by cryoablation or RFA were analyzed. No differences were detected between ablation modalities with regard to mean patient age (P = .17), tumor size (P = .12), or duration of follow-up (P = .53). Pretreatment biopsy was performed more often for cryoablated lesions (82.3%) than for RFA (62.2%; P < .0001). Unknown pathology occurred at a significantly higher rate for SRMs that underwent RFA (40.4%) versus cryoablation (24.5%; P < .0001). Repeat ablation was performed more often after RFA (8.5% vs 1.3%; P < .0001), and the rates of local tumor progression were significantly higher for RFA (12.9% vs 5.2%; P < .0001) compared with cryoablation. The higher incidence of local tumor progression was found to be correlated significantly with treatment by RFA on univariate analysis (P = .001) and on multivariate regression analysis (P = .003). Metastasis was reported less frequently for cryoablation (1.0%) versus RFA (2.5%; P = .06). Cryoablation usually was performed laparoscopically (65%), whereas 94% of lesions that were treated with RFA were approached percutaneously.

CONCLUSIONS

Ablation of SRMs is a viable strategy based on short-term oncologic outcomes. Although extended oncologic efficacy remains to be established for ablation modalities, the current data suggest that cryoablation results in fewer retreatments and improved local tumor control, and it may be associated with a lower risk of metastatic progression compared with RFA.

Histological characterisation of small renal masses and incidence of silent renal masses

With the introduction of sonographic and CT examinations, the number of small renal masses detected has increased. Benign neoplastic lesions are usually smaller than 4 cm in size, whilst the most common types of renal cell carcinomas have a mean size greater than that, but we must not forget that a significant number of small masses are renal cell carcinomas; even though the rate of benign cases increases as the diameter of the lesions decreases, therefore, size itself cannot be used to rule out a diagnostic of malignancy and often image characteristics are not enough to predict the nature of the lesion with certainty. In this case, histological confirmation must be recommended. Ideally, the histological study must be conducted on the surgical specimen, even though biopsy can be an option in selected cases.

Predicting growth of solid renal masses under active surveillance

OBJECTIVES

The natural history and growth rates of untreated solid enhancing renal tumors is being defined through active surveillance series. Serial radiographic evaluation of patients who are not surgical candidates or refuse surgical treatment provides an opportunity to characterize the growth of untreated enhancing renal tumors. Here we evaluate factors that may help predict radiographic growth during observation.

MATERIALS AND METHODS

We reviewed our renal cancer database for enhancing renal masses that were radiographically observed for a period of at least 12 months. Variables examined included patient age, gender, lesion size on presentation, radiographic tumor characteristics, duration of active surveillance, linear growth rate, surgical pathology, development of new renal tumors, and stage progression.

RESULTS

One hundred nine patients with 124 sporadic enhancing renal tumors were identified undergoing a period of active surveillance of at least 12 months. Median patient age was 73 years (mean 69.8, range 35-87); 72% (78/109) of patients were males. Median duration of active surveillance was 26 months (mean 33.4, range 12-156). Multifocal disease was present in 9% (10/109) of patients on presentation, accounting for 20% (25/124) of all tumors. Tumor size on presentation was a median of 2.0 cm (mean 2.61, range 0.4-12.0). Overall median tumor growth rate was 0.21 cm/y (mean 0.28, range 1.4-2.47). Observed linear growth rates were independent of patient age, gender, tumor size on presentation, multifocality, and radiographic characteristics (solid versus cystic), P > 0.05. Of the patients initiating a period of active surveillance 36% (39/109) eventually underwent definitive therapy. Malignant pathology was present in 90% (35/39) of patients undergoing treatment. In patients continuing active surveillance [64% (70/109)], 2.9% (2/70) developed de novo renal lesions and 1.4% (1/70) developed metastatic disease.

CONCLUSIONS

Currently, no clinical predictors of tumor growth or disease progression have been identified, although, the risk of developing progressive disease over the short term appears low. Clinical and molecular markers of disease progression are needed prior to offering active surveillance to otherwise acceptable surgical candidates.

Outcomes following partial nephrectomy by tumor size

PURPOSE

Pathological evaluation of renal tumors treated with ablative and observational therapy is often limited and renal tumor size may be the only prognostic index available. We established long-term survival in patients following partial nephrectomy according to tumor size.

MATERIALS AND METHODS

A retrospective review of our nephrectomy registry was performed to identify patients who underwent partial nephrectomy for localized (NX/N0/cM0) solid renal tumors 7 cm or less at our institution between 1970 and 2004. Overall, cancer specific, distant metastasis-free and local recurrence-free survival was estimated using the Kaplan-Meier method and stratified according to tumor size in all tumors treated and in patients with pathologically confirmed renal cell carcinoma.

RESULTS

We identified 798 patients who underwent partial nephrectomy for a 7 cm or less renal tumor. Median patient age was 63.5 years and median tumor size was 3.0 cm. Renal cell carcinoma was present in 637 tumors (80%). Overall, cancer specific, metastasis-free and local recurrence-free survival significantly decreased with each 1 cm increase in size in all tumors treated and in those with pathologically confirmed renal cell carcinoma (each p <0.05).

CONCLUSIONS

Partial nephrectomy is associated with durable cancer control in patients with renal tumors 7 cm or less, of which most represent renal cell carcinoma. Tumor size represents a valuable prognostic index in the absence of pathological evaluation of the entire tumor specimen. These results may be used for comparison against outcomes following ablative and observational therapy, for which tumor size is the only prognostic index available.

Diffusion of surgical innovation among patients with kidney cancer

BACKGROUND

Despite their potential benefits to patients with kidney cancer, the adoption of partial nephrectomy and laparoscopy has been gradual and asymmetric. To clarify whether this trend reflects differences in kidney cancer patients or differences in surgeon practice styles, the authors compared the magnitude of surgeon-attributable variance in the use of partial nephrectomy and laparoscopic radical nephrectomy with that attributable to patient and tumor characteristics.

METHODS

By using linked Surveillance, Epidemiology, and End Results-Medicare data, the authors identified a cohort of 5483 Medicare beneficiaries who underwent surgery for kidney cancer between 1997 and 2002. Two primary outcomes were defined: 1) the use of partial nephrectomy and (2) the use of laparoscopy among patients undergoing radical nephrectomy. By using multilevel models, surgeon- and patient-level contributions to observed variations in the use of partial nephrectomy and laparoscopic radical nephrectomy were estimated.

RESULTS

Of the 5483 cases identified, 611 (11.1%) underwent partial nephrectomy (43 performed laparoscopically), and 4872 (88.9%) underwent radical nephrectomy (515 performed laparoscopically). After adjusting for patient demographics, comorbidity, tumor size, and surgeon volume, the surgeon-attributable variance was 18.1% for partial nephrectomy and 37.4% for laparoscopy. For both outcomes, the percentage of total variance attributable to surgeon factors was consistently higher than that attributable to patient characteristics.

CONCLUSIONS

For many patients with kidney cancer, the surgery provided depends more on their surgeon's practice style than on the characteristics of the patient and his or her disease. Consequently, dismantling barriers to surgeon adoption of partial nephrectomy and laparoscopy is an important step toward improving the quality of care for patients with early-stage kidney cancer.

Is Surveillance an Option for the Treatment of Small Renal Masses?

OBJECTIVES

To review the natural history and biological potential of small renal masses in order to evaluate whether surveillance is an option for treatment of small renal masses.

METHODS

Literature search of MEDLINE and additional references from non-MEDLINE-indexed publications concerning surveillance of small renal masses.

RESULTS

Because approximately 26-33% of observed small renal masses do not show radiographic growth, it has been suggested that a brief period of active surveillance may be feasible for selected renal masses, with treatment limited to tumours showing growth. Even though tumour growth might be absent or slow, a proportion of these tumours will express significant malignant behaviour. The biological behaviour of a tumour cannot be unambiguously predicted at present. Surveillance of small renal masses should only be considered in elderly and/or infirm patients with competing health risks, in those with limited life expectancy, and in those for whom surgery is not an option. In all other patients, active surveillance can be considered in the context of a study protocol only. In the majority of the patients, nephron-sparing surgery remains the gold standard treatment.

CONCLUSIONS

Surveillance should only be considered as an alternative to surgery for the treatment of small renal masses in selected patients. It should always be combined with close follow-up imaging and should be allowed only when the patient and the urologist accept the calculated risk. Long-term, prospective studies are needed to provide a more accurate assessment of the natural history and metastastic potential of small renal masses.

Percutaneous Core Biopsy for Renal Masses: Indications, Accuracy and Results

PURPOSE

We evaluated the results, accuracy and clinical incidence of our standard procedure of percutaneous biopsy for solid renal masses.

MATERIALS AND METHODS

From March 1999 to April 2005, 119 percutaneous core biopsies of renal masses were performed. Biopsies were proposed when there was no formal evidence for a carcinoma diagnosis on computerized tomography.

RESULTS

Benign lesions were diagnosed in 24 biopsies (20.1%), including oncocytoma in 13, angiomyolipoma in 5 and chronic pyelonephritis in 5. Malignancy was identified in 70 biopsies (58.8%), including 57 renal carcinomas (conventional renal cell in 41, papillary in 12 and chromophobe in 4), 4 transitional cell carcinomas, 8 metastases and 1 lymphoma. For 25 biopsies (21%) no accurate diagnosis was possible, including 12 that showed inflammatory tissue and 13 with normal or necrotic tissue. These inconclusive biopsies prompted repeat biopsy in 13 patients, in whom a total of 11 malignant lesions were diagnosed. A total of 64 nephrectomies were performed with a biopsy accuracy for histopathological tumor type and Fuhrman nuclear grade of 86% and 46%, respectively. A period of watchful waiting was proposed for 31 patients (34.2%) and no renal malignancies were found. Computerized tomography showed stabilization or disappearance of the initial renal mass.

CONCLUSIONS

Percutaneous renal tumor biopsies are safe, cost-effective and often conclusive for an acute histological diagnosis. This procedure could be decisive for choosing the optimal treatment, particularly to avoid nephrectomy for benign lesions. Biopsies should not be considered a routine procedure but they could be indicated when there is a lack of radiological evidence in elective patients.

Der kleine, zufällig entdeckte Nierentumor

Tumor size is a prognostic marker and correlates to survival after surgical therapy. Of 287 patients with small (<or=4 cm) renal tumors, 19.5% had a benign lesion and thus harmless. All others were renal cell cancers; 4.9% of tumors were detected because of metastases and consecutively treated. Tumors with a diameter <or=3 cm showed a tumor stage >or=pT3a in 10.9%, a high Fuhrman grade >or=3, multifocality in 8.5%, and metastases in 2.4%. Tumors with a diameter of 3.1-4 cm showed dramatically more aggressive parameters; 35.7% had stage >or=pT3a, 25.5% Fuhrman grade >or=G3, and 8.4% metastases (M+). However, evaluation of the tumor diameter on CT has an error of about +/-0.3 cm, which will lead to an even more pronounced error in volume determination. Therefore, determination of growth in follow-up imaging is unreliable. With the exception of the typical angiomyolipoma, determination of dignity for small solid kidney lesions is unreliable even with modern imaging. Only 17% of 80 benign lesions in our series were assessed as benign on preoperative CT. Thus, preoperative evaluation not only based on imaging seems to be valuable, especially in patients with higher surgical risk. Percutaneous renal mass biopsy has an accuracy of over 90% for detecting benign lesions and can influence therapeutic decisions, especially in patients with higher surgical risk.

Allelic loss on chromosomes 8 and 9 correlates with clinical outcome in locally advanced clear cell carcinoma of the kidney

PURPOSE

We correlated allelic loss on chromosomes 8p, 9p and 14q with clinical outcome in locally advanced conventional renal cell carcinoma.

MATERIALS AND METHODS

We analyzed radical nephrectomy specimens from 72 stage P3N0 conventional renal cell carcinomas by microsatellite loss of heterozygosity (LOH) analyses directed at chromosomes 3p, 8p, 9p and 14q (2 primers per chromosome). All patients were treated with surgery only. LOH results were correlated with disease-free survival using the Kaplan-Meier method.

RESULTS

We detected LOH on chromosome 3p in 60 of 64 (94%), on chromosome 8p in 19 of 59 (32%), on 9p in 21 of 67 (31%) and on 14q in 18 of 70 (26%) informative cases. Of the 72 patients 24 (33%) had recurrence during followup. On univariate analysis patients with tumors demonstrating LOH on chromosomes 8p and 9q were at high risk for recurrence (p = 0.01). The correlation of recurrence with LOH approached significance for the individual chromosomes 8p and 9p (p = 0.10 and 0.14, respectively). No correlation was observed of LOH on chromosome 14q with recurrence (p = 0.42). The correlation of tumor grade with risk of relapse also approached significance (p = 0.12). On multivariate analysis LOH on chromosome 8p was a more powerful predictor of recurrence than tumor grade. When combinations of LOH on chromosomes were tested, LOH on chromosomes 8p and 9p was the most powerful predictor of recurrence (p = 0.006).

CONCLUSIONS

LOH on chromosomes 8p or 9p may provide prognostic significance in patients with locally advanced renal cell carcinoma.