Active Surveillance for Larger (cT1bN0M0 and cT2N0M0) Renal Cortical Neoplasms

Intermediate- and long-term oncological outcomes of active surveillance for localized renal masses: a systematic review and quantitative analysis

OBJECTIVE

To evaluate intermediate- and long-term oncological outcomes of active surveillance (AS) for localized renal masses (LRMs).

METHODS

This systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement and registered on PROSPERO (CRD42021230416). Studies on AS for LRMs with at least 3 years' follow-up were eligible. Two review authors independently screened the literature, extracted data, and assessed risk of bias. The primary outcomes were metastasis rate, renal cell carcinoma (RCC)-specific mortality (RCC-SM) and all-cause mortality (ACM). Pooled estimates were obtained from random-effects models. Subgroup analyses were performed for small renal masses (SRMs; ≤4 cm) and non-SRMs (>4 cm).

RESULTS

We analysed 18 unique cohorts comprising 2066 patients. The pooled initial maximum tumour size was 2.8 cm (95% confidence interval [CI] 2.7-3.0) and the percutaneous biopsy rate was 28%. The pooled mean annual growth rate was 2.8 mm (95% CI 2.1-3.4). Within a pooled mean follow-up of 53 months, 2.1% (95% CI 1.0-3.6) of patients developed metastatic disease, 1.0% (95% CI 0.3-2.1) died from RCC and 22.6% (95% CI 15.8-30.2) died from any cause. For patients with SRMs (nine studies, n = 987), the pooled metastasis rate was 1.8% (95% CI 0.5-3.7), RCC-SM was 0.6% (95% CI 0-2.1), and ACM was 28.5% (95% CI 17.4-41.4). Across five studies reporting on outcomes of 239 patients with non-SRMs, the pooled metastasis rate was 5.1% (95% CI 0-17.3), RCC-SM was 2.1% (95% CI 0-8.9) and ACM was 29.1% (95% CI 13.6-47.3). This review is limited by non-standardized inclusion criteria, definitions and follow-up, data heterogeneity, limited patient numbers in sub-analyses and absence of high-quality studies.

CONCLUSIONS

Active surveillance is a safe intermediate- and long-term management option for well-selected patients with LRMs, especially those with SRMs. Limited data are available for non-SRMs, but current evidence would support further evaluation of this approach in selected patients. It is not possible to draw definitive conclusions until more high-quality data become available.

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.

Urologic oncology practice during COVID-19 pandemic: A systematic review on what can be deferrable vs. nondeferrable

PURPOSE

To provide a review of high-risk urologic cancers and the feasibility of delaying surgery without impacting oncologic or mortality outcomes.

MATERIALS AND METHODS

A thorough literature review was performed using PubMed and Google Scholar to identify articles pertaining to surgical delay and genitourinary oncology. We reviewed all relevant articles pertaining to kidney, upper tract urothelial cell, bladder, prostate, penile, and testicular cancer in regard to diagnostic, surgical, or treatment delay.

RESULTS

The majority of urologic cancers rely on surgery as primary treatment. Treatment of unfavorable intermediate or high-risk prostate cancer, can likely be delayed for 3 to 6 months without affecting oncologic outcomes. Muscle-invasive bladder cancer and testicular cancer can be treated initially with chemotherapy. Surgical management of T3 renal masses, high-grade upper tract urothelial carcinoma, and penile cancer should not be delayed.

CONCLUSION

The majority of urologic oncologic surgeries can be safely deferred without impacting long-term cancer specific or overall survival. Notable exceptions are muscle-invasive bladder cancer, high-grade upper tract urothelial cell, large renal masses, testicular and penile cancer. Joint decision making among providers and patients should be encouraged. Clinicians must manage emotional anxiety and stress when decisions around treatment delays are necessary as a result of a pandemic.

Age Is Important for the Early-Stage Detection of Breast Cancer on Both Transcriptomic and Methylomic Biomarkers

Patients at different ages have different rates of cell development and metabolisms. As a result, age should be an essential part of how a disease diagnosis model is trained and optimized. Unfortunately, most of the existing studies have not taken age into account. This study demonstrated that disease diagnosis models could be improved by merely applying individual models for patients of different age groups. Both transcriptomes and methylomes of the TCGA breast cancer dataset (TCGA-BRCA) were utilized for the analysis procedure of feature selection and classification. Our experimental data strongly suggested that disease diagnosis modeling should integrate patient age into the whole experimental design.

Growth rates and outcomes of observed large renal masses

INTRODUCTION

The natural history of small renal masses has been well defined, leading to the recommendation of active surveillance in some patients with limited life expectancy. However, this information is less clear for large renal masses (LRM), leading to ambiguity for management in the older, comorbid patient. The objective of this study was to define the natural history, including the growth rate and metastatic risk, of LRM in order to better counsel patients regarding active surveillance.

METHODS

This was a retrospective review of patients with solid renal masses >4 cm that had repeated imaging identified from an institutional imaging database. Patient comorbidities and outcomes were obtained through retrospective chart analysis. Outcomes assessed included tumour growth and metastatic rates, as well as cancer-specific (CSS) and overall survival (OS) usimg Kaplan-Meier methodology.

RESULTS

We identified 69 patients between 2005 and 2016 who met the inclusion criteria. Mean age at study entry was 75.5 years; mean tumour maximal dimension at study entry was 5.6 cm. CSS was 83% and OS 63% for patients presenting without metastasis, with a mean followup of 57.5 months. The mean growth rate of those that developed metastasis during followup (n=15) was 0.98 cm/year (95% confidence interval [CI] 0.33-1.63) as compared to those that did not develop metastasis (n=46), with a growth rate of 0.67 cm/year (95% CI 0.34-1) (non-significant). Seven patients had evidence of metastasis at the baseline imaging of their LRM and had subsequent growth rate of 1.47 cm/year (95% CI 0.37-2.57) (non-significant) CONCLUSIONS: Compared to small renal masses, LRM are associated with higher metastasis rates and lower CSS and more rapid growth rates. Selection criteria for recommending observation of LRM in older, comorbid patients should be more conservative than for small renal masses.

The natural history of large renal masses followed on observation

PURPOSE

The safety and feasibility of active surveillance in comorbid patients with renal masses ≥4.0cm is uncertain. The aim of this study is to describe our institutional experience with the observation of large renal masses.

MATERIALS AND METHODS

One hundred patients were identified with renal masses ≥ 4.0cm that were followed on observation for at least 6 months without surgical intervention between 1994 and 2016. Linear regression was conducted to determine predictors for renal mass growth and competing risk methods were used to estimate the probability of progression in the setting of death from other causes.

RESULTS

Median age at diagnosis was 73 years and 73% of patients had a Charlson Comorbidity index ≥ 4. At presentation, the median mass size was 4.9cm. The median growth rate was 0.4cm/y and there were no significant predictors of growth. Surveillance was discontinued in 34 patients who underwent delayed intervention. Median follow up for metastasis-free survivors was 4 years. In total, 10 patients developed metastatic disease, 3 died from kidney cancer and 30 patients died from other causes. The 5-year probability of other cause mortality was 22% (95% CI: 14%-32%) compared to 6% (95% CI: 2%-13%) for metastatic progression of kidney cancer.

CONCLUSION

In highly comorbid patients, the observation of large renal masses has low likelihood for metastatic progression relative to the risk of nonkidney cancer related death. This data supports the use of surveillance as an acceptable strategy for highly selected patients with competing risks from other serious illnesses.

Renal cancer at unenhanced CT: imaging features, detection rates, and outcomes

PURPOSE

To describe and quantify the rate of detection of renal cancer on unenhanced CT.

METHODS

This retrospective, HIPAA-compliant study was approved by the Institutional Review Board. Electronic health records for all patients who underwent unenhanced abdominal CT at our institution between 2000 and 2005 were reviewed to identify patients subsequently diagnosed with renal cancer during a follow-up period of up to 12 years. Images were reviewed to determine if the cancer was visible at index (first) unenhanced CT and their findings recorded. Original radiology reports were reviewed to determine whether the renal cancer was reported; Fisher's Exact Test compared imaging features of detected and missed cancers. Clinical outcomes including time until diagnosis and stage at diagnosis were used to assess the potential impact of missed cancers.

RESULTS

Of 15,695 patients, 82 (0.52%) were diagnosed with renal cancer. Of these, 43/82 (52%) cancers were retrospectively detectable on index unenhanced CT. Among retrospectively detectable cancers, 63% (27/43) were originally detected and reported on index CT and 37% (16/43) were missed. Size was the only feature associated with detection; 83% (20/24) of cancers > 3.0 cm were detected versus 37% (7/19) of cancers ≤ 3.0 cm (p = 0.0036). Although none of the 16 missed renal cancers developed metastases between index CT and time of diagnosis (median 33.5 months), 4 (25%) progressed in stage.

CONCLUSIONS

Renal cancer was rare in patients undergoing unenhanced abdominal CT. Over one-third of potentially detectable cancers were missed prospectively. However, missed cancers did not metastasize and infrequently progressed in stage before being diagnosed.

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.

Collaborative Review of Risk Benefit Trade-offs Between Partial and Radical Nephrectomy in the Management of Anatomically Complex Renal Masses

BACKGROUND

While partial nephrectomy (PN) is the recommended treatment for many small renal masses, anatomically complex tumors necessitate a clear understanding of the potential risks and benefits of PN and radical nephrectomy (RN).

OBJECTIVE

To critically review the comparative effectiveness evidence of PN versus RN; to describe key trade-offs involved in this treatment decision; and to highlight gaps in the current literature.

EVIDENCE ACQUISITION

A collaborative critical review of the medical literature was conducted.

EVIDENCE SYNTHESIS

Patients who undergo PN for an anatomically complex or large mass may be exposed to perioperative and potential oncologic risks that could be avoided if RN were performed, while patients who undergo RN may forgo long-term benefits of renal preservation. Decision-making regarding the optimal treatment with PN or RN among patients with anatomically complex or large renal mass is highly nuanced and must balance the risks and benefits of each approach. Currently, high-quality evidence on comparative effectiveness is sparse. Retrospective comparisons are plagued by selection biases, while the one existing prospective randomized trial, albeit imperfect, suggests that nephron-sparing surgery may not benefit all patients.

CONCLUSIONS

For anatomically complex tumors, PN preserves renal parenchyma but may expose patients to higher perioperative risks than RN. The risks and benefits of each surgical approach must be better objectified for identification of patients most suitable for complex PN. A prospective randomized trial is warranted and would help in directing patient counseling.

PATIENT SUMMARY

Treatment decisions for complex renal masses require shared decision-making regarding the risk trade-offs between partial and radical nephrectomy.

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.

Cystic renal masses

PURPOSE

The purpose of the study is to provide an update on the imaging evaluation of cystic renal masses, to review benign and malignant etiologies of cystic renal masses, and to review current controversies and future directions in the management of these lesions.

CONCLUSIONS

Cystic renal masses are relatively common in daily practice. The Bosniak classification is a time-proven method for the imaging classification and management of these lesions. Knowledge of the pathognomonic features of certain benign Bosniak 2F/3 lesions is important to avoid surgery on these lesions (e.g., localized cystic disease, renal abscess). For traditionally surgical Bosniak lesions (Classes 3 and 4), there are evolving data that risk stratification based on patient demographics, imaging size, and appearance may allow for expanded management options including tailored surveillance or ablation, along with the traditional surgical approach.

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.

The growth rate of "clinically significant" renal cancer

Surveillance studies of enhancing renal masses report on a mean tumor growth rate of about 0.3 cm/year. In most of these studies however, only small tumors in elderly patients were followed. In the current report, we attempt to evaluate the growth rate of “clinically significant” renal carcinomas defined as tumors that were treated immediately upon diagnosis. 46 patients (mean age 64 years SD 11 years) were treated for renal carcinoma. All had a cross-sectional imaging studies performed 6–60 months prior to diagnosis of kidney cancer demonstrating no tumor. Tumor growth rate was calculated by dividing tumor’s largest diameter by the time interval between the normal kidney imaging and diagnosis of renal cancer. Mean tumor diameter was 4.5 cm (SD 2.4 cm). Mean time period from the normal imaging to diagnosis of renal cancer was 33.6 months (SD 18 months). According to the proposed model, the average growth rate of “clinically significant” renal carcinomas was 2.13 cm/year (SD 1.45, range 0.2–6.5 cm/year). Tumor growth rate correlated inversely with patient’s age (p = 0.007). Patient gender or Fuhrman’s grade did not correlate however. The growth rate of “clinically significant” renal cancer appears to be higher than the rate reported in surveillance trials. Renal tumors tend to grow faster in young patients. As such, variable growth rate should be taken into account when considering active surveillance in young patients and when designing trials for evaluation of anti-cancer agents.

Growth kinetics and short-term outcomes of cT1b and cT2 renal masses under active surveillance

PURPOSE

Compared to T1a lesions the natural history of untreated renal masses larger than 4 cm is poorly understood. We assessed the growth kinetics and outcomes of cT1b/T2 cortical renal tumors managed by an initial period of active surveillance. We compared these cases to those treated with definitive delayed intervention.

MATERIALS AND METHODS

We reviewed our institutional, prospectively maintained renal tumor database to identify enhancing solid and cystic masses managed expectantly. Included in analysis were clinically localized tumors greater than 4.0 cm (T1b or greater) that were radiographically followed for more than 6 months. Tumor size at presentation, annual linear tumor growth rate, Charlson comorbidity index, followup and clinical outcomes were compared in patients who remained on active surveillance and those who underwent delayed surgical intervention.

RESULTS

We identified 72 tumors 4 cm or greater in diameter in a total of 68 patients. Active surveillance was the only treatment in 45 patients (66%) while 23 (34%) progressed to intervention. Median tumor size at presentation was 4.9 cm and the mean linear growth rate was 0.44 cm per year. Of the masses 14.7% demonstrated no growth with time. Comparing patients treated exclusively with active surveillance and those who progressed to definitive intervention revealed no difference in median tumor size at presentation (4.9 vs 4.6 cm, p = 0.79) or the median Charlson comorbidity index (3 vs 2, p = 0.6) but significant differences were seen in median age at presentation (77 vs 60 years, p = 0.0002) and the mean linear growth rate (0.37 vs 0.73 cm per year, p = 0.02). After adjustment younger patients (OR 0.91, 95% CI 0.86-0.97) and tumors with a faster linear growth rate (OR 9.1, 95% CI 1.7-47.8) were more likely to be treated with delayed surgical intervention. At a mean ± SD 38.9 ± 24.0 months of followup (median 32, range 6 to 105) 9 patients (13%) had died of another cause and none had progressed to metastatic disease.

CONCLUSIONS

Localized cT1b or larger renal masses show growth rates comparable to those of small tumors managed expectantly with a low rate of progression to metastatic disease at short-term followup. An initial period of active surveillance to determine tumor growth kinetics is a reasonable option in select patients with significant competing risks and limited life expectancy.

[Active surveillance: concept for renal cell carcinoma?]

More than 80% of renal cell carcinomas are currently being detected incidentally by ultrasonic imaging and often affect elderly patients with substantial comorbidities. Surgical options cannot be applied in this cohort as routinely as in younger patients, as in some cases the perioperative risk factors may outweigh the risk of tumor-related death. In this context the concept of active surveillance for localized renal cell cancer in elderly patients is becoming increasingly important. The aim of active surveillance is to avoid surgery-related adverse effects and to achieve a controlled observation of tumor behavior with an option of delayed intervention in cases of aggressive clinical tumor features. This review sheds light on the current status of this strategy.

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.

Enhancing renal tumors in patients with prior normal abdominal imaging: further insight into the natural history of renal cell carcinoma

PURPOSE

Patients undergoing serial cross-sectional abdominal imaging to evaluate abdominal symptomatology may have a renal tumor develop during followup of an unrelated disease process. Evaluation of such patients provides an opportunity to further define the radiographic inception, natural history and growth patterns of renal tumors.

MATERIALS AND METHODS

Renal tumor databases from 2 institutions were reviewed for patients in whom an enhancing renal tumor developed despite a prior normal cross-sectional radiographic examination of the kidneys. Variables evaluated included age, gender, tumor size at presentation, calculated tumor growth rate from negative scan to radiographic presentation and pathology in patients undergoing definitive treatment.

RESULTS

We identified 36 patients with an average age of 65 years (range 44 to 82). Mean tumor size on presentation was 2.3 cm (range 1.0 to 5.0). The presumed absolute growth rate based on the timing of the initial negative imaging study and tumor diameter at presentation was significantly greater than the observed absolute growth rate after tumor detection (0.71 vs 0.039 cm per year, p = 0.028). No difference was noted between presumed and observed tumor growth based on absolute change in tumor volume (1.44 vs 5.37 cm(3) per year, p = 0.203). Presumed relative growth rates based on tumor diameter (665% vs 23% per year) and volume (1,397% vs 169% per year) were significantly greater than observed relative growth rates (p = 0.005 and p = 0.013, respectively).

CONCLUSIONS

The presumed growth rate of the tumors was significantly greater than the observed growth rate, suggesting that tumor growth rates do not follow a linear pattern throughout their development and progression.

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.

Small renal masses progressing to metastases under active surveillance: a systematic review and pooled analysis

BACKGROUND

The authors systematically reviewed the literature and conducted a pooled analysis of studies on small renal masses who underwent active surveillance to identify the risk progression and the characteristics associated with metastases.

METHODS

A search of the MEDLINE database was performed to identify all clinical series that reported the surveillance of localized renal masses. For studies that reported individual-level data, clinical and radiographic characteristics of tumors without progression were compared with the characteristics of tumors that progressed to metastases.

RESULTS

Eighteen series (880 patients, 936 masses) met screening criteria; and, among these, 18 patients were identified who had tumors that progressed to metastasis (mean, 40.2 months). Six studies (259 patients, 284 masses) provided individual-level data for pooled analysis. At a mean (± standard deviation) follow-up of 33.5 ± 22.6 months, the mean initial greatest tumor dimension was 2.3 ± 1.3 cm, and mean linear growth rate was 0.31 ± 0.38 cm per year. Sixty-five masses (23%) exhibited zero net growth under surveillance, and none of those masses progressed to metastasis. A pooled analysis revealed increased age (age 75.1 ± 9.1 years vs 66.6 ± 12.3 years; P = .03), an initial greatest tumor dimension (4.1 ± 2.1 cm vs 2.3 ± 1.3 cm; P < .0001), initial estimated tumor volume (66.3 ± 100.0 cm(3) vs 15.1 ± 60.3 cm(3) ; p = .0001), linear growth rate of (0.8 ± 0.65 cm per year vs 0.3 ± 0.4 cm per year; P = .0001), and a volumetric growth rate of 27.1 ± 24.9 cm(3) per year (vs 6.2 ± 27.5 cm(3) per year; P < .0001) in the progression cohort.

CONCLUSIONS

A substantial proportion of small renal masses remained radiographically static after an initial period of active surveillance. Progression to metastases occurred in a small percentage of patients and generally was a late event. The current results indicated that, in patients who have competing health risks, radiographic surveillance may be an acceptable initial approach, and delayed intervention may be reserved for patients who have tumors that exhibit significant linear or volumetric growth.

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.

Growth kinetics of renal masses: analysis of a prospective cohort of patients undergoing active surveillance

BACKGROUND

Active surveillance (AS) represents a treatment option for renal masses in patients who are not surgical candidates either because of existing comorbidities or patient choice. Among renal masses undergoing AS, some grow rapidly and require treatment or progress to metastatic disease. Patient and tumour characteristics related to this more aggressive behaviour have been poorly studied.

OBJECTIVE

To report the analysis of a multi-institutional cohort of patients undergoing AS for small renal masses.

DESIGN, SETTING, AND PARTICIPANTS

This prospective study included 82 patients with 84 renal masses who underwent AS in three Canadian institutions between July 2001 and June 2009.

INTERVENTION

All patients underwent AS for renal masses presumed to be renal cell carcinoma (RCC) as based on diagnostic imaging.

MEASUREMENTS

Age, sex, symptoms at presentation, maximum diameter at diagnosis (cm), tumour location (central/peripheral), degree of endophytic component (1-100%), and tumour consistency (solid/cystic) were used to develop a predictive model of the tumour growth rate using binary recursive partitioning analysis with a repeated measures outcome.

RESULTS AND LIMITATIONS

With a median follow-up of 36 mo (range: 6-96), the mean annual renal mass growth rate for the entire cohort was 0.25 cm/yr (standard deviation [SD]: 0.49 cm/yr). Only one patient (1.2%) developed metastatic RCC. Amongst all variables, maximum diameter at diagnosis was the only predictor of tumour growth rate, and two distinct growth rates were identified. Masses that are ≥2.45 cm in largest diameter at diagnosis grow faster than smaller masses. This series was limited by its moderate sample size, although it is the largest published prospective series to date.

CONCLUSIONS

We confirm that most renal masses grow slowly and carry a low metastatic potential. Tumour size is a predictor of tumour growth rate, with renal masses <2.45 cm growing more slowly than masses >2.45 cm.