The natural history of untreated renal masses

RESIRT: A Phase 1 Study of Selective Internal Radiation Therapy Using Yttrium-90 Resin Microspheres in Patients With Primary Renal Cell Carcinoma

INTRODUCTION

Selective internal radiation therapy (SIRT) is a potential treatment of primary renal cell carcinoma (RCC) deemed unsuitable for conventional therapy. RESIRT is the first-in-human study to evaluate safety and feasibility of SIRT for primary RCC.

PATIENTS AND METHODS

Patients with RCC, unsuitable for, or who declined conventional therapy, were eligible. A single transfemoral micro-catheter administration of yttrium-90 (Y-90) resin microspheres (SIR-Spheres) was delivered super selectively via the renal artery to the tumour at intended radiation doses of 75, 100, 150, 200, 300 Gy and a final cohort with a procedural endpoint of "imminent stasis," in a dose-escalation design. Post-SIRT follow-up was 12 months. Study endpoints included safety and toxicity 30-days and 12-months post-SIRT and tumour response (RECIST v1.1).

RESULTS

In total, 21 patients were enrolled, mean (SD) age was 75 (9.3) years, WHO performance status was 0 in 81%, 12 (57%) had stage 3 chronic kidney disease, and 7 (33%) had prior contralateral nephrectomy. Overall, 71% of patients completed 12 months of follow-up. Intended doses were delivered without any dose-limiting toxicity. Seventeen out of 21 (81%) patients experienced an adverse event (AE) from any cause within 30 days post-SIRT; all SIRT-related AEs were grade 1 to 2. Best overall tumour responses were partial response 1/21 (4.8%), stable disease 19/21 (90.5%) and progressive disease 1/21 (4.8%).

CONCLUSION

This study demonstrated good tolerability of SIRT at all dose levels including "imminent stasis" in treating primary tumours in RCC patients otherwise unsuitable for conventional therapy. SIRT with Y-90 resin microspheres may be a feasible treatment option for RCC.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN, SETTING, AND PARTICIPANTS

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

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

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

RESULTS AND LIMITATIONS

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

CONCLUSIONS

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

PATIENT SUMMARY

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

Management of Small Renal Masses

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

Active Surveillance for Small Renal Masses: When Less is More

CONTEXT

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

OBJECTIVE

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

PATIENT SUMMARY

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

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

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

Non-Surgical Ablative Therapy for Management of Small Renal Masses-Current Status and Future Trends

A large number of small renal masses (SRMs) with size less than 4 cm are being identified due to advances in diagnostic imaging. As the natural history of these tumours remains unknown, there is no reliable way to predict their behaviour or future growth. Although, partial nephrectomy is the gold standard for treatment of these tumours, ablative non-surgical therapies such as cryoablation and radiofrequency ablation provide a less invasive option of treatment with comparable oncological outcomes. In this systematic review, the principle, indications, methods of treatment, oncological control, complication and renal function of ablative therapies are critically reviewed. Cryotherapy utilizes the principle of inducing tissue destruction by freezing and thawing using argon and helium gasses, respectively. Radiofrequency ablation (RFA) works on the principle of tissue heating. Ablative treatments are particularly useful in the elderly patients, those with comorbidities or in patients with SRMs in solitary kidneys or renal impairment. Ablative therapies have less procedure-related complications and have promising medium-term oncological outcome. Longer-term results are accumulating. Cryotherapy may be a better modality for oncological control than RFA. Ablative therapy has emerged as a viable treatment options for SRMs with recurrence free survival rates approaching that of extirpative surgery. However, there is no consensus in the literature on the best selection criteria and this needs further refinement. Prospective long-term data with regards to oncological control is still needed.

Significance of chromosome 9p status in renal cell carcinoma: a systematic review and quality of the reported studies

Defining the prognosis of renal cell carcinoma (RCC) using genetic tests is an evolving area. The prognostic significance of 9p status in RCC, although described in the literature, remains underutilised in clinical practice. The study explored the causes of this translational gap. A systematic review on the significance of 9p status in RCC was performed to assess its clinical applicability and impact on clinical decision-making. Medline, Embase, and other electronic searches were made for studies reporting on 9p status in RCC. We collected data on: genetic techniques, pathological parameters, clinical outcomes, and completeness of follow-up assessment. Eleven studies reporting on 1,431 patients using different genetic techniques were included. The most commonly used genetic technique for the assessment of 9p status in RCC was fluorescence in situ hybridization. Combined genomic hybridisation (CGH), microsatellite analysis, karyotyping, and sequencing were other reported techniques. Various thresholds and cut-off values were used for the diagnosis of 9p deletion in different studies. Standardization, interobserver agreement, and consensus on the interpretation of test remained poor. The studies lacked validation and had high risk of bias and poor clinical applicability as assessed by two independent reviewers using a modified quality assessment tool. Further protocol driven studies with standardised methodology including use of appropriate positive and negative controls, assessment of interobserver variations, and evidenced based follow-up protocols are needed to clarify the role of 9p status in predicting oncological outcomes in renal cell cancer.

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.

Factors affecting survival in 267 consecutive patients undergoing surgery for spinal metastasis from renal cell carcinoma

OBJECT

Renal cell carcinoma (RCC) frequently metastasizes to the spine, and the prognosis can be quite variable. Surgical removal of the tumor with spinal reconstruction has been a mainstay of palliative treatment. The ability to predict prognosis is valuable when determining the role and magnitude of surgical intervention in cancer patients. To better identify factors affecting survival in patients undergoing surgery for spinal metastasis from RCC, the authors undertook a retrospective analysis of a large patient cohort at a tertiary care cancer center.

METHODS

Relevant clinical data on a consecutive series of patients who had undergone surgery for spinal metastasis of RCC between 1993 and 2007 at The University of Texas MD Anderson Cancer Center were retrospectively reviewed. Demographic data, histopathological grade of primary tumor, timing of spinal surgery relative to diagnosis, treatment history prior to surgery, neurological status, and systemic disease burden were analyzed to determine the impact of these factors on survival outcome.

RESULTS

The authors identified 267 patients who met the study criteria. Five-year overall survival (OS) after spine tumor resection was 7.8%, with a median OS of 11.3 months (95% CI 9.5-13.0 months). Patients with Fuhrman Grade 4 RCC had a median OS of 6.1 months (95% CI 3.5-8.7 months), which was significantly lower than the 14.3 months (95% CI 9.1-19.4 months) observed in patients with Fuhrman Grade 3 or less RCC (p < 0.001). Patients with preoperative neurological deficits had a median survival of 5.9 months (95% CI 4.1-7.7 months), which was significantly lower than the 13.5 months (95% CI 10.4-16.6 months) observed in patients with a normal neurological examination (p < 0.001). Patients whose spine was the only site of metastasis had a median OS of 19 months (95% CI 9.8-28.2 months) after surgery, significantly longer than the 9.7 months (95% CI 8.1-11.3 months) observed in patients with additional extraspinal metastasis sites (p < 0.001). Patients with nonprogressing extraspinal metastasis (no metastasis, stable, or concurrent) had a median survival of 20.6 months (95% CI 15.1-26.1 months), compared with 5.6 months (95% CI 4.4-6.8 months) in patients with progressing metastasis (p < 0.001).

CONCLUSIONS

The authors identified several factors influencing survival after spine surgery for metastatic spinal RCC, including grade of the original nephrectomy specimen, activity of the systemic disease, and neurological status at the time of surgery. These clinical features may help to identify patients who may benefit from aggressive surgical intervention.

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.

Prevention and handling of complications of renal focal therapies

Small renal lesions often confer relatively low oncologic risk and, as such, dictate for treatment strategies with low morbidity. Minimally invasive ablative techniques have been developed and can deliver good outcomes where used judiciously. The potential risks of treatment relate to the method of ablation, the route by which it is delivered, together with patient and tumor factors. The complications associated with radiofrequency ablation and cryoablation, delivered via percutaneous and laparoscopic approaches, are considered in this review. Percutaneous ablation appears to be associated with lower rates of morbidity but higher rates of recurrence when compared with laparoscopic ablation. The ability to dissect the lesion away from surrounding structures is limited with the percutaneous approach, which can lead to poor outcomes when treating lesions close to the ureter or hilum. Hemorrhagic complications that are seen with laparoscopic cryoablation are most often associated with tumor fracture during the freeze-thaw cycle. This is encountered most frequently in larger, peripheral lesions but may be mitigated by slowing the freeze rate. Postablation inpatient stays are often short, and early signs of complication are often nonspecific. This combination can lead to significant delay in the recognition of postablative problems with a resultant increase in morbidity. A high index of suspicion together with appropriate use of imaging allows for earlier detection and management of complications.

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.

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.

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.

Prognostic variables to predict cancer-related death in incidental renal tumours

OBJECTIVE

To identify, in a large multicentre series of incidental renal tumours, the key factors that could predict cancer-related deaths, as such tumours have a better outcome than symptomatic tumours and selected patients are increasingly being included in watchful-waiting protocols.

PATIENTS AND METHODS

Data from 3912 patients were extracted from three international kidney-cancer databases. Age, gender, Eastern Cooperative Oncology Group (ECOG) performance status (PS), Tumour-Node-Metastasis (TNM) stage, tumour size, Fuhrman grade, and final pathology were recorded. Benign tumours and malignant lesions with incomplete information were excluded from final analysis.

RESULTS

The mean (SD) age of the patients was 60.6 (12.2) years and the mean tumour size 5.5 (3.5) cm. Most tumours were malignant (90.2%) and of low stage (T1-T2, 71.7%) and low grade (G1-G2, 72.4%). There were nodal and distant metastases in 5.7% and 13% of the patients. In all, 525 (14.4%) patients died from cancer; in this group, tumours were >4 cm in 88.2% and had nodal or distant metastases in 20.2% and 49.3%, respectively. Multivariable analysis showed that tumour size >4 cm, ECOG PS >or=1, TNM stage and Fuhrman grade were independent predictors of cancer-related death.

CONCLUSION

A significant proportion of incidental renal tumours can lead to the death of the patient. Standard prognostic variables for renal cell carcinoma appear to remain valid for this subset of patients. A watchful-waiting strategy should not be recommended if the tumour diameter is >4 cm, if biopsy confirms high-grade tumours, or if there is an impaired ECOG PS, or computed tomography findings suggest the presence of advanced T stage.