Determinants of Active Surveillance in Patients With Small Renal Masses

Urologist-level variation in the management of T1a renal cell carcinoma: A population-based cohort study

OBJECTIVES

Lack of strict indications in current guidelines have led to significant variation in management patterns of small renal masses. The impact of the urologist on the management approach for patients with small renal masses has not been explored previously.

MATERIALS AND METHODS

Using the linked Surveillance, Epidemiology, and End Results-Medicare database, patients aged ≥66 years diagnosed with small renal masses from January 1, 2004 to December 31, 2013 were identified and assigned to primary urologists. Mixed-effects logistic models were used to evaluate factors associated with different management approaches, estimate urologist-level probabilities of each approach, assess management variation, and determine urologist impact on choice of approach.

RESULTS

A total of 12,402 patients with 2,794 corresponding primary urologists were included in the study. At the individual urologist level, the estimated case-adjusted probability of different approaches varied markedly: nonsurgical management (mean, 12.8%; range, 4.9%-36.1%); thermal ablation (mean, 10.8%; range, 2.4%-66.3%); partial nephrectomy (mean, 30.1%; range, 10.1%-66.6%); and radical nephrectomy (mean, 40.4%; range, 17.7%-71.6%). Compared to patient and tumor characteristics, the primary urologist was a more influential measured factor, accounting for 13.6% (vs. 12.9%), 33.8% (vs. 2.1%), 15.1% (vs. 8.4%), and 13.5% (vs. 4.0%) of the variation in management choice for nonsurgical management, thermal ablation, partial nephrectomy, and radical nephrectomy, respectively.

CONCLUSIONS

Significant variation exists in the management of small renal masses and appears to be driven primarily by urologist preference and practice patterns. Our findings emphasize the need for unified guidance regarding management of these masses to reduce unwarranted variation in care.

External Validation of a Five-Tiered CT Algorithm for the Diagnosis of Clear Cell Renal Cell Carcinoma: A Retrospective Five-Reader Study

BACKGROUND. In 2022, a five-tiered CT algorithm was proposed for predicting whether a small (cT1a) solid renal mass represents clear cell renal cell carcinoma (ccRCC). OBJECTIVE. The purpose of this external validation study was to evaluate the proposed CT algorithm for diagnosis of ccRCC among small solid renal masses. METHODS. This retrospective study included 93 patients (median age, 62 years; 42 women, 51 men) with 97 small solid renal masses that were seen on corticomedullary phase contrast-enhanced CT performed between January 2012 and July 2022 and subsequently underwent surgical resection. Five readers (three attending radiologists, two clinical fellows) independently evaluated masses for the mass-to-cortex corticomedullary attenuation ratio and heterogeneity score; these scores were used to derive the CT score by use of the previously proposed CT algorithm. The CT score's sensitivity, specificity, and PPV for ccRCC were calculated at threshold of 4 or greater, and the NPV for ccRCC was calculated at a threshold of 3 or greater (consistent with thresholds in studies of the MRI-based clear cell likelihood score and the CT algorithm's initial study). The CT score's sensitivity and specificity for papillary RCC were calculated at a threshold of 2 or less. Interreader agreement was assessed using the Gwet agreement coefficient (AC1). RESULTS. Overall, 61 of 97 masses (63%) were malignant and 43 of 97 (44%) were ccRCC. Across readers, CT score had sensitivity ranging from 47% to 95% (pooled sensitivity, 74% [95% CI, 68-80%]), specificity ranging from 19% to 83% (pooled specificity, 59% [95% CI, 52-67%]), PPV ranging from 48% to 76% (pooled PPV, 59% [95% CI, 49-71%]), and NPV ranging from 83% to 100% (pooled NPV, 90% [95% CI, 84-95%]), for ccRCC. A CT score of 2 or less had sensitivity ranging from 44% to 100% and specificity ranging from 77% to 98% for papillary RCC (representing nine of 97 masses). Interreader agreement was substantial for attenuation score (AC1 = 0.70), poor for heterogeneity score (AC1 = 0.17), fair for five-tiered CT score (AC1 = 0.32), and fair for dichotomous CT score at a threshold of 4 or greater (AC1 = 0.24 [95% CI, 0.14-0.33]). CONCLUSION. The five-tiered CT algorithm for evaluation of small solid renal masses was tested in an external sample and showed high NPV for ccRCC. CLINICAL IMPACT. The CT algorithm may be used for risk stratification and patient selection for active surveillance by identifying patients unlikely to have ccRCC.

Impacts of Neighborhood Characteristics and Surgical Treatment Disparities on Overall Mortality in Stage I Renal Cell Carcinoma Patients

Racial/ethnic minority groups in the United States have high renal cell carcinoma (RCC) mortality rates. This study assessed surgical treatment disparities across racial/ethnic groups and impacts of neighborhood socioeconomic characteristics on surgical treatments and overall mortality. Stage I RCC patients diagnosed between 2004 and 2016 from National Cancer Database were included (n = 238,141). We assessed differences in associations between race/ethnicity and treatment patterns using logistic regression and between race/ethnicity and overall mortality using Cox regression with and without neighborhood characteristics in the regression models. When compared to non-Hispanic Whites (NHWs), American Indians/Alaska Natives and non-Hispanic Blacks (NHBs) were more likely not to receive surgical care and all racial/ethnic minority groups had significantly increased odds of undergoing radical rather than partial nephrectomy, even after adjusting for neighborhood characteristics. Including surgical treatment and neighborhood factors in the models slightly attenuated the association, but NHBs had a significantly increased risk of overall mortality. NHBs who underwent radical nephrectomy had an increased risk of mortality (HR 1.15, 95% CI: 1.08-1.23), but not for NHBs who underwent partial nephrectomy (HR 0.92, 95% CI: 0.84-1.02). Neighborhood factors were associated with surgical treatment patterns and overall mortality in both NHBs and NHWs. Neighborhood socioeconomic factors may only partly explain RCC disparities.

Active Surveillance of Renal Masses: The Role of Radiology

Active surveillance of renal masses, which includes serial imaging with the possibility of delayed treatment, has emerged as a viable alternative to immediate therapeutic intervention in selected patients. Active surveillance is supported by evidence that many benign masses are resected unnecessarily, and treatment of small cancers has not substantially reduced cancer-specific mortality. These data are a call to radiologists to improve the diagnosis of benign renal masses and differentiate cancers that are biologically aggressive (prompting treatment) from those that are indolent (allowing treatment deferral). Current evidence suggests that active surveillance results in comparable cancer-specific survival with a low risk of developing metastasis. Radiology is central in this. Imaging is used at the outset to estimate the probability of malignancy and degree of aggressiveness in malignant masses and to follow up masses for growth and morphologic change. Percutaneous biopsy is used to provide a more definitive histologic diagnosis and to guide treatment decisions, including whether active surveillance is appropriate. Emerging applications that may improve imaging assessment of renal masses include standardized assessment of cystic and solid masses and radiomic analysis. This article reviews the current and future role of radiology in the care of patients with renal masses undergoing active surveillance.

Collaborative Review: Factors Influencing Treatment Decisions for Patients with a Localized Solid Renal Mass

CONTEXT

With the addition of active surveillance and thermal ablation (TA) to the urologist's established repertoire of partial (PN) and radical nephrectomy (RN) as first-line management options for localized renal cell carcinoma (RCC), appropriate treatment decision-making has become increasingly nuanced.

OBJECTIVE

To critically review the treatment options for localized, nonrecurrent RCC; to highlight the patient, renal function, tumor, and provider factors that influence treatment decisions; and to provide a framework to conceptualize that decision-making process.

EVIDENCE ACQUISITION

A collaborative critical review of the medical literature was conducted.

EVIDENCE SYNTHESIS

We identify three key decision points when managing localized RCC: (1) decision for surveillance versus treatment, (2) decision regarding treatment modality (TA, PN, or RN), and (3) decision on surgical approach (open vs minimally invasive). In evaluating factors that influence these treatment decisions, we elaborate on patient, renal function, tumor, and provider factors that either directly or indirectly impact each decision point. As current nomograms, based on preselected patient datasets, perform poorly in prospective settings, these tools should be used with caution. Patient decision aids are an underutilized tool in decision-making.

CONCLUSIONS

Localized RCC requires highly nuanced treatment decision-making, balancing patient- and tumor-specific clinical variables against indirect structural influences to provide optimal patient care.

PATIENT SUMMARY

With expanding treatment options for localized kidney cancer, treatment decision is highly nuanced and requires shared decision-making. Patient decision aids may be helpful in the treatment discussion.

Initial Observation of a Large Proportion of Patients Presenting with Clinical Stage T1 Renal Masses: Results from the MUSIC-KIDNEY Statewide Collaborative

BACKGROUND

While surgical excision remains the principal management strategy for clinical T1 renal masses (cT1RMs), the rates of noninterventional approaches are not well known. Most single-institution and population-based series suggest rates below 10%.

OBJECTIVE

To evaluate the use of observation for newly diagnosed cT1RM patients in academic and community-based practices across a statewide collaborative.

DESIGN SETTING AND PARTICIPANTS

The Michigan Urological Surgery Improvement Collaborative-Kidney mass: Identifying and Defining Necessary Evaluation and therapY (MUSIC-KIDNEY) commenced data collection in September 2017 by recording clinical, radiographic, pathologic, and short-term follow-up data for cT1RM patients at 13 diverse practices. Patients with complete data were assessed at >90 d after initial evaluation as to whether observation or treatment was performed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Relationships with outcomes were analyzed using multivariable logistic regression, chi-square test, and Wilcoxon rank-sum test.

RESULTS AND LIMITATIONS

Out of 965 patients, observation was employed in 48% (n = 459), with practice-level rates ranging from 0% to 68%. Patients managed with observation (vs treatment) were significantly older (71.2 vs 62.8 yr, p <  0.0001) and had smaller tumors (2.3 vs 3.4 cm, p <  0.0001). Observation was used for 53.5% of cT1a renal masses, for 29.9% of cT1b renal masses, and for 42.5%, 53.7%, and 63.9% of radiographically solid, Bosniak III-IV cystic, and indeterminate cT1RMs, respectively. Factors significantly associated with observation in multivariable analysis included lesion type (Bosniak III-IV vs solid, p =  0.017), tumor stage (cT1a vs cT1b, p <  0.001), and higher age (p <  0.001). A short duration of follow-up limits the assessment of longer-term patient management.

CONCLUSIONS

Noninterventional management of cT1RMs is common across the MUSIC-KIDNEY collaborative, with wide variability across practices. Factors associated with observation were advanced age, smaller tumor size, and cystic tumor type. Durability of the initial decision for observation (delayed intervention vs active surveillance vs less active surveillance) will be a focus of subsequent study.

PATIENT SUMMARY

The Michigan Urological Surgery Improvement Collaborative: Kidney mass: Identifying and Defining Necessary Evaluation and therapY (MUSIC-KIDNEY) quality improvement collaborative assessed the current utilization of initial observation of a renal mass ≤7 cm across a diverse group of urology practices and found it to be used in 48% of patients. We found that the factors predicting observation were advanced age, smaller tumor size, and cystic tumor type.

Active surveillance for small renal masses in elderly patients does not increase overall mortality rates compared to primary intervention: a propensity score weighted analysis

BACKGROUND

The aim of the study was to test the effect of active surveillance (AS) versus primary intervention (PI) on overall mortality (OM) in elderly patients diagnosed with SRM.

METHODS

Elderly patients (75 years or older) diagnosed with SRMs (<4 cm) and treated with either PI (i.e. partial nephrectomy or kidney ablation) or AS between 2009 and 2018 were abstracted from the renal surgery in the elderly (RESURGE) and Delayed Intervention and Surveillance for small Renal Masses (DISSRM) datasets, respectively. OM rates were estimated among groups with Kaplan Meier method and Cox proportional hazards regression models after applying inverse probability of treatment weighting (IPTW). Multivariable logistic regression model was used to estimate IPTW. Covariates of interest were those unbalanced and/or significantly correlated with the treatment choice or with OM.

RESULTS

A total of 483 patients were included; 121 (25.1%) underwent AS. Sixty patients (12.4%) died. Overall, 6.7% of all deaths were related to cancer. IPTW-Kaplan Meier curves showed a 5-year overall survival rates of 70.0±3.5% and 73.2±4.8% in AS and PI groups, respectively (IPTW-Log-rank P value=0.308). IPTW-Cox regression model did not show meaningfully increased OM rates in AS group (HR: 1.31, 95% CI: 0.69-2.49).

CONCLUSIONS

AS represents an appealing treatment option for very elderly patients presenting with SRM, as it avoids the risks of a PI while not compromising the survival outcomes of these patients.

Distinguishing Benign Renal Tumors with an Oncocytic Gene Expression (ONEX) Classifier

Renal oncocytoma (RO) accounts for 5% of renal cancers and generally behaves as a benign tumor with favorable long-term prognosis. It is difficult to confidently distinguish between benign RO and other renal malignancies, particularly chromophobe renal cell carcinoma (chRCC). Therefore, RO is often managed aggressively with surgery. We sought to identify molecular biomarkers to distinguish RO from chRCC and other malignant renal cancer mimics. In a 44-patient discovery cohort, we identified a significant differential abundance of nine genes in RO relative to chRCC. These genes were used to train a classifier to distinguish RO from chRCC in an independent 57-patient cohort. The trained classifier was then validated in five independent cohorts comprising 89 total patients. This nine-gene classifier trained on the basis of differential gene expression showed 93% sensitivity and 98% specificity for distinguishing RO from chRCC across the pooled validation cohorts, with a c-statistic of 0.978. This tool may be a useful adjunct to other diagnostic modalities to decrease the diagnostic and management uncertainty associated with small renal masses and to enable clinicians to recommend more confidently less aggressive management for some tumors. PATIENT SUMMARY: Renal oncocytoma is generally a benign form of kidney cancer that does not necessarily require surgical removal. However, it is difficult to distinguish renal oncocytoma from other more aggressive forms of kidney cancer, so it is treated most commonly with surgery. We built a classification tool based on the RNA levels of nine genes that may help avoid these surgeries by reliably distinguishing renal oncocytoma from other forms of kidney cancer.

Current management of small renal masses

One of the consequences of the growing use of diagnostic imaging techniques is the notable growth in the detection of small renal masses presumably corresponding to localized tumors that are potentially curable with surgical treatment. When faced with the finding of a small renal mass, radiologists must determine whether it is benign or malignant, and if it is malignant, what subtype it belong to, and whether it should be managed with surgical treatment, with ablative techniques, or with watchful waiting with active surveillance. Small renal masses are now a clinical entity that require management different from the approaches used for classical renal cell carcinomas. In this scenario, radiologists are key because they are involved in all aspects of the management of these tumors, including in their diagnosis, treatment, and follow-up.

Does renal mass biopsy influence multidisciplinary treatment recommendations?

Purpose: To examine how a multidisciplinary team approach incorporating renal mass biopsy (RMB) into decision making changes the management strategy.Methods: A multidisciplinary team comprised of a radiology proceduralist, a pathologist and urologists convened monthly for renal mass conference with a structured presentation of patient demographics, co-mborbidities, tumor pathology, laboratory and radiographic features. Biopsy protocol was standardized to an 18-gauge core needle biopsy using a sheathed apparatus under renal ultrasound guidance. Biopsy diagnostic rate, and concordance with nephrectomy specimens were summarized. Descriptive statistics were used to evaluate influence of RMB on management decisions.Results: A total of 83 patients with a ≤4 cm mass were discussed, and 66% of patients underwent RMB. Of those, 87% were diagnostic with 9% of core biopsies showing benign pathology. Active surveillance (AS) was recommended for 34% of patients with biopsy data as compared to 64% of those without biopsy. Ablation was recommended for 38% of the biopsy cohort compared to 7% without biopsy. Partial nephrectomy rates were similar for both cohorts, approximately 17% and 22%, respectively. Our complication rate was 1.5%, with only 1 Clavien-Dindo Grade 2 complication. Histology was concordant in 93% of patients that ultimately underwent partial nephrectomy after biopsy.Conclusions: Over half of our SRM patients underwent a RMB that provided a diagnosis in 85% of cases. RMB aided in shared decision making by providing insight into the biology of renal masses, which helps to guide multidisciplinary management and consideration of nephron sparing options.

Racial/ethnic disparities in renal cell carcinoma: Increased risk of early-onset and variation in histologic subtypes

Background

Racial/ethnic minority groups have a higher burden of renal cell carcinoma (RCC), but RCC among Hispanic Americans (HAs) and American Indians and Alaska Natives (AIs/ANs) are clinically not well characterized. We explored variations in age at diagnosis and frequencies of RCC histologic subtypes across racial/ethnic groups and Hispanic subgroups using National Cancer Database (NCDB) and Arizona Cancer Registry Data.

Methods

Adult RCC cases with known race/ethnicity were included. Logistic regression analysis was performed to estimate odds and 95% confidence interval (CI) of early‐onset (age at diagnosis <50 years) and diagnosis with clear cell RCC (ccRCC) or papillary RCC.

Results

A total of 405 073 RCC cases from NCDB and 9751 cases from ACR were identified and included. In both datasets, patients from racial/ethnic minority groups had a younger age at diagnosis than non‐Hispanic White (NHW) patients. In the NCDB, AIs/ANs had twofold increased odds (OR, 2.21; 95% CI, 1.88‐2.59) of early‐onset RCC compared with NHWs. HAs also had twofold increased odds of early‐onset RCC (OR, 2.14; 95% CI, 1.79‐2.55) in the ACR. In NCDB, ccRCC was more prevalent in AIs (86.3%) and Mexican Americans (83.5%) than NHWs (72.5%). AIs/ANs had twofold increased odds of diagnosis with ccRCC (OR, 2.18; 95% CI, 1.85‐2.58) in the NCDB, but the association was stronger in the ACR (OR, 2.83; 95% CI, 2.08‐3.85). Similarly, Mexican Americans had significantly increased odds of diagnosis with ccRCC (OR, 2.00; 95% CI, 1.78‐2.23) in the NCDB.

Conclusions

This study reports younger age at diagnosis and higher frequencies of ccRCC histologic subtype in AIs/ANs and Hispanic subgroups. These variations across racial/ethnic groups and Hispanic subgroups may have potential clinical implications.

The Harms of Overdiagnosis and Overtreatment in Patients with Small Renal Masses: A Mini-review

Overdiagnosis and overtreatment refer to the detection and treatment of conditions that would not ultimately affect an individual's health. With increasing detection of small renal masses there is growing awareness of the overdiagnosis and overtreatment of these tumors, supported by studies showing that 15-30% of nephrectomy specimens are pathologically benign, and that many small renal cell carcinomas are indolent. The harms of overdiagnosis and overtreatment are numerous, including psychosocial stressors and renal morbidity, in addition to unnecessary surgical complications. A greater understanding of the potential harms of overdiagnosis and overtreatment is crucial as clinicians focus on optimizing patient selection for renal mass biopsy, active surveillance protocols, and minimally invasive surgery. PATIENT SUMMARY: In this mini-review we discuss the issues of overdiagnosis and overtreatment in patients with kidney cancer. We enumerate the risks of overdiagnosis and overtreatment, and examine the next steps towards preventing these harms.