Small renal masses in the era of personalized medicine: Tumor heterogeneity, growth kinetics, and risk of metastasis

Improving Renal Tumor Biopsy Prognostication With BAP1 Analyses

CONTEXT.—

Active surveillance of small renal masses highlights the need for accurate prognostication of biopsies.

OBJECTIVE.—

To comprehensively evaluate the accuracy of biopsies in assessing known prognostic parameters including histologic subtype by comparison with subsequent nephrectomy samples.

DESIGN.—

We retrospectively identified patients at University of Texas Southwestern Medical Center, Dallas, Texas, who had a biopsy for a renal mass between 2004-2018. Biopsy samples were evaluated for known prognostic factors such as tumor grade, necrosis, sarcomatoid/rhabdoid change, and BRCA1-associated protein-1 (BAP1) status, which we previously showed is an independent prognostic factor for clear cell renal cell carcinoma. Accuracy was determined by comparison with subsequent analyses of nephrectomy specimens. Statistical analyses were performed to assess biopsy accuracy and correlation with tumor size and pathologic stage.

RESULTS.—

From 805 biopsies with a diagnosis of renal neoplasm, 178 had subsequent resection of the biopsied tumor. Concordance rate for histologic subtype was 96.9% (κ [w], 0.90; 95% CI, 0.82-0.99) and excellent for small renal masses (98.8%; κ [w], 0.97; 95% CI, 0.90-1). Amongst the prognostic variables evaluated, BAP1 immunohistochemistry in clear cell renal cell carcinoma had the highest agreement (94.8%; κ [w], 0.83; 95% CI, 0.66-0.99). The presence of 1 or more aggressive features (grade 3-4, tumor necrosis, BAP1 loss, sarcomatoid/rhabdoid change) in a biopsy significantly correlated with pT stage (P = .004).

CONCLUSIONS.—

Biopsy analyses showed high accuracy for subtyping renal tumors, but it underestimated several poor prognostic features. Addition of BAP1 for clear cell renal cell carcinoma may increase prognostic accuracy. If validated, routine incorporation of BAP1 immunohistochemistry in clear cell renal cell carcinoma biopsies may refine prognosis and aid in the selection of patients for active surveillance.

Retroperitoneoscopic partial nephrectomy using a 980/1470-nm dual-diode laser for small exophytic renal tumors

Laser-supported laparoscopic partial nephrectomy is a promising new technique, but remains under experiment. We presented our single institutional experience of laparoscopic partial nephrectomy using the 980/1470-nm dual-diode laser system to investigate its feasibility, and oncological and functional outcomes. The study retrospectively evaluated 25 patients with small exophytic renal tumors, who underwent laparoscopic partial nephrectomy using a 980/1470-nm dual-diode laser. The demographics, surgical data, complications, pathological variables, oncological, and functional outcomes were reviewed. The changes in hemoglobin and estimated glomerular filtration rate (eGFR) before and after surgery were statistically analyzed. The investigators operated on a total of 25 patients. The off-clamping technique was performed for 23 cases, while the other two cases required renal artery clamping due to unsatisfactory hemostasis. The tumor diameter was 24.6± 6.2 mm, and the mean operative time was 104.4± 23.4 min. The median estimated intraoperative blood loss (EBL) was 100 ml (range 50-600 ml). No major complications (Clavien-Dindo >II) occurred perioperatively. The mean change in hemoglobin before and after the operation was 9 g/l, with a P value of <0.001. The mean decrease in eGFR from before the surgery to the 6-month follow-up was 1.4 ml/min, with a P value of 0.463. The postoperative histopathology evaluation did not demonstrate a positive surgical margin. No recurrence or metastasis was found during the follow-up (mean 24 months). Laparoscopic partial nephrectomy using a 980/1470 nm dual-diode laser appears to be a feasible and oncological satisfactory technique for the treatment of small renal mass (SRM), with the advantages of reducing warm ischemia time.

CT-based radiomic model predicts high grade of clear cell renal cell carcinoma

PURPOSE

To compare the predictive models that can incorporate a set of CT image features for preoperatively differentiating the high grade (Fuhrman III-IV) from low grade (Fuhrman I-II) clear cell renal cell carcinoma (ccRCC).

MATERIAL AND METHODS

One hundred and fourteen patients with ccRCC treated with a partial or radical nephrectomy were enrolled in the training cohort. The six non-texture features, including Pseudocapsule, Round mass, maximal tumor diameter (Diameter_max), intratumoral artery (Artery_tumor), enhancement value of the tumor (TEV) and relative TEV (rTEV), were assessed for each tumor. The texture features were extracted from the CT images of the section with the largest area of renal mass at both corticomedullary and nephrographic phases. The least absolute shrinkage and selection operator (LASSO) was used to screen the most valuable texture features to calculate a texture score (Texture-score) for each patient. A logistic regression model was used in the training cohort to discriminate the high from low grade ccRCC at nephrectomy. The predictors would include all non-texture features in Model 1, all non-texture features and Texture-score in Model 2, and Texture-score in Model 3. The performance of the predictive models were tested and compared in an independent validation cohort composed of 92 cases with ccRCC.

RESULTS

Inter-rater agreement was good for each non-texture feature and Texture-score (the concordance correlation coefficient or Kappa coefficient > 0.70). The Texture-score was calculated via a linear combination of the 4 selected texture features. The three models shown good discrimination of the high from low grade ccRCC in the training cohort and the area under receiver operating characteristic curve (AUC) was 0.826 in Mode 1, 0.878 in Model 2 and 0.843 in Model 3, and a significant different AUC was found between Model 1 and Model 2. Application of the predictive models in the validation cohort still gave a discrimination (AUC > 0.670), and the Texture-score based models with or without the non-texture features (Model 2 and 3) showed a better discrimination of the high from low grade ccRCC (P < 0.05).

CONCLUSION

This study presented the Texture-score based models can facilitate the preoperative discrimination of the high from low grade ccRCC.

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.

Prevalence and Management of Incidental Small Testicular Masses Discovered on Ultrasonographic Evaluation of Male Infertility

PURPOSE

We report the safety of surveillance of small testicular masses incidentally discovered during evaluation of male infertility.

MATERIALS AND METHODS

We retrospectively reviewed a prospectively collected database to identify patients with male infertility found to have incidental small testicular masses (hypoechoic lesions less than 10 mm) on scrotal ultrasound. The men were offered close surveillance with interval imaging and office followup. Patient and imaging characteristics were collected to compare the surveillance and surgical groups with additional comparisons between benign and malignant pathologies to elucidate predictors of underlying malignancy.

RESULTS

Of 4,088 men in whom scrotal ultrasound was completed for male infertility evaluation 120 (2.9%) were found to have a subcentimeter testicular mass. Average followup was 1.30 years (range 0.1 to 16.9). A total of 18 men (15%) proceeded to extirpative surgery while 102 remained on surveillance at last followup. In those with at least 1 month of followup the mean lesion growth rate was -0.01 mm per year. Reasons for surgery included testicular exploration for infertility, mass growth, positive tumor markers, history of testis cancer, concerning imaging characteristics and patient choice. Six of the 18 men who underwent surgery were found to have malignancy, which was seminoma in all. All malignant lesions were greater than 5 mm on initial imaging and demonstrated vascularity, although size and vascularity were not significantly different from those of benign lesions on final pathology findings. No patients demonstrated advanced or recurrent disease.

CONCLUSIONS

Small testicular masses are not uncommon, especially in the infertile male population. Most of these masses do not show significant growth during long-term evaluation and can be safely surveilled with close followup.

Predictors of growth kinetics and outcomes in small renal masses (SRM ≤4 cm in size): Tayside Active Surveillance Cohort (TASC) Study

OBJECTIVE

To determine outcomes of small renal masses (≤4 cm) on active surveillance and explore factors which can influence their growth.

PATIENTS AND METHODS

Two hundred twenty six patients between January 2007 and December 2014 were analysed using cross-linked methodology of healthcare data and independent review. Cancer specific and non-specific survival were the primary outcomes. Growth kinetics, factors influencing growth and need for interventions were secondary outcomes.

RESULTS

101 (64.4%) solid and 4 (5.9%) cystic SRMs showed growth. 43 (19.02%) of SRMs required treatment interventions. Seven patients (7/158; 4.4%) died due to renal cancer at a median follow-up of 21.7 (SD 10.6, min 6-42) months, all in solid category. Independent review of serial radiological imaging of these seven cases showed two patients had subtle metastatic disease at the initial presentation, and 5 of the 7 did not adhere to recommended imaging regime. 33 (33/158; 20.8%) died due to other causes including non-renal cancers (14/158; 8.8%). Multivariate analyses showed that lower eGFR at baseline, co-morbidities and tumour location were independently associated with growth in size.

CONCLUSIONS

A higher cancer-specific mortality was seen in the present study compared to the reported literature. Independent critical review of imaging of cases with poor outcome underscored the importance of adherence to a robust protocol including follow up. Comorbid conditions had a significant impact on growth and overall survival of patients with SRMs.

Ultrasound-guided radiofrequency ablation for cT1a renal masses in poor surgical candidates: mid-term, single-center outcomes

OBJECTIVES

Surgical management of small renal masses can be challenging in frail patients and thus modalities such as radiofrequency ablation (RFA) have emerged as valid alternative options. The aim of the current study was to present mid-term oncological and functional results on a series of patients with cT1a renal cell carcinomas (RCCs) who were unfit for surgery and underwent RFA using ultrasound guidance under local anesthesia.

METHODS

Data from patients fulfilling the study selection criteria were retrospectively collected. RENAL nephrometry score was used for tumor description. Parametric tests were used for data analysis and survival curves were estimated using the Kaplan-Meier method.

RESULTS

Overall, 32 patients (mean±standard deviation age, 72.4 ± 7.6 years) with biopsy-proven RCCs (tumor size, 23.75 ± 10.44 mm and RENAL score, 5.28 ± 1.33) underwent 32 RFA sessions. Twenty-seven patients (84.4%) had low complexity masses and five patients had masses of intermediate complexity (15.6%) according to RENAL score categorization. Over a follow-up period of 22.1 ± 13.7 months, one case of primary treatment failure was recognized (primary technical success 97.0%), and overall, three patients were diagnosed with residual disease (primary technique effectiveness 90.6%). No major complications occurred during the postprocedure 90-day follow up, while no difference was found in serum creatinine and estimated glomerular filtration rate pre and post procedure. Patients with intermediate-complexity renal lesions had shorter time to recurrence in comparison to low-complexity masses (p = 0.002). All patients were alive at the time of study data analysis without diagnosed metastases.

CONCLUSIONS

Percutaneous RFA of small RCCs using ultrasound-based guidance under local anesthesia can be an effective alternative method for managing patients who are unfit for surgery.

Clear cell renal cell tumors: Not all that is "clear" is cancer

Continued improvement of our understanding of the clinical, histologic, and genetic features of renal cell tumors has progressively evolved renal tumor classification, revealing an expanding array of distinct tumor types with different implications for prognosis, patient counseling, and treatment. Although clear cell renal cell carcinoma is unequivocally the most common adult renal tumor, there is growing evidence that some "clear cell" renal neoplasms, such as exemplified by multilocular cystic clear cell renal neoplasm of low malignant potential (formerly multilocular cystic renal cell carcinoma), do not have the same potential for insidious progression and metastasis, warranting reclassification as low malignant potential tumors or benign neoplasms. Still other novel tumor types such as clear cell papillary renal cell carcinoma have been more recently recognized, which similarly have shown a conspicuous absence of aggressive behavior to date, suggesting that these too may be recategorized as noncancerous or may be premalignant neoplasms. This importance for prognosis is increasingly significant in the modern era, in which renal masses are increasingly found incidentally by imaging techniques at a small tumor size, raising consideration for less aggressive management options guided by renal mass biopsy diagnosis, including imaging surveillance, tumor ablation, or partial nephrectomy.

Current Status of Focal Cryoablation for Small Renal Masses

Focal cryoablation is an established minimally invasive technique for the treatment of small renal masses. Because of the lack of robust evidence, it is indicated in selected patients who have relative contraindications to extirpative approaches. With appropriate selection of patients, cryoablation is safe and effective. Main advantages are low risk for complication, minimal invasiveness, and good functional outcomes; oncological outcomes require further studies. The role of the percutaneous approach has been expanding because of its ability to reduce pain and hospitalization, the possibility of performing the procedure under sedation, and the fact that it is potentially more cost effective.

The Past, Present, and Future in Management of Small Renal Masses

Management of small renal masses (SRMs) is currently evolving due to the increased incidence given the ubiquity of cross-sectional imaging. Diagnosing a mass in the early stages theoretically allows for high rates of cure but simultaneously risks overtreatment. New consensus guidelines and treatment modalities are changing frequently. The multitude of information currently available shall be summarized in this review. This summary will detail the historic surgical treatment of renal cell carcinoma with current innovations, the feasibility and utility of biopsy, the efficacy of ablative techniques, active surveillance, and use of biomarkers. We evaluate how technology may be used in approaching the small renal mass in order to decrease morbidity, while keeping rates of overtreatment to a minimum.