Active surveillance of small renal masses: progression patterns of early stage kidney cancer.

BACKGROUND: Most early stage kidney cancers are renal cell carcinomas (RCCs), and most are diagnosed incidentally by imaging as small renal masses (SRMs). Indirect evidence suggests that most small RCCs grow slowly and rarely metastasize. OBJECTIVE: To determine the progression and growth rates for newly diagnosed SRMs stratified by needle core biopsy pathology. DESIGN, SETTING, AND PARTICIPANTS: A multicenter prospective phase 2 clinical trial of active surveillance of 209 SRMs in 178 elderly and/or infirm patients was conducted from 2004 until 2009 with treatment delayed until progression. INTERVENTION: Patients underwent serial imaging and needle core biopsies. MEASUREMENTS: We measured rates of change in tumor diameter (growth measured by imaging) and progression to ≥ 4 cm, doubling of tumor volume, or metastasis with histology on biopsy. RESULTS AND LIMITATIONS: Local progression occurred in 25 patients (12%), plus 2 progressed with metastases (1.1%). Of the 178 subjects with 209 SRMs, 127 with 151 SRMs had>12 mo of follow-up with two or more images, with a mean follow-up of 28 mo. Their tumor diameters increased by an average of 0.13 cm/yr. Needle core biopsy in 101 SRMs demonstrated that the presence of RCC did not significantly change growth rate. Limitations included no central review of imaging and pathology and a short follow-up. CONCLUSIONS: This is the first SRM active surveillance study to correlate growth with histology prospectively. In the first 2 yr, the rate of local progression to higher stage is low, and metastases are rare. SRMs appear to grow very slowly, even if biopsy proven to be RCC. Many patients with SRMs can therefore be initially managed conservatively with serial imaging, avoiding the morbidity of surgical or ablative treatment.

Assessing outcomes in probe ablative therapies for small renal masses.

The increasing incidence of renal-cell carcinoma can be largely attributed to the increased detection of small renal masses (SRMs) via abdominal imaging. These lesions tend to have a slow rate of growth and low malignant potential, and hence, minimally invasive treatments and active surveillance have been developed for these low-risk tumors to minimize treatment-related morbidity. Radiofrequency ablation and cryotherapy are the principal less-invasive approaches, and their initial oncologic efficacy and complication profiles have been favorable. Suboptimal definition of the relevant outcomes of treatment, a dearth of prospective and randomized data, and relatively short follow-up in the context of the natural history of SRMs pose challenges in the assessment of the efficacy and outcomes of thermal ablation of renal-cell carcinoma. Better pretreatment characterization of the biology of these tumors, more effective real-time treatment monitoring, and standardization of outcome definitions and follow-up are needed to better clarify the effectiveness and role of these treatments. This review highlights these potential pitfalls in the assessment of outcomes of probe ablation of SRMs.

Small (< or = 4 cm) cortical renal tumors: characterization with multidetector CT.

BACKGROUND: To determine if the pathology of small (< or = 4 cm) solid renal tumors can be predicted from findings on multidetector CT. METHODS: This retrospective study included 46 patients (median age, 60 years; range, 32-91 years; 27 males, 19 females) with 47 tumors who underwent triphasic renal CT with pathology correlation. Two radiologists reviewed CT studies blinded to pathology results and recorded the morphologic and enhancement features of the tumors. RESULTS: The 47 tumors (median diameter, 2.5 cm; range, 0.6-4.0 cm) included: 26 (55%) clear cell renal cell carcinomas; 9 (19%) oncocytomas; 7 (15%) papillary renal cell carcinomas; 2 (4%) chromophobe renal cell carcinomas; 2 (4%) inflammatory pseudotumors; and 1 (2%) angiomyolipoma with minimal fat. Amongst the three commonest tumors, heterogeneity was seen in 23/26 (88%) clear cell renal cell carcinomas, 6/9 (67%) oncocytomas, and 2/7 (29%) papillary renal cell cancer. Median (minimum-maximum) absolute nephrographic phase enhancement (nephrographic minus unenhanced phase) was: clear cell renal cell carcinomas 65 HU (34-120), oncocytomas 80 HU (51-111), and papillary renal cell carcinomas 16 HU (7-32). CONCLUSION: Absolute nephrographic phase enhancement of < or = 32 HU distinguished papillary renal cell carcinomas from clear cell renal cell carcinomas and oncocytomas.

Contemporary results of percutaneous biopsy of 100 small renal masses: a single center experience.

PURPOSE: Percutaneous biopsy of small renal tumors has not been historically performed because of concern about complications and accuracy. We reviewed our experience with percutaneous needle biopsy of small renal masses to assess the safety and accuracy of the procedure, the potential predictors of a diagnostic result and the role of biopsy in clinical decision making. MATERIALS AND METHODS: A total of 100 percutaneous needle biopsies of renal masses less than 4 cm were performed between January 2000 and May 2007 with 18 gauge needles and a coaxial technique under ultrasound and/or computerized tomography guidance. A retrospective chart review was performed to document the complication rate and the ability to obtain sufficient tissue for diagnosis. Tumor size, tumor type (solid vs cystic), image guidance, biopsy number and core length were assessed for the ability to predict a diagnostic biopsy. RESULTS: No tumor seeding or significant bleeding was observed. Of the core biopsies 84 (84%) were diagnostic for a malignant (66) or a benign (18) tumor. Larger tumor size and a solid pattern were significant predictors of a diagnostic result. Histological subtyping and grading were possible on core biopsies in 93% and 68% of renal cell carcinomas, respectively. A total of 20 patients underwent surgery after a diagnostic biopsy. The histological concordance of biopsies and surgical specimens was 100%. CONCLUSIONS: Percutaneous needle biopsy of renal masses less than 4 cm is safe and provides adequate tissue for diagnosis in most cases. Larger tumor size and a solid pattern are significant predictors of a successful biopsy. Renal tumor biopsy decreases the rate of unnecessary surgery for benign tumors and can assist the clinician with treatment decision making, especially in elderly and unfit patients.

Watchful waiting for small renal masses.

Small renal masses (SRMs; < 4 cm in diameter) account for most renal tumors treated today. Incidental early detection of SRMs by abdominal imaging results in favorable grade and stage migration to renal cell carcinoma, and also increases detection of benign renal tumors. As a result, most SRMs manifest indolent biological behavior with excellent prognosis. Despite the increased use of minimally invasive laparoscopic surgery, nephron-sparing techniques, and percutaneous ablation therapy, selected patients are managed by initial active surveillance, reserving therapy for progression. Older patients and those with competing risks due to medical comorbidities are excellent candidates for active surveillance; their risk of early progression due to growth or metastases appears to be low. Active surveillance should not be recommended for younger, healthier patients until prognostic factors are better defined. Needle core use for improved histopathologic characterization of SRMs should be considered before recommending treatment.

Expanding the indications for laparoscopic radical nephrectomy.

PURPOSE OF REVIEW: Laparoscopic radical nephrectomy is an established treatment for patients with clinical T1 renal cell carcinoma who are unsuitable for nephron-sparing surgery. In this review we summarize the expanding indications for laparoscopic nephrectomy, including large tumors, locally advanced disease, venous thrombi and cytoreductive surgery. RECENT FINDINGS: Laparoscopic nephrectomy remains the foremost conventional laparoscopic procedure in urologic surgery. Multiple studies have demonstrated the feasibility of laparoscopic radical nephrectomy for stage T2 tumors, showing less morbidity and earlier return to activity compared to the open approach. Confirmation of durable oncologic control requires randomized prospective trials with longer follow-up. With growing experience, laparoscopic surgery has been extended to patients with renal cell carcinoma associated with limited local invasion and lymph node metastases. Experimental studies demonstrate the technical feasibility of laparoscopic radical nephrectomy in the presence of renal vein and inferior vena cava thrombi. In well-selected patients with metastatic renal cell carcinoma, laparoscopic cytoreductive nephrectomy can be performed safely, with less morbidity than open nephrectomy. SUMMARY: Minimally invasive surgery results in significantly less postoperative morbidity than does open surgery. The intermediate oncologic outcomes of laparoscopic radical nephrectomy for advanced renal cell carcinoma are comparable to those historically achieved with open radical nephrectomy. Longer follow-up is needed to confirm survival equivalence.