ORIGINAL RESEARCH E18 April 2014 • InterventionalOncology360.com Outcomes Following CT-Guided Percutaneous Radiofrequency Ablation of Primary Renal Tumors Nancy Lee, MS 1 ; John H. Rundback, MD 2 ; Kevin Chaim Herman, MD 2 ; John Kerns, MD 2 ; Ravit Barkama, MD 2 From the 1 George Washington University School of Medicine and Health Sciences, Washington, DC, and the 2 Interventional Institute, Holy Name Medical Center, Teaneck, New Jersey. Abstract: Purpose: The purpose of this study was to analyze outcomes in a single-center cohort of patients undergoing CT-guided percutaneous renal radiofrequency ablation (rRFA) to determine if lesion size was a dif- ferentiator of outcomes, and to describe the temporal changes in lesion size following rRFA. Materials and Methods: Forty lesions in 37 patients (27 males, 10 females; mean age 70±13 years) were treated with rRFA from 2006 to 2013. Patient, tumor, and treatment characteristics were analyzed. Statistical analysis included the entire treated cohort with particular attention paid to subgroupings based on (a) whether patients had a renal mass <3 cm or ≥3 cm, and (b) whether the lesion was biopsy-proven renal-cell carcinoma (RCC). To evaluate lesion changes after ablation, a mixed-effects ANOVA model was fit to lesion size values over time. Results: Kaplan-Meier survival curves showed trends toward worse primary recurrence and overall survival in lesions ≥3 cm, but these were not statistically significant (P=.13 and P=.27 respectively). Secondary recurrences were the same in both groups. The rate of change over time in lesion size following rRFA did not differ significantly either by initial lesion size (P=.65), or between biopsy-proven and non-biopsy-proven RCC (P=.46). Conclusion: rRFA is safe and effective in treating kidney tumors. Overall success of tumor ablation was unrelated to initial size. Serial changes in tumor size after ablation are similar regardless of original size and whether the lesion had been proven RCC by biopsy. Key words: carcinoma, renal cell carcinoma, radiofrequency ablation. R enal cell carcinoma (RCC) constitutes the majority of kidney malignancies. 1 The number of RCC cases is increasing with approximately 65,000 new cases diagnosed each year in the United States. 1,2 Almost twice as many men as women are diagnosed with RCC, and the age at di- agnosis peaks between ages 50 and 80 years. 2,3 Ciga- rette smoking and obesity have consistently been es- tablished as risk factors. 1 Guidelines indicate active surveillance, surgical in- tervention, and minimally invasive therapy as manage- ment methods for RCC. 4 Renal radiofrequency abla- tion (rRFA) is a favorable alternative in patients who are poor surgical candidates because it spares kidney tissue and retains renal function. Renal radiofrequency ablation has no negative effects on glomerular filtra- tion rate in the short or intermediate term, 5 and it also poses less risk for developing chronic kidney disease (CKD) when compared to radical nephrectomy. 6,7 Many studies have shown high clinical success rates Rundback_v.indd 18 4/16/14 4:25 PM Copyright HMP Communications
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ORIGINAL RESEARCH
E18April 2014 • InterventionalOncology360.com
Outcomes Following CT-Guided Percutaneous Radiofrequency Ablation of Primary Renal TumorsNancy Lee, MS1; John H. Rundback, MD2; Kevin Chaim Herman, MD2; John Kerns, MD2; Ravit Barkama, MD2
From the 1George Washington University School of Medicine and Health Sciences, Washington, DC,
and the 2Interventional Institute, Holy Name Medical Center, Teaneck, New Jersey.
Abstract: Purpose: The purpose of this study was to analyze outcomes in a single-center cohort of patients undergoing CT-guided percutaneous renal radiofrequency ablation (rRFA) to determine if lesion size was a dif-ferentiator of outcomes, and to describe the temporal changes in lesion size following rRFA. Materials and Methods: Forty lesions in 37 patients (27 males, 10 females; mean age 70±13 years) were treated with rRFA from 2006 to 2013. Patient, tumor, and treatment characteristics were analyzed. Statistical analysis included the entire treated cohort with particular attention paid to subgroupings based on (a) whether patients had a renal mass <3 cm or ≥3 cm, and (b) whether the lesion was biopsy-proven renal-cell carcinoma (RCC). To evaluate lesion changes after ablation, a mixed-effects ANOVA model was fit to lesion size values over time. Results: Kaplan-Meier survival curves showed trends toward worse primary recurrence and overall survival in lesions ≥3 cm, but these were not statistically significant (P=.13 and P=.27 respectively). Secondary recurrences were the same in both groups. The rate of change over time in lesion size following rRFA did not differ significantly either by initial lesion size (P=.65), or between biopsy-proven and non-biopsy-proven RCC (P=.46). Conclusion: rRFA is safe and effective in treating kidney tumors. Overall success of tumor ablation was unrelated to initial size. Serial changes in tumor size after ablation are similar regardless of original size and whether the lesion had been proven RCC by biopsy.
(P=.13, Figure 2A) and overall survival (P=.27, Figure
2B) in larger lesions, these trends were not statistically
significant.
Serial changes in lesion size after ablation were mod-
eled as a function of time. The rate of change over time
in lesion size following rRFA did not differ significant-
ly either by initial lesion size (<3 cm vs ≥3 cm, P=.65;
Figure 3A), or between biopsy-proven and non-biop-
sy-proven RCC (P=0.46; Figure 3B). The regression
line for the <3 cm group was lesion size (cm)=2.2139
cm–0.02208 cm×(number of months). For the ≥3 cm
group, the regression line was lesion size (cm)=3.6034
cm–0.01683 cm×(number of months). These models
thus estimate a reduction in treated lesion size (maxi-
mal diameter) over the course of 3 months by 0.066
cm in the <3 cm group, and by 0.050 cm in the ≥3
cm group. Over 12 months, estimated reductions in
treated lesion size are 0.265 cm in the <3 cm group
Figure1. Examples of successful and recurrent masses after rRFA. Successful RFA of a small renal tumor is shown in Figures 1A through 1C. Post contrast renal MRI shows a 2.5 cm solid interpolar left renal mass (A, arrow). RFA was performed with a 3 cm LeVeen electrode positioned centrally within the lesion (B, arrowhead). A follow-up CT performed 8 months later shows successful ablation with no residual tumor enhancement (C, asterisk). The le-sion is now smaller, measuring 2.0 cm in greatest dimension. Recurrence after RFA of a large renal tumor is shown in Figures 1D through 1G. A CT scan shows a 3.3 cm exophytic right renal mass (D, arrow). Ablation was performed with a 3.5 cm LeVeen electrode positioned deep (E, asterisk) and centrally (F, asterisk) within the mass. The patient initially did well, but a follow-up CT scan performed 29 months after the procedure (G) shows focal recurrence (ar-rowhead). The patient subsequently underwent partial nephrectomy.
Figure 3. Rate of change in lesion size over time post renal radiofrequency ablation treatment. There was no significant difference in serial change in lesion size re-gardless of initial lesion size or biopsy status of lesion.
Figure 2. Kaplan-Meier survival curve of primary recurrence and overall survival. There was no significant difference in primary recurrence or overall survival between patients with lesions ≥3 cm and those with lesions <3 cm.
and 0.202 cm in the ≥3 cm group.
The pooled intercept and slope for the entire
population based on equal weighting over the 2
groups yielded the following regression line: lesion
size (cm)=2.9087 cm–0.01946 cm×(number of
months). This model thus estimates a reduction of
0.058 cm in treated lesion size over the course of 3
months and 0.233 cm over 12 months.
The regression line for the lesions that were not
biopsy-proven RCC was lesion size (cm)=3.236
cm–0.01547 cm×(number of months). For biop-
sy-proven RCC, the regression line was lesion size
(cm)=2.6276 cm–0.02376 cm×(number of months).
These models thus estimate a reduction in treated
lesion size (maximal diameter) over the course of
3 months by 0.046 cm in the non-biopsy-proven
group, and by 0.071 cm in the biopsy-proven group.
Over 12 months, estimated reductions in treated le-
sion size are 0.186 cm in the non-biopsy-proven
group and 0.285 cm in the biopsy-proven group.
0
1
2
3
4
5
6
7
8
9
0 10 20 30 40 50 60 70
Lesion
Size (cm)
Time (months)
Linear Regression -‐ Serial Change in Lesion Size
0
1
2
3
4
5
6
7
8
9
0 10 20 30 40 50 60 70
Lesion
Size (cm)
Time (months)
Linear Regression -‐ Serial Change in Lesion Size
Mean age (with SD) 70±13 65±13 76±10 P=.0039Student t-test
Diabetes 12 (32) 5 (25) 7
(37) P=.9732
Hypertension 25 (68) 12 (60) 15 (79) Chi-square test
Other history 17 (46) 7 (35) 10 (53)
*Missing glomerular filtration rate data for 1 patient in ≥3 cm group; 1 patient with 2 lesions <3 cm only ac-counted for one in <3 cm group.**Missing serum creatinine info for 1 patient in ≥3 cm group; 1 patient with 2 lesions <3 cm only accounted for one in <3 cm group.‡Type of intervention: partial nephrectomy of contralateral kidney.
TABLE 5. PUBLISHED RESULTS OF STUDIES COMPARING THERMAL ABLATIVE PROCEDURES (CRYOABLATION AND RADIOFREQUENCY ABLATION) TO SURGICAL PROCEDURES (PARTIAL NEPHRECTOMY AND RADICAL NEPHRECTOMY).
du JA. Durable oncologic outcomes after radiofrequency
ablation: experience from treating 243 small renal masses
over 7.5 years. Cancer. 2010;116(13):3135-3142.
14. Levinson AW, Su LM, Agarwal D, et al. Long-term on-
cological and overall outcomes of percutaneous radio
frequency ablation in high risk surgical patients with a
solitary small renal mass. J Urol. 2008;180(2):499-504.
Disclosure: The authors have completed and re-turned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no disclo-sures related to the content of this manuscript.Manuscript received February 16, 2014; provision-al acceptance given March 18, 2014; final version accepted March 25, 2014.
Address for correspondence: John H. Rundback, MD, 718 Teaneck Road, Teaneck, New Jersey 07666, United States. Email: [email protected] name.org
Suggested citation: Lee N, Rundback JH, Her-man KC, Kerns J, Barkama R. Outcomes follow-ing CT-guided percutaneous radiofrequency abla-tion of primary renal tumors. Intervent Oncol 360. 2014;2(4):E18-E31.