Percutaneous Cryoablation of Solitary, Sporadic Renal Cell Carcinoma: Outcome Analysis Based on Clear-Cell versus Papillary Subtypes
With the increasing drive towards individualized cancer care it has become imperative that we understand variation in treatment response patterns to loco-regional therapies, based on the different tumor biology and subtypes.
Percutaneous renal ablation has proven to be a robust locoregional therapy for management of T1a renal tumors however very little is known about variation in oncologic response/benefits based on tumor subtypes. Researchers from Mayo clinic Rochester, Minnesota recently published a retrospective review/analysis of their outcomes of percutaneous renal cryoablation of T1a tumors based on clear cell vs papillary subtypes.
They reviewed 173 treated patients from a single center renal cancer registry with T1a tumors over a 13-year period. Three quarters of the patients had clear RCC and the rest papillary RCC – biopsies were performed prior to or during the cryoablation.
Recurrence rate was higher with cRCC (4 %) vs pRCC (0 %). The 5 yr progression free survival was higher with pRCC (100 %) vs cRCC (88 %). Clear cell RCC had a higher bleeding complication rate (5.2%) vs (0)%. Although none of these findings had statistically significant p values, the trend from these data is interesting.
The paper asks a very pertinent question about variation of renal tumor response to minimally invasive percutaneous cryoablation. This is important in the era of personalized cancer care. By better understanding the variations in tumor response outcomes for T1a renal tumor we could potentially move towards personalizing the post cryoablation surveillance /follow up protocol based on the tumor type. Although this is promising and exciting, there remains a paucity of studies to address this issue, therefore further robust Level 1 studies are required before we can carve out clear evidence driven guidelines for personalizing the post treatment surveillance/follow up imaging.
The paper reaffirms that biopsy is the lynch pin of this new paradigm, therefore it is imperative to perform a biopsy of the renal masses especially as multiple studies including this current study now show a relatively low complication rate for renal mass biopsy. Whether it should be performed before treatment to guide therapy or during the ablation remains controversial. The authors provide their opinion on this matter in the paper.
There are several weakness’ in the paper which are acknowledged by the authors. The main weakness to highlight is that although they were interesting trends suggested by the data, none of the measure variables reached statistical significance. This is likely due the study being inadequately powered to demonstrate the statistical significance. Further pooled data and larger studies are required to address this.
Rodrick C Zvavanjanja MD, MSc, FRCR, DABR(VIR/DR)
Department of Diagnostic and Interventional Radiology
University of Texas at Houston McGovern Medical School