Radiofrequency ablation for eradication of pulmonary tumor in rabbits

BACKGROUND: Radiofrequency ablation (RFA) has emerged as an alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of pulmonary tumor. METHODS: Eighteen rabbits with pulmonary implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip electrode technique. Group B (n = 6) received sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), postmortem microangiography, and histology. RESULTS: All animals in group B died within 3 months after tumor implantation. Tumor eradication was achieved in 9 of 12 rabbits (75.0%) in group A, of which 4 rabbits survived longer than 3 months free of disease and another 5 rabbits were found free of viable tumor when sacrificed. One rabbit was subjected to incomplete tumor ablation and two rabbits suffered from local tumor relapse and/or lung metastasis. The 3-month survival rate of RFA-treated rabbits was significantly higher (P < 0.01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), pulmonary parenchyma coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology. CONCLUSIONS: Eradication of pulmonary tumor could be achieved with current RFA technique in rabbits. MRI is a useful modality for assessment of lung tumor ablation.     

兔肝VX2肿瘤射频消融后不同区带VEGF的表达和细胞凋亡

目的分析兔肝VX2肿瘤射频消融(RFA)后不同区带血管内皮细胞生长因子(VEGF)的表达和肿瘤细胞凋亡情况。方法将48只兔肝移植VX2肿瘤,建立动物模型,分为实验组(n=42)和对照组(n=6)。对实验组行RFA,分别在术后即刻、1天、2天、1周、2周、3周各处死7只实验兔,留存肿瘤标本,进行HE染色、VEGF检测、Annexin V-FITC/PI标记和流式细胞仪检测,观察不同时间段、不同区带的VEGF变化及细胞凋亡情况。结果实验组RFA术后针道炭化区、热凝固区和消融边界区平均VEGF值差异均有统计学意义(P均0.05);针道炭化区、热凝固区及边界区术后即刻与其他时间点间两两比较差异均有统计学意义(P均0.05);针道炭化区及热凝固区VEGF在术后即刻达高峰,术后1天~3周呈整体下降趋势,消融边界区VEGF在术后即刻到1周呈上升趋势,2周后下降。术后针道炭化区、热凝固区和消融边界区平均肿瘤细胞凋亡率与对照组比较差异均有统计学意义(P均0.05),各区带细胞凋亡率均在术后1天达高峰,后呈下降趋势。结论 RFA后针道区和热凝固区内肿瘤细胞VEGF下降和肿瘤凋亡显著,而消融交界区仍可能有存活的肿瘤细胞;在RFA后第3周时,残留肿瘤细胞的增殖能力可恢复到术前状态,此时宜进一步采取相应的治疗措施。     

肝脏恶性肿瘤射频消融术后早期FS-T2WI消融区周围水肿环评价消融疗效的应用

目的探讨肝脏恶性肿瘤射频消融(RFA)术后早期FS-T2WI消融区周围水肿环形态用于评价RFA疗效的价值。方法收集接受RFA治疗的18例肝癌及4例肝转移瘤患者,于术后第3天行MR平扫,观察FS-T2WI中消融区周围水肿环的形态特点;随访复查MR平扫、多期增强扫描及肿瘤标志物,评价根据FS-T2WI水肿环连续性判断RFA疗效的价值。结果消融后,22例病灶FS-T2WI消融区周围均出现高信号水肿环。19例水肿环连续,其中11例厚薄均匀,8例厚薄不均匀但形态规整、边界清晰;术后随访均无异常强化,肿瘤标志物稳定,提示消融完全。3例水肿环不连续,局部可见外凸稍高信号结节,术后1个月增强MRI可见结节状动脉期强化,血清甲胎蛋白升高,提示消融区域未完全覆盖肿瘤区域,消融不完全。结论肝脏恶性肿瘤RFA后早期FS-T2WI消融区周围水肿环对评价疗效具有一定价值,尤其对于判断短期疗效意义重大。     

经导管栓塞联合射频消融对兔VX2肝肿瘤的干预效果

目的 探讨经导管动脉栓塞术（TAE）联合射频消融（RFA）对兔VX2肝肿瘤的干预效果。方法 将兔VX2肝肿瘤模型分为4组,每组15只。对TACE+RFA组于TACE治疗15 min后行RFA,TAE+RFA组TAE治疗15 min后行RFA,RFA组仅给予RFA,TACE组仅给予TACE。分别于术前1天及术后3、7天检测血清天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）,术后7天检测肿瘤生长率、肿瘤坏死率及Suzuki评分;术后1、3、7天采用免疫组织化学法检测坏死区或凝固区周围肝组织热休克蛋白70（HSP70）表达,计算肝细胞凋亡指数及增殖指数。结果 TACE+RFA组术后3、7天血清ALT、AST水平均高于其他3组（P均<0.05）。术后7天,TACE+RFA组Suzuki评分高于其他3组,TACE+RFA组、TAE+RFA组肿瘤生长率低于RFA组和TACE组、肿瘤坏死率高于RFA组和TACE组（P均<0.05）。4组术后1、3、7天坏死区或凝固区周围肝组织HSP70表达均逐渐升高,TACE+RFA组术后1、3、7天均高于其他3组,术后1、3天TAE+RFA组均高于TACE组和RFA组（P均<0.05）。4组术后1、3、7天坏死区或凝固区周围肝细胞凋亡指数均逐渐降低,TACE+RFA组术后1、3、7天均高于其他3组,TACE组术后1、3天均高于TAE+RFA组、RFA组（P均<0.05）。4组术后3天肝细胞增殖指数均高于术后1、7天,TAE+RFA组术后1、3、7天均高于其他3组,RFA组术后1、3天均高于TACE+RFA组和TACE组（P均<0.05）。结论 TACE+RFA、TAE+RFA抑制兔VX2肝肿瘤生长效果优于单独应用TACE、RFA;TAE+RFA对肝损伤更小,促进肝细胞增殖、抑制其凋亡的效果更好。     

建立兔靠近腹主动脉VX2肝癌模型

目的建立兔邻近腹主动脉VX2肝癌模型,为高强度聚焦超声（HIFU）消融肝脏大血管旁肿瘤研究选择最佳建模时间点提供实验依据。方法采用手术直视下组织块包埋法对45只新西兰大白兔于肝门处接种VX2瘤块,接种后第14、21、28天行MRI,观察成瘤率、肿瘤体积和肿瘤一腹主动脉间距。结果接种后动物存活率为92．11％（41／45）,成瘤率为95．12％（39／41）。MRI示接种后第14天T2WI呈高信号,增强后VIBEFST1WI示肿瘤明显强化;第21天肿瘤T2WI呈高信号,肿瘤不均匀强化;第28天肿瘤边缘环形强化,中心无强化,肿瘤出现继发性坏死;肿瘤体积随时间逐渐增大,肿瘤一腹主动脉间距逐渐减小,差异均有统计学意义（P均〈0．05）。结论直视下组织块包埋法建立兔邻近腹主动脉VX2肝癌模型操作简单、重复性好、成功率高,肿瘤接种后21天为研究HIFU消融肝脏大血管旁肿瘤作用的最佳时间点。     

Radio-frequency ablation of renal cell carcinoma: early clinical experienc.

Purpose: To report the authors' early experience with radio-frequency (RF) ablation of renal cell carcinoma.Materials and Methods: Twenty-four percutaneous RF ablation treatments for nine tumors were performed in eight patients with renal cell carcinoma. Indications included coexistent morbidity, previous surgery, or solitary kidney in patients with a life expectancy shorter than 10 years. Smaller (⩽3-cm) peripheral lesions (n = 3) were treated with single electrodes. All but one of the larger (>3 cm) and/or central lesions (n = 6) were treated with cluster or multiple electrodes. Patients returned for a second treatment when follow-up imaging depicted tumor enhancement. Follow-up imaging was performed at 1 and 3 months and then at 6-month intervals, with a mean follow-up of 10.3 months. Seven patients were alive at least 6 months after their initial treatment.Results: All five exophytic tumors were free of enhancement. One of three central tumors was free of enhancement. One tumor had both central and exophytic components and was free of enhancement. Three tumors were 3 cm or smaller and free of enhancement. Of the six tumors larger than 3 cm, four were free of enhancement.Conclusion: Percutaneous RF ablation is a promising treatment for select patients with renal cell carcinoma. The ultimate role of this modality will continue to evolve and warrants further study.CommentaryNew minimally invasive technologies are currently being applied to the field of nephron-sparing surgery (NSS) for renal cell carcinoma (RCC) in an effort to decrease operative time, pain, morbidity and hospital stay. Methods of tumor ablation have included cryotherapy, radio-frequency ablation (RFA), high intensity focused ultrasound (HIFU), laser and microwave coagulation. These new modalities are currently being administered laparoscopically or percutaneously; ultimately, completely extracorporeal techniques may be feasible.The primary mechanism of tissue destruction with RFA is thermonecrosis. Radio-frequency energy causes high frequency current flow from the needle electrode into the surrounding tissue. This causes ionic agitation, molecular friction, cellular warming with rapid dessication and cell death. The size and configuration of the lesion are related to the amount of energy delivered, ablation time, tissue impedance, electrolyte content of the tissue and surface area of the electrode. It is a major technical challenge to control for each of these variables independently.The major concern with RFA and related ablative technologies is the ability to image the destructive process precisely as it is being administered, thereby minimizing injury to normal adjacent parenchyma while assuring complete tumor ablation. Since a surgical specimen is not removed for pathologic study, histologic documentation of complete tumor destruction and accurate tumor staging/grading are not available. Meticulous long-term clinical and radiographic follow-up of treated patients is ultimately needed to validate the efficacy of ablative techniques such as RFA for treating renal malignancy.Andrew C. Novick, M.D.     

兔肝VX2肿瘤RFA后残余瘤与 炎症的鉴别:CT与病理对照

目的通过CT扫描与病理对照,对兔肝VX2肿瘤RFA后残余瘤与炎症进行鉴别。方法兔肝VX2肿瘤射频消融（RFA）后不同时期行CT及病理检查,观察RFA后不同时期的残余瘤与炎症的CT表现。结果CT增强扫描,残瘤与炎症均表现为周边强化带,炎症还表现为强化带外侧的肝组织由内向外逐渐减弱强化影,炎症的这种强化影于术后第2天最强,之后逐渐减弱,2周后基本消失。结论RFA后1周内,CT增强扫描尚不能准确分辨残瘤与炎症反应带;两周后低密度灶周边出现强化影应考虑为残余瘤存在。     

Probe ablation as salvage therapy for renal tumors in von Hippel-Lindau patients: The Cleveland Clinic experience with 3 years follow-up

BackgroundTo evaluate the efficacy and safety of probe ablative therapy as salvage treatment for renal tumor in von Hippel-Lindau (VHL) patients after previous partial nephrectomy (PN).MethodsMedical records of VHL patients undergoing probe ablative treatment for renal tumors from March 2003 to January 2010 at our institution were retrospectively analyzed.ResultsFourteen VHL patients who were submitted to salvage probe ablative therapy were included in the analysis. Twelve patients (85%) had a solitary kidney. Overall, 33 tumors were ablated by either percutaneous cryoablation (P-Cryo) (n of procedures = 13), radiofrequency ablation (RFA) (n = 14), and laparoscopic cryoablation (L-Cryo) (n = 3). Average maximal renal tumor diameter was 2.6 ± 1 cm. Average ablation time was 18.3 ± 2.1 minutes for P-Cryo, 36.7 ± 17 minutes for RFA, and 17.3 ± 4 minutes for L-Cryo. All procedures were successfully completed without transfusions and intraoperative complications. No early postoperative complications were recorded. Postoperative decline in renal function was minimal and not clinically significant. With a mean follow-up of 37.6 months (range 12–82), 4 patients had a suspicious recurrence on computed tomogaphy/magnetic resonance imaging (CT/MRI) scan and in 3 of them a re-ablation was performed. Actuarial overall and cancer-specific survivals were 92% and 100%, respectively.ConclusionsProbe ablative therapy seems to represent a suitable treatment option for VHL patients with a previous history of PN as it offers a repeatable operation, with a high technical success rate and causing minor changes in renal function.     

入肝血流阻断下射频消融后毁损灶周围肝组织的病理变化

目的:评估血流阻断射频术后毁损灶周围正常肝脏组织的病理变化。方法:兔VX2肝肿瘤接种成功后分为单独射频组与射频联合入肝血流阻断组(联合射频组)。射频采用冷循环射频消融治疗(参数设定为30 W,8 min),入肝血流阻断采用Pringle法。1周后处死动物,通过HE染色观察术后毁损灶周围肝脏组织的病理变化。结果:与单独射频组比较,联合射频组毁损灶周边正常肝组织内中央静脉及Glisson鞘周围可见大量炎症细胞聚集,且肝细胞肿胀,门静脉、中央静脉扩张、胆管上皮增生等病理变化均更明显(均P<0.05)。结论:血流阻断后射频对毁损灶周围正常肝组织的病理损害较单独射频的损害严重。     

125I粒子植入与射频消融对TACE术后AFP阳性中晚期肝细胞癌干预效果的对比分析

目的对比分析125I粒子植入或射频消融(RFA)对TACE术后甲胎蛋白(AFP)阳性中晚期原发性肝细胞癌(HCC)患者的干预效果。方法回顾性分析79例TACE术后AFP阳性的中晚期原发性HCC患者,其中41例接受125I粒子植入(A组),38例接受RFA(B组)。分别于治疗后1、3、6个月评价治疗效果,并检测血清AFP。结果术后1个月,2组治疗有效率差异无统计学意义(P=0.122);术后3、6个月A组治疗有效率均高于B组(P均<0.05)。A、B组术前及术后1个月血清AFP差异均无统计学意义(P均>0.05),术后3、6个月A组AFP均低于B组(P均<0.05)。结论125 I粒子植入治疗TACE术后AFP阳性中晚期HCC临床效果优于RFA,且降低AFP效果更显著。     

肝癌热消融治疗合并出血的相关因素分析

目的探讨肝癌热消融治疗相关出血并发症的发生原因及防治措施。方法回顾性分析接受热消融治疗的1 797例肝癌患者,收集患者相关的临床资料并对发生出血的原因、影响因素进行分析。结果对1 797例患者共3 200个肿瘤行2 356例次热消融治疗,射频消融(RFA)治疗547例次,微波消融(MWA)治疗1 809例次。治疗后共有18例患者发生出血,发生率为0.76%(18/2 356),其中严重出血6例,发生率0.25%(6/2 356);轻微出血12例,发生率0.51%(12/2 356)。相关因素分析结果显示,凝血功能障碍(血小板50×109/L、凝血酶原时间18s)、肿瘤邻近血管以及肝功能Child-Pugh B级可导致出血并发症的风险增高(P均0.05)。结论肝癌热消融治疗相对安全、出血并发症发生率低,但当患者具有凝血功能障碍、肿瘤邻近血管以及肝功能Child-Pugh B级等高危因素时应做好预防措施。     

Percutaneous ultrasound-guided radiofrequency ablation of an allograft renal cell carcinoma: a case report

BackgroundRenal cell carcinomas (RCCs) are rarely described in transplanted kidneys. Available therapeutic strategies range from allograft nephrectomy to nephron-sparing procedures such as partial nephrectomy or image-guided thermal ablation. Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique which provides promising oncologic outcomes in small allograft RCCs while preserving allograft function. So far, only a few cases have been reported in the transplant setting. We describe a renal transplant RCC successfully approached by ultrasound-guided RFA.MethodsA 42-year-old renal transplant recipient developed a small subcapsular allograft RCC at 11 years after transplantation. The decline in glomerular filtration rare prompted us to preserve as much parenchyma as possible. Ultrasound-guided RFA was performed under light sedation and local analgesia in a single session with a Starbust Talon needle.ResultsPostablation contrast-enhanced ultrasound displayed a 25×23 mm avascular area of complete necrosis. After 3 months gadolinium-enhanced magnetic resonance imaging confirmed the absence of viable tumor tissue and while the patient did not experience any graft function reduction (serum creatinine 2.6 mg/dL).ConclusionsImage-guided RFA represents a promising therapeutic modality for small allograft RCCs in recipients with mild graft dysfunction and/or elevated surgical risk. It is associated with low morbidity and parenchymal preservation.     

环五肽RGD靶向的纳米金偶联VEGFsiRNA增强兔VX2肝肿瘤射频消融损伤效应的研究

目的:探讨环五肽RGD(Tyr RGD)靶向的纳米金颗粒(GNPs)偶联VEGF小干扰RNA(Tyr RGDGNPs-VEGFsi RNA)复合物对兔肝脏VX2肿瘤射频消融(RFA)损伤效应的影响。方法:采取开腹肝脏种植VX2肿瘤组织块的方法建立兔VX2肝癌模型。首先将6只肝癌兔均分为两组分别注射Tyr RGD-GNPs-VEGFsi RNA复合物和GNPs,注射48 h后,透射电镜检测两者在肿瘤标本中的聚集和分布情况。然后将30只肝癌兔均分为3组,分别注射Tyr RGD-GNPs-VEGFsi RNA复合物、GNPs、生理盐水48 h后,行RFA治疗,48 h后切取标本,行病理学观察,测量肿瘤毁损体积,TUNEL法检测残癌细胞凋亡。最后将27只肝癌兔均分为3组,分别行RFA+Tyr RGD-GNPsVEGFsi RNA注射,RFA+生理盐水注射、生理盐水注射,饲养至自然死亡,记录生存时间。结果:Tyr RGD-GNPs-VEGFsi RNA复合物在肿瘤中的聚集明显优于GNPs(14.2颗/500 nm视野vs.0颗/500 nm视野,P0.01)。注射Tyr RGD-GNPs-VEGFsi RNA复合物后的RFA治疗毁损体积明显大于注射GNPs和生理盐水(5.12 cm3 vs.1.78 cm3 vs.1.49 cm3,P0.01),且前者残癌区肿瘤细胞凋亡数明显高于后两者(111.7个vs.36.3个vs.34.7个,P0.01),而后两者上述指标差异均无无统计学意义(均P0.05)。RFA+Tyr RGD-GNPs-VEGFsi RNA治疗的肝癌兔较RFA+生理盐水治疗、单纯生理盐水治疗的肝癌兔的平均生存时间明显延长(70.9 d vs.51.2 d vs.43.9 d,P0.01)。结论:Tyr RGD-GNPs-VEGFsi RNA复合物能在肝脏肿瘤中靶向聚集,具有扩大RFA毁损范围和促进肿瘤细胞凋亡的作用,从而增强RFA疗效。     

Surveillance post-radiofrequency ablation for small renal masses: Recurrence and followup

IntroductionSmall renal masses (SRMs), enhancing tumors <4 cm in diameter, are suspicious for renal cell carcinoma (RCC). The incidence of SRMs have risen with the increased quality and frequency of imaging. Partial nephrectomy is widely accepted as a nephron-sparing approach for the management of clinically localized RCC, with a greater than 90% disease-specific survival for stage T1a. Radiofrequency ablation (RFA) has been emerging as an alternative management strategy, with evidence suggesting RFA as a safe alternative for SRMs. We aimed to evaluate the time to recurrence and recurrence rates of SRMs treated with RFA at our institution.MethodsA retrospective review between October 2011 and May 2019 identified 141 patients with a single SRM treated with RFA at Hamilton Health Sciences and St. Joseph’s Healthcare Hamilton. Patients with familial syndromes and distant metastases were excluded. Repeat RFAs of the ipsilateral kidney for incomplete ablation were not considered a new procedure. The primary variable measured was time from initial ablation to recurrence. A Cox proportional hazard regression model was used to identify possible prognostic variables for tumor recurrence defined a priori, including age, gender, mass size, RENAL nephrometry, and PADUA scores.ResultsThe overall average age of our patients was 69.0±11.1 years, with 71.6% being male. Average tumor size was 2.6±0.8 cm. There were 22/154 total recurrences (15.6%) post-RFA. Median followup time was 67 (18–161) months. Those with new recurrences had median time to recurrence of 15 months and no recurrence beyond 53 months. Thirteen of 141 patients had residual disease (9.2%) and were identified within the first eight months post-RFA. The only prognostic variable identified as a predictor of residual disease was tumor size (hazard ratio 2.265; p<0.001).ConclusionsThis study shows the risk of a new recurrence following RFA for SRMs is 6.4%. Most recurrences (9.2%) were a result of residual tumor at the ablation site identified within the first eight months post-RFA. No recurrences were identified beyond 53 months, with a total median followup time of 67 months. Tumor size alone, without need for complex scoring systems, may serve as a predictor of incomplete ablation following RFA and could be used to assist in shared decision-making on management strategies.     

经皮超声引导下射频消融治疗胃癌肝转移疗效分析

目的探讨经皮超声引导下射频消融(RFA)治疗胃癌肝转移的疗效及预后因素。方法回顾性分析55例接受经皮超声引导下RFA治疗的胃癌肝转移患者临床及影像学资料,观察评价患者总体生存率及预后影响因素。结果55例(102个病灶)胃癌肝转移患者1、2、3、5年总体生存率分别为70.45%、42.90%、20.32%及10.16%。RFA治疗后1个月,肿瘤灭活率94.12%(96/102),肿瘤局部复发率15.69%(16/102),肝内新生转移灶发生率52.73%(29/55)。单因素分析示年龄(P=0.015)、肿瘤数目(P=0.011)、RFA前是否有肝外转移(P=0.026)、RFA后是否化疗(P=0.031)是影响患者生存的重要因素。多因素分析示年龄(P=0.033)、肿瘤数目(P=0.004)、RFA后是否化疗(P=0.001)是独立预后因素。RFA治疗后严重并发症的发生率为1.82%(1/55),未发生治疗相关性死亡。结论经皮超声引导下RFA是一种安全、有效的胃癌肝转移治疗方式,年龄、肿瘤数量、RFA后联合化疗是影响患者预后的独立因素。     

Long-term oncologic outcomes following radiofrequency ablation with real-time temperature monitoring for T1a renal cell cancer

ObjectiveFew studies report long-term follow-up of renal cancer treated by radiofrequency ablation (RFA), thus limiting the comparison of this modality to well-established long-term follow-up series of surgically resected renal masses.Herein, we report long-term oncologic outcomes of renal cancer treated with RFA in a single institution.Methods and materialsWe retrospectively reviewed patients treated between November 2001 and October 2012 with laparoscopic-guided or computed tomography–guided RFA. All treatments were performed with real-time thermometry ensuring target ablation temperature (>60°C) was adequately reached. Only patients with biopsy-confirmed T1a-category cancer and a follow-up period>48 months were included in our analysis. Follow-up included office visits, laboratory work, and periodic contrast-enhanced imaging.Survival was calculated using the Kaplan-Meier analysis. Overall complications were reported using the Clavien-Dindo scale.ResultsOf 434 RFA cases, 53 treatments in 50 patients met the inclusion criteria. Of these, 29 were treated with computed tomography–guided RFA and 24 with laparoscopic-guided RFA. The mean follow-up interval was 65.6 months (48.5–120.2), and the mean renal mass size was 2.3 cm (0.3–4.0). There were 4 (7.5%) local recurrences and 1 case of distant metastases with no local recurrence. The 5-year overall survival was 98%, cancer-specific survival was 100%, and recurrence-free survival was 92.5%. The complication rate was 26.4%, which included 71% of Clavien-Dindo grade I and 29% of grade II. Mean estimated glomerular filtration rate preoperatively and at the most recent follow-up visit was 77 and 66 ml/min, respectively.ConclusionsWhen performed on selected patients, while monitoring real-time temperatures to ensure adequate treatment end points, RFA offers favorable long-term oncologic outcomes approaching those reported for partial nephrectomy.     

'Skipping' is still a problem with radiofrequency ablation of small renal tumours

OBJECTIVE: To evaluate the homogeneity and extent of necrosis obtained with next-generation radiofrequency ablation (RFA) equipment and techniques, as incomplete tumour necrosis, or 'skipping', has been documented after RFA of renal tumours and subsequent partial nephrectomy, but this was assumed to result from insufficient energy deposition with first-generation low-energy generators. PATIENTS AND METHODS: In all, 17 patients with solitary renal tumours of 0.5-1.0 cm beyond the sonographically controlled tumour borders. Target temperatures of 105 degrees C were applied in three cycles for 10-30 min at up to 150 W. Tumours were then removed by laparoscopic partial nephrectomy and specimens evaluated by detailed histology. RESULTS: The mean (range) resected tumour size was 22 (11-40) mm, the mean RFA time was 39 (27-59) min and the mean surgical resection time was 25 (12-45) min. In 13 patients, haemostasis was sufficient to avoid the renal pedicle being clamped. Intraoperative repeated positive margins in one patient required a laparoscopic radical nephrectomy. Thirteen (76%) renal masses showed histologically complete ablation of the entire tumour. Of the four RFA failures, three tumours were >3 cm in diameter, two were highly vascularized and three had a very heterogeneous tissue texture. CONCLUSION: Even with state-of-the-art technology, skipping remains a problem with RFA for small renal masses and renders the technique unreliable.     

Thermal ablation for small renal masses: Identifying the most appropriate tumor size cut-off for predicting perioperative and oncological outcomes

ObjectivesTo test TRIFECTA achievement [1) absence of CLAVIEN-DINDO ≥3 complications; 2) complete ablation; 3) absence of ≥30% decrease in eGFR] and local recurrence rates, according to tumor size, in patients treated with thermal ablation (TA: radiofrequency [RFA] and microwave ablation [MWA]) for small renal masses.MethodsRetrospective analysis (2008–2020) of 432 patients treated with TA (RFA: 162 vs. MWA: 270). Tumor size was evaluated as: 1) continuously coded variable (cm); 2) tumor size strata (0.1–2 vs. 2.1–3 vs. 3.1-4 vs. >4 cm). Multivariable logistic regression models and a minimum P-value approach were used for testing TRIFECTA achievement. Kaplan-Meier plots depicted local recurrence rates over time.ResultsOverall, 162 (37.5%) vs. 140 (32.4%) vs. 82 (19.0%) vs. 48 (11.1%) patients harboured, respectively, 0.1 to 2 vs. 2.1 to 3 vs. 3.1 to 4 vs. >4 cm tumors. In multivariable logistic regression models, increasing tumor size was associated with higher rates of no TRIFECTA achievement (OR:1.11; P< 0.001). Using a minimum P-value approach, an optimal tumor size cut-off of 3.2 cm was identified (P< 0.001). In multivariable logistic regression models, 3.1 to 4 cm tumors (OR:1.27; P< 0.001) and >4 cm tumors (OR:1.49; P< 0.001), but not 2.1 to 3 cm tumors (OR:1.05; P= 0.3) were associated with higher rates of no TRIFECTA achievement, relative to 0.1 to 2 cm tumors. The same results were observed in separate analyses of RFA vs. MWA patients. After a median (IQR) follow-up time of 22 (12–44) months, 8 (4.9%), 8 (5.7%), 11 (13.4%), and 5 (10.4%) local recurrences were observed in tumors sized 0.1 to 2 vs. 2.1 to 3 vs. 3.1 to 4 vs. >4 cm, respectively (P= 0.01).ConclusionA tumor size cut-off value of ≤3 cm is associated with higher rates of TRIFECTA achievement and lower rates of local recurrence over time in patients treated with TA for small renal masses.     

Evidence for tumor cell spread during local hepatic ablation of colorectal liver metastases

IntroductionThe aim of the present study was to analyze the impact of cryosurgery (CRYO) on liver metastases compared to other thermoablative techniques. In a rat liver metastases model, evidence for tumor cell spread was analyzed comparing CRYO, radiofrequency ablation (RFA), and laser-induced thermotherapy (LITT).MethodsIn an experimental study, we compared cell spillage in the washout of isolated perfused rat livers undergoing thermal ablation. Within the same model, CC531-GFP rat liver tumors were treated with CRYO, RFA, or LITT and the number of vital tumor cells within the perfusate was measured. Matrix metalloproteinases (MMP-2, MMP-9) were analyzed after in vivo ablation of rat colorectal liver metastases in the third experimental model.ResultsOur data showed pronounced washout of cells after CRYO with a higher amount of intravascular cells and cell detritus compared to RFA and LITT. Only the effluent fluid of cryosurgery-treated livers revealed GFP-stained tumor cells. MMP-2 and MMP-9 expression was significantly higher after cryosurgery than after RFA and LITT.ConclusionWhen using thermoablative techniques, intravascular metastatic cell spillage is highest in CRYO, and increased expression of matrix metalloproteinases may further facilitate tumor cell spread. Therefore, RFA and LITT may be preferable whenever surgical resection of liver tumors is impossible.