A Phase II Trial of Image-Guided Radiofrequency Ablation of Small Invasive Breast Carcinomas: Use of Saline-Cooled Tip Electrode

Background Local ablative therapy of breast cancer represents the next frontier in the evolution of minimally-invasive breast conservation therapy. We performed this Phase II trial to determine the efficacy and safety of Radiofrequency (RF) ablation of small invasive breast carcinomas. Methods Seventeen patients with biopsy-proven invasive breast cancer, ≤ 1.5 cm in diameter were enrolled in this trial. Under ultrasound guidance, the tumor and a 5 mm margin of surrounding breast tissue were ablated with saline-cooled RF electrode followed by surgical resection. Pathologic and immunohistochemical stains were performed to assess tumor viability. We examined whether loss of ER, PR receptor and pancytokeratin expression following RF ablation would correlate with non-viability. Results Fifteen patients completed the treatment. The mean tumor size was 1.28 cm. The mean ablation time was 21 minutes using a mean power of 35.5 watts. During ablation, the tumors became progressively echogenic that corresponded with the region of severe electrocautery injury at pathological examination. Of the 15 treated patients, NADPH viability staining was available for 14 patients and in 13 (92.8%), there was no evidence of viable malignant cells. ER, PR expression and pancytokeratin immunohistochemistry analysis were unreliable surrogates for determining non-viability. Following RF ablation, 2 patients developed skin puckering. Conclusions RF ablation is a promising minimally invasive treatment of small breast carcinomas, as it can achieve effective cell killing with a low complication rate. Further research is necessary to optimize this image-guided technique and evaluate its future role as the sole local therapy.     

Radiofrequency Thermal Ablation of Breast Cancer Local Recurrence: A Phase II Clinical Trial

Background  The role of radiofrequency (RF) ablation to treat local recurrence of breast cancer is unknown. Methods  We conducted a two-stage phase II clinical trial. Eligible patients had a histologically confirmed noninflammatory and ≤3 cm ipsilateral breast tumor recurrence. The tumor site was identified by intraoperative sonography. A LeVeen needle electrode (RadioTherapeutics Corp, Mountain View, Calif) was inserted into a single site within the tumor and radiofrequency ablation was performed using a RF-2000 generator (RadioTherapeutics Corp). After completion of radiofrequency, a mastectomy was performed. Conventional staining and nicotinamide adenine dinucleotide-diaphorase (NADH-diaphorase) cell viability staining were performed. Results  During the first stage, procedures were uneventful. Conventional, cytokeratin, and NADH-diaphorase staining identified persistent viable tumor cells in the RF-ablated region in three patients. This phase II trial was stopped after completion of the first stage because of insufficient efficacy. Conclusion  We demonstrate in this study that RF ablation is a potential technique to destroy local recurrence of breast tumors but the technique we tested in this phase II clinical trial had insufficient efficacy to recommend its use in routine.     

Treatment of renal tumors with radiofrequency ablation

BACKGROUND: Radiofrequency (RF) energy has been investigated as a minimally invasive modality for ablating small renal tumors. Recent advances in the application of this technology have improved its safety and effectiveness. MATERIALS AND METHODS: We describe the technology of RF application and review the current delivery systems as applied to renal tumor ablation. We also review relevant animal studies, which have revealed the natural history of ablated renal tissue. Finally, we examine recent human trials with an emphasis on longer-term follow-up, imaging, complications, and successful ablation according to tumor location within the kidney; i.e., central v peripheral. RESULTS: Radiofrequency ablation can be performed safely in a minimally invasive fashion either percutaneously or laparoscopically. Energy delivery varies, and available systems include dry, wet, cooled-tip, and bipolar electrodes. Heat rise and subsequent charring in the tissue adjacent to the electrode is limited by temperature or impedance-based feedback systems. In animal studies, ablation results in complete cell kill, as judged by nicotinamide adenine dinucleotide diaphorase staining. Clinical trials with intermediate follow-up show excellent success rates. Tumors >3 cm and central tumors have a higher recurrence rate after RFA than smaller, more peripheral tumors. CONCLUSIONS: The current literature suggests that RFA is a promising minimally invasive method of treating small renal tumors. Nevertheless, long-term follow-up is still required, and questions remain regarding the optimal delivery system, duration of ablation, and method of surveillance.     

Treatment of invasive breast carcinoma with ultrasound-guided radiofrequency ablation

BACKGROUND: Radiofrequency ablation (RFA) is a minimally invasive thermal ablation technique. This study reports the safety and efficacy of RFA as a minimally invasive strategy for breast cancers <3 cm diameter in postmenopausal women. METHODS: Twenty-two postmenopausal women (aged 60 years or older) with clinical T-1N0 core biopsy proven breast cancers were studied. Thermocoagulation was undertaken using a sonographically guided RF probe under local anesthesia and sedation. The ablated tumor was resected between 1 and 2 weeks later. Endpoints were technical success, completeness of tumor kill, marginal clearance, skin damage, and patient reports of pain and procedural acceptability. RESULTS: The procedure was well tolerated and cosmesis was excellent. Pathology revealed a central ablation zone surrounded by hyperemia. Coagulative necrosis was complete in 19 of 22 patients. Disease at the ablation zone margin was found in 3 patients and 5 patients had disease distant to the ablation zone consisting of multifocal tumors (2), in-transit metastasis (1), and extensive ductal carcinoma in situ with microinvasive carcinoma (2). Ninety-five percent of patients would be willing to have RFA again. CONCLUSIONS: Radiofrequency ablation can be safely applied in an outpatient setting with acceptable patient tolerance. By itself, RFA cannot be considered effective local therapy. Trials to evaluate RFA complemented with breast irradiation are justified.     

Radiofrequency ablation for the treatment of non-small cell lung cancer in marginal surgical candidates

OBJECTIVE: Treatment options for patients with non-small cell lung cancer who are not surgical candidates or who refuse operation are limited. Radiofrequency ablation represents a potential less invasive option for these patients. Our initial experience with radiofrequency ablation for peripheral, primary non-small cell lung cancer is reported. METHODS: We treated 21 tumors in 18 patients. Median age was 75 (range 58-86) years. Cancer stages were I (n = 9), II (n = 2), III (n = 3), and IV (n = 4). Patients with stage IV disease included 3 with recurrence after previous lobectomies and 1 with a synchronous liver metastasis also treated with radiofrequency ablation. Median tumor diameter was 2.8 cm (range 1.2-4.5 cm). Radiofrequency ablation was delivered by minithoracotomy in 2 cases and by a computed tomography-guided percutaneous approach in 16 patients. Computed tomographic and positron emission tomographic scans were used to evaluate recurrence and radiographic response in ablated nodules. RESULTS: One postoperative death occurred from pneumonia after open radiofrequency ablation. Median hospital stay was 2.5 days. A chest tube or pigtail catheter was required in 7 patients (38.9%) for procedure-related pneumothoraces. At a median follow-up of 14 months, 15 patients (83.3%) were alive. Local progression occurred in 8 nodules (38.1%). Mean and median progression-free intervals were 16.8 and 18 months, respectively. For stage I cancers, mean progression-free interval was 17.6 months. Median progression-free interval was not reached. CONCLUSION: This study demonstrates the feasibility of radiofrequency ablation for small, peripheral non-small cell lung cancer tumors. Local control is comparable to, if not better than, that provided by radiotherapy. Radiofrequency ablation should continue to be evaluated by thoracic surgeons as a noninvasive therapy for the high-risk patient with non-small cell lung cancer.     

Ultrasound-guided radiofrequency ablation of early breast cancer in a resection specimen: Lessons for further research

PurposeTo assess the feasibility and effectiveness of radiofrequency ablation (RFA) in breast cancer, using different histopathologic staining methods to evaluate tissue viability.Materials and methodsIn twenty patients with unifocal small (≤1, 5 cm) invasive ductal carcinoma, ultrasound-guided RFA was performed immediately after surgery. Cell viability was assessed using cytokeratin 8 (CK 8) and nicotinamide adenine dinucleotide diaphorase (NADHD) in addition to hematoxylin–eosin (HE).ResultsAt histopathological examination, ex vivo RFA resulted in complete cell death of the target lesion in 17/20 patients. In two cases viable ductal carcinoma in situ (DCIS) was found just outside the completely ablated lesion.ConclusionRFA of small invasive breast cancer seems to be a feasible treatment option. Both NADHD and CK 8 demonstrate a clear and comparable demarcation between viable and non-viable tissue. A high level of accuracy is required in proper positioning of the needle electrode and a “hot retraction” is mandatory.     

Image and Pathological Changes after Radiofrequency Ablation of Invasive Breast Cancer: A Pilot Study of Nonsurgical Therapy of Early Breast Cancer

Background

The surgical treatment of early breast cancer has proceeded to less invasive approaches with better cosmetic results. The current study was undertaken to evaluate the clinical and pathological findings after radiofrequency ablation (RFA) without resection for a longer period of time.

Method

A total of 14 patients with breast cancer were enrolled. All patients were diagnosed to have invasive ductal carcinoma, and the median breast tumor size was 12 mm (range, 6–20 mm). Six patients received RFA treatment followed by immediate resection and eight patients without resection. The patients without resection were evaluated by ultrasound, MRI, and the pathological findings of a core needle biopsy after RFA. The removed specimens were examined by hematoxylin-eosin (HE) staining and nicotinamide adenine dinucleotide (NADH) diaphorase staining. The median follow-up of the patients was 39.9 months.

Results

NADH staining was necessary to diagnose complete tumor cell death in the tissue for 3 months after RFA. However, HE staining alone could confirm the effect without NADH staining more than 6 months after RFA. Post-RFA, MRI scans clearly demonstrated the area as a complete ablated lesion in all patients without resection. The ablated area detected by MRI or ultrasound became gradually smaller. All patients that underwent RFA with no resection were alive without relapse.

Conclusion

RFA therefore could be an effective alternative to partial mastectomy for early breast cancer. Further research will be necessary to establish the standardization of the indications, as well as the optimal techniques and post treatment evaluation modalities.     

Radiofrequency Ablation of Invasive Breast Carcinomas: A Phase II Trial

Background Local ablative therapy of breast cancer represents the next frontier in the minimally invasive breast-conservation treatment. We conducted a phase II trial to evaluate radiofrequency ablation (RFA) of invasive breast carcinomas. Methods Consecutive patients from two Mexican Institutions with invasive breast cancers < 4 cm, with no multicentric tumors and no previous chemotherapy were included in this trial. Under ultrasound guidance, the tumor and a 5 mm margin of surrounding breast tissue were ablated with saline-cooled RFA electrode followed by surgical resection. Routine pathologic analysis and viability evaluation with NADPH-diaphorase stain were performed to assess tumor ablation. Procedure-associated morbidity was recorded. Results Twenty-five patients were included. Mean patient age was 55.3 years (range 42–89 years). Mean tumor size was 2.08 cm (range 0.9–3.8 cm). Fourteen tumors (56%) were <2 cm. The mean ablation time was 11 minutes using a mean power of 35 W. During ablation, the tumors become progressively echogenic that corresponded with the region of severe RFA injury at pathologic examination. Of the 25 patients treated, NADPH stain showed no evidence of viable malignant cells in 19 patients (76%), with significant difference between tumors <2 cm (complete necrosis in 13 of 14 cases, 92.8%) vs. those >2 cm (complete necrosis 6 of 11 cases, 54.5%) (P < .05). No significant morbidity was recorded. Conclusions RFA is a promising minimally invasive treatment of small breast carcinomas, as it can achieve effective cell killing with a low complication rate. Further studies are necessary to optimize the technique and evaluate its future role as local therapy for breast cancer.     

Radiofrequency ablation lesions in a pig liver model.

BACKGROUND: Radiofrequency (RF) ablation has been reported as a means of liver tumor destruction. This study evaluates the use of ultrasound monitoring of radiofrequency lesion creation and describes the morphology, histologic characteristics, and vascular effects of radiofrequency ablations in a pig liver model. MATERIALS AND METHODS: Hemodynamic monitoring was established and laparotomies were performed in 50-kg pigs. Under ultrasound guidance, radiofrequency needle probes were placed in the liver at predetermined locations. Radiofrequency energy was applied over 15 min to generate lesions 3 cm in diameter. Eighty lesions were generated in 10 animals. At the completion of the experiment, the lesions were examined with ultrasound and then excised for CT, gross, and histologic examination. RESULTS: There were no adverse systemic effects. Ultrasound imaging demonstrated the size, shape, and position of the lesions. Gross examination demonstrated a core of ablated tissue with a surrounding 1- to 2-mm hemorrhagic perimeter. Lesion volumes averaged 12.8 cc(3) (range 5-34 cc(3)). Final lesion shape and size were frequently altered by the cooling effect of local blood flow. Histologic stains demonstrated microvascular thrombosis and coagulative necrosis within the lesions. There appeared to be 100% cellular destruction within the lesion by cytochemical staining. CONCLUSIONS: We demonstrated that RF ablation is capable of killing large volumes of normal liver tissue; however, local vasculature plays a significant a role in defining the ultimate size and shape of the lesion created. This may interfere with the utility of radiofrequency ablation as a modality for local tumor control.     

Heat fixation of cancer cells ablated with high-intensity-focused ultrasound in patients with breast cancer

BACKGROUND: High-intensity-focused ultrasound (HIFU) is a noninvasive thermal ablation technique. This study reports the use of histological techniques for the pathological assessment of HIFU effects in patients with breast cancer. METHODS: Twenty-three patients with biopsy-proven breast cancer underwent HIFU treatment for primary breast lesion. Mastectomy was performed on all patients after HIFU. By using histological examinations, the surgical specimens were assessed to explore HIFU effects on breast cancer. RESULTS: Coagulation necrosis of targeted tumors was confirmed by microscopy in 23 patients. Tumor cells presented typical characteristics of coagulation necrosis in the peripheral region of the ablated tumor in all patients. However, in 11 of 23 patients, hematoxylin and eosin staining showed normal cellular structure in the central ablated tumor. By using electronic microscopy and nicotinamide adenine dinucleotide-diaphorase stain, those who had normal-appearing cancer cells were not viable. CONCLUSIONS: HIFU can cause the heat fixation of ablated tumor through thermal effect.     

Increased activity of matrix metalloproteinase 2 and 9 after hepatic radiofrequency ablation

BACKGROUND: Radiofrequency (RF) ablation of hepatic metastases from colorectal cancer (CRC) is associated with a high rate of local and intrahepatic tumor recurrence. Matrix metalloproteinases (MMPs) play an important role in inflammation, tissue repair and tumor cell invasion and metastasis. MMP-2 and MMP-9 are associated with increased risk of recurrence and decreased survival in patients with colorectal cancer. The primary aim of the study was to determine if hepatic RF ablation increased MMP-2 and MMP-9 activity in the transition zone surrounding the coagulated hepatic tissue. MATERIALS AND METHODS: Twelve pigs were randomized to hepatic RF ablation with (n = 6) or without (n = 6) hepatic vascular occlusion (Pringle maneuver). Four days after ablation tissue specimens were collected from the transition zone surrounding coagulated hepatic tissue, and from normal hepatic parenchyma. MMP activity was quantified by gelatin zymography. Cellular localization of MMPs was determined by immunohistochemistry using antibodies against MMP-2, MMP-9, and the macrophage marker CD68. RESULTS: MMP-2 and MMP-9 activity was increased in the transition zone compared to normal hepatic parenchyma, with ratios of 3.0 (P = 0.005) and 2.6 (P = 0.001), respectively. Pringle maneuver did not influence MMP activity. MMP-2 and MMP-9 expression was localized to macrophages in the transition zone. CONCLUSIONS: Hepatic RF ablation is associated with increased expression of MMP-2 and MMP-9 in macrophages in the transition zone surrounding the coagulated hepatic parenchyma. These findings may contribute to the understanding of possible mechanisms for the high recurrence rates observed in patients after RF ablation of CRC hepatic metastases.     

Phase II trial of radio frequency ablation of renal cancer: evaluation of the kill zone

PURPOSE: We report on the pathological evaluation of renal tumors after intraoperative radio frequency ablation performed immediately before surgical nephrectomy. MATERIALS AND METHODS: Ten patients with renal tumors were enrolled in a prospective, Institutional Review Board approved phase II trial of radio frequency ablation. Following surgical exposure of the kidney a single 12-minute radio frequency ablation of the tumor was performed using the Radionics Cool-tip RF Radio Frequency Ablation System (Radionics, Burlington, Massachusetts). The tumor was then excised via radical or partial nephrectomy. Gross and histological evaluations of the tumor were performed, including evaluation with nicotinamide adenine dinucleotide vital staining. RESULTS: All 10 tumors were confirmed histologically to be renal cell carcinoma. Mean tumor size was 3.2 cm. (range 1.4 to 8.0). Of the 10 tumors 8 were completely ablated with a mean treatment margin of 6.75 mm. (range 2 to 13). Of the 2 tumors that were incompletely treated 1 never attained a temperature sufficient for tissue destruction and the other measured 8 cm., far exceeding the expected ablation volume of treatment protocol. CONCLUSIONS: This study represents the initial report of the histological outcome of saline cooled radio frequency ablation of renal tumors. Our data indicate that it can completely destroy renal cancers while transmitting minimal collateral damage to surrounding renal parenchyma. Further investigation is required to determine long-term oncological outcome.     

Radiofrequency ablation of early breast cancer followed by delayed surgical resection--a promising alternative to breast-conserving surgery

To examine the radiofrequency ablation (RFA) reliability in early breast cancer, we performed RFA followed by delayed surgical resection on 41 patients with invasive or non-invasive breast carcinoma less than 2 cm. MRI scans were obtained before ablation and resection. Excised specimens were examined pathologically by haematoxylin-eosin and nicotinamide adenine dinucleotide-diaphorase staining. 40 patients completed 1 RFA session, which was sufficient to achieve complete tumour cell death. Overall complete ablation rate was 87.8% (36/41). There were no treatment-related complications other than that of a superficial burn in 1 case. After RFA, the tumour was no longer enhanced on MRI in 25/26 (96.2%) cases. Residual cancer, which was suspected on MRI in 1 case, was confirmed pathologically. MRI could be an applicable modality to evaluate therapeutic effect. RFA could be an alternate local treatment option to breast-conserving surgery for early breast cancer.     

Ultrasound-Guided Laser-Induced Thermal Therapy for Small Palpable Invasive Breast Carcinomas: A Feasibility Study

Background  The next step in breast-conserving surgery for small breast carcinomas could be local ablation. In this study, the feasibility of ultrasound-guided laser-induced thermal therapy (LITT) is evaluated. Methods  Patients with large-core needle biopsy-proven invasive, palpable breast carcinoma (clinically ≤2 cm) underwent ultrasound-guided LITT, followed by surgical excision. Completeness of ablation was determined by both hematoxylin and eosin staining and nicotinamide adenosine diaphorase staining. Results  Fourteen patients completed the treatment. The mean histological tumor size was 17 mm (range, 8–37 mm); 6 of 14 tumors were histologically larger than the clinical entry threshold of 2 cm. The power applied in all patients was 7 W, and the mean treatment time was 21.4 min (range, 15–30 min). In one patient, a skin burn occurred, and one patient had a localized pneumothorax that could be treated conservatively. In 7 (50%) of 14 patients, the tumor was completely ablated, as confirmed by nicotinamide adenosine diaphorase staining. In 11 cases, extensive in-situ carcinoma was present. In one case, the in-situ carcinoma was also completely ablated. A total of seven (88%) of eight tumors <2 cm in size were completely ablated versus one (17%) of six tumors that were ≥2 cm in size (P = .026). Conclusions  Successful LITT of invasive breast cancer seems to be feasible when confined to small (<2 cm) nonlobular carcinomas without surrounding extensive in-situ component and angioinvasion. However, to implement LITT in a curative setting, improvements in imaging to more reliably preoperatively assess tumor size and monitoring of fiber tip placement and treatment affect are essential.     

Feasibility study on radiofrequency ablation followed by partial mastectomy for stage I breast cancer patients

To evaluate the safety and reliability of thermal ablation therapy instead of breast-conserving surgery (BCS), we performed radiofrequency ablation (RFA) for clinical stage I breast cancer patients. Subjects were T1N0 breast cancer patients with no extensive intraductal components. Under general anesthesia, sentinel node biopsy was performed, followed by RFA and BCS. Resected specimens were examined at 5-mm intervals by hematoxylin–eosin (H&E) staining and nicotinamide adenine dinucleotide (NADH) diaphorase staining. Thirty of the 34 eligible patients were enrolled. RFA-related adverse events were observed in nine patients: two with skin burn and seven with muscle burn. Twenty-six patients (87%) showed pathological degenerative changes in tumor specimens with H&E staining. In 24 of the 26 cases (92%) examined by NADH diaphorase staining, tumor cell viability was diagnosed as negative. RFA proved to be reliable and feasible in clinical stage I breast cancer, with no extensive intraductal components. Randomized clinical trials are needed to compare RFA with BCS.     

Magnetic resonance imaging for assessment of radiofrequency lesions in kidney tissue immediately after ablation: an experimental study

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) is an attractive minimally invasive treatment option for small renal masses. The purpose of this study was to investigate the morphologic imaging appearance of RF lesions immediately after the ablation of kidney tissue using standard clinical MR sequences, as well as to investigate the correlation between MR and gross lesion size. MATERIALS AND METHODS: Ablations were performed 17 times in a standardized model of ex-vivo perfused porcine kidneys using a resistance-controlled RF device (250 W, 470 kHz) and a nonexpandable bipolar applicator inserted into the center of healthy renal parenchyma. The RF current was applied for 9 minutes at 20 W. Imaging was performed after ablation using standard clinical MR sequences: morphologic T(1)/T(2)- weighted images and an isotropic post-contrast T(1) high-resolution measurement (VIBE). Maximum lesion diameters were measured in three directions and were compared with the measurements of the gross lesions. Histologic (hematoxylin + eosin and nicotinamide adenine dinucleotide staining) and statistical analyses were performed. RESULTS: The gross pathologic examination showed a firm, white-yellow ablation zone sharply demarcated from the untreated tissue. The histologic examination confirmed cellular viability outside but not in the treatment zone. The RF lesions were hyperintense on T(1)-weighted images and hypointense on T(2)-weighted images. The lesion size measured in the VIBE images correlated best with the macroscopic lesion size (N = 16). CONCLUSIONS: Morphologic MR T(1) and T(2) sequences of RF lesions immediately after ablation produce reliable and consistent imaging characteristics. The post-contrast, high-resolution sequence (VIBE) enables the extent of the lesion to be determined accurately. The potential uses of this imaging strategy in clinical practise warrant further investigation on human renal-cell carcinoma.     

Radiofrequency ablation of synchronous bilateral renal cell carcinoma

Objectives: The treatment of synchronous bilateral renal cell carcinoma is challenging. Radiofrequency ablation has been increasingly applied in the management of renal tumors. Herein, we report our experience of radiofrequency ablation on 12 patients with synchronous bilateral renal cell carcinoma. Methods: From March 2006 to September 2010, 12 patients with bilateral synchronous sporadic renal cell carcinoma (29 lesions overall) were identified from our kidney database. The mean age was 62.3 years (range 35–81). The mean tumor diameter was 4.5 cm (range 0.9–9.0). Three patients received unilateral radiofrequency ablation and contralateral radical nephrectomy, whereas nine patients received bilateral radiofrequency ablation. The oncological and functional outcomes were analyzed. Contrast‐enhanced computed tomography examinations were carried out at day 7, and at 3 and 6 months after the procedure, and every 6 months thereafter. Results: The mean follow‐up period was 33 months (range 10–64). The local tumor control rate was 93.1% (27/29). Cancer‐specific survival and the overall survival rates were 100%. No death or renal failure after the procedure was found. In patients who underwent bilateral radiofrequency ablation, the latest mean glomerular filtration rate had not significantly declined compared with preoperative levels (93.7 ± 13.0 mL/min/1.73 m²vs 96.9 ± 13.3 mL/min/1.73 m², respectively; P > 0.05). Conclusion: Radiofrequency ablation shows encouraging outcomes in the treatment of bilateral renal cell carcinoma. It can provide adequate local tumor control and cancer‐specific survival compared with nephron‐sparing surgery while not affecting the renal function.     

Time course of nicotinamide adenine dinucleotide diaphorase staining after renal radiofrequency ablation influences viability assessment

BACKGROUND AND PURPOSE: Nicotinamide adenine dinucleotide (NADH) diaphorase staining has been used to confirm cell viability or death after radiofrequency ablation (RFA) of renal tissue. The time course over which NADH staining status converts from viable to non-viable after a lethal insult has not been defined for renal RFA, but the change may not be immediate. Our objective was to assess porcine renal tissue for viability using NADH diaphorase staining at various times after RFA. MATERIALS AND METHODS: Seven pigs underwent monopolar RFA of both kidneys followed by needle biopsy of the ablation zone before and immediately after ablation and at 15-minute intervals thereafter. Initially, a single kidney was treated, and the contralateral kidney was treated 2 weeks later. Biopsies were taken from untreated renal parenchyma in a similar time course after nephrectomy to examine the effect of ischemia. All biopsy specimens, as well as representative sections of the ablation zone, were subjected to NADH staining and reviewed by a pathologist who was blinded to the tissue treatment. RESULTS: Most of the post-RFA biopsy specimens (86%) showed non-viable tissue. However, 14% of the specimens revealed viable tissue as late as 150 minutes after RFA. Therefore, none were positive. In the nephrectomy parenchyma, 92% of the biopsy specimens showed viable tissue as late as 4 hours after the onset of ischemia. CONCLUSION: Staining for NADH can establish tissue non-viability after RFA, but the timing of staining after treatment must be considered when interpreting results to avoid false positive tests. Tissue that is apparently viable by NADH staining within 2.5 hours of RFA may in fact have been ablated.     

Pathologic Correlation Study of Microwave Coagulation Therapy for Hepatic Malignancies Using a Three-Ring Probe

Microwave coagulation therapy (MCT) for the ablation of unresectable hepatic malignancies is a promising alternative to radiofrequency and cryoablation techniques. There are few data on the clinical effectiveness of MCT. In vivo pathologic evaluation of ablated tumor tissue is not well described for the three-ring microwave probe. The study design was a prospective trial enrolling patients with resectable hepatic malignancies. Lesions underwent in vivo MCT with the three-ring probe prior to liver resection. Gross and histologic evaluations of the tumor were performed, including nicotinamide adenine dinucleotide (NADH) vital staining. A total of nine patients with metastatic colon cancer were enrolled and had NADH stains performed of their pathologic specimens. The median size of the metastasis being ablated was 3.5 cm (range, 1.5–12.3). Fifty-six percent of the tumors demonstrated evidence of spontaneous coagulative necrosis on immediate histologic examination. The median dimensions of the ablation zones were 5 cm (range, 3–7) × 4.5 cm (range, 2.5–5.2) × 4.2 cm (range, 2–5) with a 5-min ablation at 60 W. The median ablation volume was 50.6 cm³ (range, 9–78). NADH vital staining was performed of the ablation zones with 100% absence of staining in the tumor tissue and in benign hepatic parenchyma, which is consistent with irreversible cellular damage. In conclusion, in vivo MCT of hepatic malignancies with the three-ring probe produces nonviable tumor cells after a 5-min ablation. The ablation time is significantly shorter than other available ablative techniques. Immediate histologic exam produces some evidence of coagulative necrosis. Further study of this promising technology is warranted. Poster presentation at the Society of Surgical Oncology annual meeting, March 24, 2006, San Diego, CA.     

Histopathological findings after radiofrequency (RITA) treatment for prostate cancer

Radiofrequency interstitial tumor ablation (RITA) is a thermal ablation method that uses needles and low radiofrequency (RF) energy. The aim of our study was to evaluate the histopathology of thermal lesions induced by RF energy delivered interstitially in prostate cancer patients who subsequently underwent prostatectomy, and to determine the feasibility, effectiveness and safety of this new method in a pilot study.