Viable tumor tissue adherent to needle applicators after local ablation: a risk factor for local tumor progression.

BACKGROUND: Local tumor progression (LTP) is a serious complication after local ablation of malignant liver tumors, negatively influencing patient survival. LTP may be the result of incomplete ablation of the treated tumor. In this study, we determined whether viable tumor cells attached to the needle applicator after ablation was associated with LTP and disease-free survival. METHODS: In this prospective study, tissue was collected of 96 consecutive patients who underwent local liver ablations for 130 liver malignancies. Cells and tissue attached to the needle applicators were analyzed for viability using glucose-6-phosphate-dehydrogenase staining and autofluorescence intensity levels of H&E stained sections. Patients were followed-up until disease progression. RESULTS: Viable tumor cells were found on the needle applicators after local ablation in 26.7% of patients. The type of needle applicator used, an open approach, and the omission of track ablation were significantly correlated with viable tumor tissue adherent to the needle applicator. The presence of viable cells was an independent predictor of LTP. The attachment of viable cells to the needle applicators was associated with a shorter time to LTP. CONCLUSIONS: Viable tumor cells adherent to the needle applicators were found after ablation of 26.7% of patients. An independent risk factor for viable cells adherent to the needle applicators is the omission of track ablation. We recommend using only RFA devices that have track ablation functionality. Adherence of viable tumor cells to the needle applicator after local ablation was an independent risk factor for LTP.

Assessment of viable tumour tissue attached to needle applicators after local ablation of liver tumours.

AIM: Local recurrence and needle track seeding are serious complications after local ablation for liver malignancies and potentially affect long-term survival. The aim of this study was to assess the incidence of viable tissue adherent to the needle applicators after ablation to gain insight into the possible mechanisms of local recurrence and needle track seeding. METHODS: A total of 40 consecutive patients underwent 59 local liver ablations. Cells and tissue attached to the needle applicators were analysed for morphology (HE, PAP and Giemsa staining) and viability (G6PD staining). RESULTS: Macroscopic tissue adherence was visible following 31 of the ablative procedures, all with radiofrequency ablation. Four applications were performed percutaneously and 27 during an open procedure. Morphologically intact tumour cells could be identified in 8 patients (20%), and viable tumour cells in 5 patients (12.5%). Morphologically intact tumour cells or viable tumour cells could only be demonstrated when track ablation was not performed. CONCLUSION: Viable tumour cells adherent to the needle applicators were found in an alarming 12.5% of patients after local ablation. We recommend track ablation not only after the procedure but also during any shifting and (re-)positioning to prevent shedding of viable tumour cells during or after ablation.

Combining partial liver resection and local ablation of liver tumours: a preliminary Dutch experience.

BACKGROUND: The combination of partial liver resection and radiofrequency ablation (RFA) is a novel concept in the treatment of unresectable liver malignancies. The aim of this study is to evaluate the results of this combined strategy in the Netherlands. METHODS: Thirty-five patients treated with a combination of partial liver resection and RFA were identified from a prospectively registered pooled multicentre database. All patients were operated between June 1999 and November 2003 in 8 medical centres in The Netherlands. Main outcome parameters were morbidity, mortality, local success rate, and survival. RESULTS: Thirty-seven operations were performed in 35 patients. The group consisted of 20 male and 15 female patients with a median age of 59 years (range 41-76). Seventy-six lesions were resected and RFA was performed to ablate 82 unresectable liver tumours. Twelve patients developed a total of 24 complications, resulting in an overall perioperative morbidity rate of 32%. In two patients major complications resulted in postoperative death (postoperative mortality rate 5.4%). Local success rate after RFA was 88% and the estimated 1-, 2- and 3-year overall survival rates were 84%, 70% and 43%, respectively. CONCLUSION: This strategy should only be performed following strict patient selection and within the context of prospective clinical trials.

Cryoablation induces greater inflammatory and coagulative responses than radiofrequency ablation or laser induced thermotherapy in a rat liver model.

BACKGROUND: Cryoablation (CA), radiofrequency ablation (RFA), and laser induced thermotherapy (LITT) are alternative therapies for patients with unresectable liver tumors. We investigated whether there are different inflammatory and coagulative responses between these techniques. METHODS: Livers of 48 rats were subjected to either CA, RFA, LITT, or sham operation (n = 12 in each group). Blood was withdrawn before, and 1, 3, 6, and 24 h after ablation. Liver enzymes as well as inflammatory and coagulation parameters were determined. Whole liver sections from the coagulated liver lobe were stained for quantification of necrosis and morphologic examination. RESULTS: Histologic examination showed similar volume of complete destruction of liver parenchyma after CA, RFA, or LITT. Transaminase levels as well as the inflammatory response upon CA, as reflected by white blood cell count and cytokine levels, were significantly higher than following RFA or LITT. The systemic intravascular procoagulative state in rats that underwent CA, as reflected by platelets, and levels of sensitive markers for activation of coagulation and fibrinolyis, was also significantly higher. CONCLUSION: CA of liver in rats induces greater inflammatory and coagulative responses than RFA or LITT. The combined activation of inflammation and coagulation may importantly contribute to the higher morbidity after CA.

Experimental and clinical radiofrequency ablation: proposal for standardized description of coagulation size and geometry.

BACKGROUND: Radiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF. METHODS: In a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter. RESULTS: The proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended. CONCLUSIONS: Adoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.

Factors influencing the local failure rate of radiofrequency ablation of colorectal liver metastases.

BACKGROUND: The prognosis of patients with colorectal cancer is poor, especially when there is distant metastatic disease. Local ablation of tumor by radiofrequency ablation (RFA) has emerged as a safe and effective new treatment modality, but its long-term efficacy may be hindered by renewed local tumor growth at the site of RFA. The objectives of this study were to identify risk factors for local RFA failure and to define exclusion criteria for RFA treatment of colorectal liver metastases. METHODS: A total of 199 lesions in 87 patients were ablated with RFA. Factors influencing local failure rates were identified and compared with data from the literature. RESULTS: The local failure rate was 47.2%, and the average time to local disease progression was 6.5 months. Factors that significantly correlated with increased failure rates were metachronous occurrence of liver metastases, large mean lesion size, and central tumor location. CONCLUSIONS: Because accurate electrode placement is pivotal in achieving adequate tumor necrosis, RFA should not be performed percutaneously when electrode placement is impaired. We suggest that lesions >5 cm and lesions located near great vessels or adjacent organs should be treated with open RFA, thus allowing vascular inflow occlusion and complete mobilization of the liver. Lesions that are difficult to reach by electrodes should be approached by an open procedure.