Short- and long-term outcomes of hepatectomy combined with intraoperative radiofrequency ablation for patients with multiple primarily unresectable colorectal liver metastases: a propensity matching analysis

BACKGROUND

Hepatectomy combined with intraoperative radiofrequency ablation (IORFA) is a strategy to eliminate all tumors in patients with multiple colorectal liver metastases (CRLM). This study aimed to evaluate the surgical and oncological outcomes of hepatectomy + IORFA for multiple unresectable CRLM.

METHODS

We included patients who underwent combined hepatectomy and IORFA for multiple unresectable CRLM (n = 67) or hepatectomy alone (n = 268) for CRLM. Patients were matched in a 1:1 propensity score analysis to compare the short- and long-term outcomes between groups.

RESULTS

Patients in hepatectomy + IORFA group had a median number of 10 liver lesions. Postoperative morbidity and the rate of major complications was similar between groups (P = 0.362, P = 1.000). The median overall survival (OS), progression free survival (PFS) and hepatic recurrence free survival (HRFS) was similar between groups (3-year OS: 54.2% versus 60.9%, P = 0.389; 3-year PFS: 7.9% versus 19.6%, P = 0.148; 3-year HRFS: 16.7% versus 31.5%, P = 0.202). Re-hepatectomy or radiofrequency ablation was used to treat 47.5% of hepatic recurrences, and the median OS was significantly higher than for patients treated with systemic treatment alone (P < 0.001).

CONCLUSIONS

Combining hepatectomy and IORFA could provide comparable survival rates for patients with multiple unresectable CRLM compared to those with resectable CRLM treated with hepatectomy alone.

Software-based planning of ultrasound and CT-guided percutaneous radiofrequency ablation in hepatic tumors

Objectives

Radiofrequency ablation (RFA) can be associated with local recurrences in the treatment of liver tumors. Data obtained at our center for an earlier multinational multicenter trial regarding an in-house developed simulation software were re-evaluated in order to analyze whether the software was able to predict local recurrences.

Methods

Twenty-seven RFA ablations for either primary or secondary hepatic tumors were included. Colorectal liver metastases were shown in 14 patients and hepatocellular carcinoma in 13 patients. Overlap of the simulated volume and the tumor volume was automatically generated and defined as positive predictive value (PPV) and additionally visually assessed. Local recurrence during follow-up was defined as gold standard. Sensitivity and specificity were calculated using the visual assessment and gold standard.

Results

Mean tumor size was 18 mm (95% CI 15–21 mm). Local recurrence occurred in 5 patients. The PPV of the simulation showed a mean of 0.89 (0.84–0.93 95% CI). After visual assessment, 9 incomplete ablations were observed, of which 4 true positives and 5 false positives for the detection of an incomplete ablation. The sensitivity and specificity were, respectively, 80% and 77% with a correct prediction in 78% of cases. No significant correlation was found between size of the tumor and PPV (Pearson Correlation 0.10; p = 0.62) or between PPV and recurrence rates (Pearson Correlation 0.28; p = 0.16).

Conclusions

The simulation software shows promise in estimating the completeness of liver RFA treatment and predicting local recurrence rates, but could not be performed real-time. Future improvements in the field of registration could improve results and provide a possibility for real-time implementation.

Ultrasound-guided radiofrequency ablation enhances natural killer-mediated antitumor immunity against liver cancer

For patients with liver cancer who are not sufficiently fit for surgical resection, radiofrequency ablation (RFA) is an effective and low risk treatment modality; however, the mechanism underlying this procedure is not fully understood. In the present study, a series of experiments were conducted, which demonstrated that RFA therapy stimulates innate antitumor immunity via directly enhancing natural killer (NK) cell cytotoxicity, thus achieving a favorable outcome for patients with liver tumors. It was determined that the percentage of NK cells within the peripheral blood of the rabbits in the RFA treatment groups were significantly higher, compared with the control groups. The levels of interferon-γ and tumor necrosis factor-α in NK cells were also significantly upregulated following thermal coagulation induced via RFA. In addition, RFA enhanced the NK cell receptor, NK group 2D (NKG2D), expression and NK cell antitumor cytotoxicity in hepatic cancer cells. The results indicated that the RFA treatment could effectively eliminate liver tumors via enhancing NK-mediated antitumor activity and NKG2D expression.

Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo

BACKGROUND

The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo.

METHODS

Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry.

RESULTS

Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min.

CONCLUSIONS

Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.

Radiofrequency ablation and surgical resection of liver metastases from uveal melanoma

BACKGROUND

The resection of liver metastasis from uveal melanoma (LMUM) remains controversial. In this study, we evaluated treatment with radiofrequency ablation (RFA) for liver metastases alone or in combination with surgical liver resection.

METHODS

A total of 72 patients with LMUM were evaluated in this study. Of these, 57 patients underwent surgical resection (S) while 15 patients had RFA ± S. Clinicopathologic factors were evaluated in terms of recurrence and survival using Chi-square and log-rank tests, respectively.

RESULTS

We studied 22 metastases treated by RFA. There were no statistically significant differences between the groups in terms of median age of onset, synchronous nature of the metastases, time from primary tumour treatment to liver metastasis, diameter of the largest metastasis, presence of liver miliary disease, and the type of liver resection. There was a statistically lower number of liver metastases and more bilobar metastases in the RFA group than in the S group. The median overall survival after liver surgery was 27 months in group S and 28 months in the RFA group ± S. The median disease-free survival was 10 months in group S and 7 months in the RFA group ± S. There were no statistically significant differences in the median overall survival and disease-free survival between groups.

CONCLUSIONS

The results of this retrospective analysis show that RFA can be used to treat liver metastases to spare the hepatic parenchyma. RFA ± liver surgery and liver surgery alone demonstrate similar survival times.

Ex Vivo Liver Experiment of Hydrochloric Acid-Infused and Saline-Infused Monopolar Radiofrequency Ablation: Better Outcomes in Temperature, Energy, and Coagulation

OBJECTIVE

To compare temperature, energy, and coagulation between hydrochloric acid-infused radiofrequency ablation (HAIRFA) and normal saline-infused radiofrequency ablation (NSIRFA) in ex vivo porcine liver model.

MATERIALS AND METHODS

30 fresh porcine livers were excised in 60 lesions, 30 with HAIRFA and the other 30 with NSIRFA. Both modalities used monopolar perfusion electrode connected to a RF generator set at 103 °C and 30 W. In each group, ablation time was set at 10, 20, or 30 min (10 lesions from each group at each time). We compared tissue temperatures (at 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 cm away from the electrode tip), average power, deposited energy, deposited energy per coagulation volume (DEV), coagulation diameters, coagulative volume, and spherical ratio between the two groups.

RESULTS

Temperature-time curves showed that HAIRFA provided progressively greater heating than that of NSIRFA. At 30 min, mean average power, deposited energy, coagulation volumes (113.67 vs. 12.28 cm(3)) and diameters, and increasing in tissue temperature were much greater with HAIRFA (P < 0.001 for all), except DEV was lower (456 vs. 1396 J/cm(3), P < 0.001). The spherical ratio was closer to 1 with HAIRFA (1.23 vs. 1.46). Coagulation diameters, volume, and average power of HAIRFA increased significantly with longer ablation times. While with NSIRFA, these characteristics were stable till later 20 min, except the power decreased with longer ablation times.

CONCLUSIONS

HAIRFA creates much larger and more spherical lesions by increasing overall energy deposition, modulating thermal conductivity, and transferring heat during ablation.