Reduced tumor growth with combined radiofrequency ablation and radiation therapy in a rat breast tumor model

Adjuvant holmium-166 radioembolization after radiofrequency ablation in early-stage hepatocellular carcinoma patients: a dose-finding study (HORA EST HCC trial)

PURPOSE

The aim of this study was to investigate the biodistribution of (super-)selective trans-arterial radioembolization (TARE) with holmium-166 microspheres (166Ho-MS), when administered as adjuvant therapy after RFA of HCC 2-5 cm. The objective was to establish a treatment volume absorbed dose that results in an absorbed dose of ≥ 120 Gy on the hyperemic zone around the ablation necrosis (i.e., target volume).

METHODS

In this multicenter, prospective dose-escalation study in BCLC early stage HCC patients with lesions 2-5 cm, RFA was followed by (super-)selective infusion of 166Ho-MS on day 5-10 after RFA. Dose distribution within the treatment volume was based on SPECT-CT. Cohorts of up to 10 patients were treated with an incremental dose (60 Gy, 90 Gy, 120 Gy) of 166Ho-MS to the treatment volume. The primary endpoint was to obtain a target volume dose of ≥ 120 Gy in 9/10 patients within a cohort.

RESULTS

Twelve patients were treated (male 10; median age, 66.5 years (IQR, [64.3-71.7])) with a median tumor diameter of 2.7 cm (IQR, [2.1-4.0]). At a treatment volume absorbed dose of 90 Gy, the primary endpoint was met with a median absorbed target volume dose of 138 Gy (IQR, [127-145]). No local recurrences were found within 1-year follow-up.

CONCLUSION

Adjuvant (super-)selective infusion of 166Ho-MS after RFA for the treatment of HCC can be administered safely at a dose of 90 Gy to the treatment volume while reaching a dose of ≥ 120 Gy to the target volume and may be a favorable adjuvant therapy for HCC lesions 2-5 cm.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03437382 . (registered: 19-02-2018).

Combination of Local Ablative Techniques with Radiotherapy for Primary and Recurrent Lung Cancer: A Systematic Review

In patients with early-stage or recurrent NSCLC who are unable to tolerate surgery, a benefit could derive only from a systemic therapy or another few forms of local therapy. A systematic review was performed to evaluate the feasibility and the effectiveness of radiotherapy combined with local ablative therapies in the treatment of primary and recurrent lung cancer in terms of toxicity profile and local control rate. Six studies featuring a total of 115 patients who met eligibility criteria and 119 lesions were included. Three studies evaluated lung cancer patients with a medically inoperable condition treated with image-guided local ablative therapies followed by radiotherapy: their local control rate (LC) ranged from 75% to 91.7% with only 15 patients (19.4%) reporting local recurrence after combined modality treatment. The other three studies provided a salvage option for patients with locally recurrent NSCLC after RT: the median follow-up period varied from 8.3 to 69.3 months with an LC rate ranging from 50% to 100%. The most common complications were radiation pneumonitis (9.5%) and pneumothorax (29.8%). The proposed intervention appears to be promising in terms of toxicity profile and local control rate. Further prospective studies are need to better delineate combining LTA-RT treatment benefits in this setting.

Study Protocol: Adjuvant Holmium-166 Radioembolization After Radiofrequency Ablation in Early-Stage Hepatocellular Carcinoma Patients-A Dose-Finding Study (HORA EST HCC Trial)

PURPOSE

To investigate the biodistribution of holmium-166 microspheres (¹⁶⁶Ho-MS) when administered after radiofrequency ablation (RFA) of early-stage hepatocellular carcinoma (HCC). The aim is to establish a perfused liver administration dose that results in a tumoricidal dose of holmium-166 on the hyperaemic zone around the ablation necrosis (i.e. target volume).

MATERIALS AND METHODS

This is a multicentre, prospective, dose-escalation study in HCC patients with a solitary lesion 2-5 cm, or a maximum of 3 lesions of ≤ 3 cm each. The day after RFA patients undergo angiography and cone-beam CT (CBCT) with (super)selective infusion of technetium-99 m labelled microalbumin aggregates (^99mTc-MAA). The perfused liver volume is segmented from the CBCT and ¹⁶⁶Ho-MS is administered to this treatment volume 5-10 days later. The dose of holmium-166 is escalated in a maximum of 3 patient cohorts (60 Gy, 90 Gy and 120 Gy) until the endpoint is reached. SPECT/CT is used to determine the biodistribution of holmium-166. The endpoint is met when a dose of ≥ 120 Gy has been reached on the target volume in 9/10 patients of a cohort. Secondary endpoints include toxicity, local recurrence, disease-free and overall survival.

DISCUSSION

This study aims to find the optimal administration dose of adjuvant radioembolization with ¹⁶⁶Ho-MS after RFA. Ultimately, the goal is to bring the efficacy of thermal ablation up to par with surgical resection for early-stage HCC patients.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03437382.

Theranostics in Interventional Oncology: Versatile Carriers for Diagnosis and Targeted Image-Guided Minimally Invasive Procedures

We are continuously progressing in our understanding of cancer and other diseases and learned how they can be heterogeneous among patients. Therefore, there is an increasing need for accurate characterization of diseases at the molecular level. In parallel, medical imaging and image-guided therapies are rapidly developing fields with new interventions and procedures entering constantly in clinical practice. Theranostics, a relatively new branch of medicine, refers to procedures combining diagnosis and treatment, often based on patient and disease-specific features or molecular markers. Interventional oncology which is at the convergence point of diagnosis and treatment employs several methods related to theranostics to provide minimally invasive procedures tailored to the patient characteristics. The aim is to develop more personalized procedures able to identify cancer cells, selectively reach and treat them, and to assess drug delivery and uptake in real-time in order to perform adjustments in the treatment being delivered based on obtained procedure feedback and ultimately predict response. Here, we review several interventional oncology procedures referring to the field of theranostics, and describe innovative methods that are under development as well as future directions in the field.

Equivalence of cell survival data for radiation dose and thermal dose in ablative treatments: analysis applied to essential tremor thalamotomy by focused ultrasound and gamma knife

Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

Effect of thermal dose on heat shock protein expression after radio-frequency ablation with and without adjuvant nanoparticle chemotherapies

PURPOSE

The aim of this study was to evaluate the effect of different radio-frequency ablation (RFA) thermal doses on coagulation and heat shock protein (HSP) response with and without adjuvant nanotherapies.

MATERIALS AND METHODS

First, Fischer rats were assigned to nine different thermal doses of hepatic RFA (50-90 °C, 2-20 min, three per group) or no treatment (n = 3). Next, five of these RF thermal doses were combined with liposomal-doxorubicin (Lipo-Dox, 1 mg intravenously) in R3230 breast tumours, or no tumour treatment (five per group). Finally, RFA/Lipo-Dox was given without and with an Hsp70 inhibitor, micellar quercetin (Mic-Qu, 0.3 mg intravenously) for two different RFA doses with similar coagulation but differing peri-ablational Hsp70 (RFA/Lipo-Dox at 70 °C × 5 min and 90 °C × 2 min, single tumours, five per group). All animals were sacrificed 24 h post-RFA and gross tissue coagulation and Hsp70 (maximum rim thickness and % cell positivity) were correlated to thermal dose including cumulative equivalent minutes at 43 °C (CEM₄₃).

RESULTS

Incremental increases in thermal dose (CEM₄₃) correlated to increasing liver tissue coagulation (R² = 0.7), but not with peri-ablational Hsp70 expression (R² = 0.14). Similarly, increasing thermal dose correlated to increasing R3230 tumour coagulation for RF alone and RFA/Lipo-Dox (R² = 0.7 for both). The addition of Lipo-Dox better correlated to increasing Hsp70 expression compared to RFA alone (RFA: R² = 0.4, RFA/Lipo-Dox: R² = 0.7). Finally, addition of Mic-Qu to two thermal doses combined with Lipo-Dox resulted in greater tumour coagulation (p < 0.0003) for RFA at 90 °C × 2 min (i.e. greater baseline Hsp70 expression) than an RFA dose that produced similar coagulation but less HSP expression (p < 0.0004).

CONCLUSION

Adjuvant intravenous Lipo-Dox increases peri-ablational Hsp70 expression in a thermally dependent manner. Such expression can be exploited to produce greater tumour destruction when adding a second adjuvant nanodrug (Mic-Qu) to suppress peri-ablational HSP expression.

A review of radiofrequency ablation: Large target tissue necrosis and mathematical modelling

Radiofrequency ablation (RFA) is an effective clinical method for tumour ablation with minimum intrusiveness. However, the use of RFA is mostly restricted to small tumours, especially those <3cm in diameter. This paper discusses the state-of-the-art of RFA, drawn from experimental and clinical results, for large tumours (i.e. ⩾3cm in diameter). In particular, the paper analyses clinical results related to target tissue necrosis (TTN) and mathematical modelling of the RFA procedure to understand the mechanism whereby the TTN is limited to under 3cm with RFA. This paper also discusses a strategy of controlling of the temperature of target tissue in the RFA procedure with the state-of-art device, which has the potential to increase the size of TTN. This paper ends with a discussion of some future ideas to solve the so-called 3-cm problem with RFA.

Clinical experiences with microwave thermal ablation of lung malignancies

Approximately 30% of early stage lung cancer patients are not surgical candidates due to medical co-morbidities, poor cardiopulmonary function and advanced age. These patients are traditionally offered chemotherapy and radiation, which have shown relatively modest improvements in mortality. For over a decade, percutaneous image-guided ablation has emerged as a safe, cost-effective, minimally invasive treatment alternative for patients who would otherwise not qualify for surgery. Although radiofrequency ablation (RFA) is currently the most extensively studied and widely utilised technique in the treatment of lung malignancies, there is a growing body of evidence that microwave ablation (MWA) has several unique benefits over RFA and cryoablation in the lung. This article reviews our institution's clinical experiences in the treatment of lung malignancies with MWA including patient selection, procedural technique, imaging follow-up, treatment outcomes and comparison of ablation techniques.

Heat shock protein inhibitor, quercetin, as a novel adjuvant agent to improve radiofrequency ablation-induced tumor destruction and its molecular mechanism

BACKGROUND

We investigated the effect of a small molecular inhibitor of heat shock protein (HSP), quercetin, on tumor radiofrequency (RF) ablation, and explored the underlying molecular mechanisms.

METHODS

In in vivo study, rats with R3230 breast adenocarcinoma were sacrificed 24 h post-treatment and gross coagulation areas were compared, and next, randomized into four treatment arms (control, quercetin alone, RF alone, and combination) for Kaplan-Meier analysis of defined endpoint survival. Then the distribution and expression levels of heat shock protein 70 (HSP70), cleaved caspase-3 and heat shock factor 1 (HSF1) were analyzed after different treatments. In in vitro study, we used quercetin to promote SK-HEP-1 (hepatic) and MCF-7 (breast) cancer cell apoptosis in heat shock cell model, and siRNA was used to block c-Jun and to explore the role of activating protein-1 (AP-1) signaling pathways.

RESULTS

We found the effects of quercetin plus RFA resulted in increase on the tumor destruction/endpoint survival (26.5±3.4 d) in vivo, compared with RF alone (17.6±2.5 d) and quercetin alone (15.7±3.1 d). Most importantly, quercetin-induced cancer cell death required the presence of HSF1 in animal model. Furthermore, quercetin directly down-regulated expression of HSF1 in vitro, which our findings have revealed, required the activation of AP-1 signaling pathways by loss-of-function analysis using siRNA mediated targeting of c-Jun.

CONCLUSIONS

These results indicated a protective role of quercetin in tumor ablation and highlighted a novel mechanism involving HSP70 with HSF1 pathway in thermal ablation of solid tumors.

Treatment of Solitary Painful Osseous Metastases with Radiotherapy, Cryoablation or Combined Therapy: Propensity Matching Analysis in 175 Patients

PURPOSE

aim of this study was to identify outcomes in pain relief and quality of life in patients with a solitary painful osseous metastasis treated by radiotherapy, cryoablation or the combination using a propensity score matching study design.

MATERIALS AND METHODS

175 patients with painful bone metastases were included in the study. Twenty-five of them underwent a radiation course (20 Gy in five daily fractions) 15 days after the cryoablation. These subjects were retrospectively matched by propensity analysis with a group of subjects treated by radiotherapy (125 subjects) and with a group treated byCryoablation (25 subjects). The pain relief in terms of complete response, rate of subjects requiring analgesics after treatments and the changes in self-rated quality of life were measured. Informed consent was obtained from the subject and the study was approved by the local Ethical Committee.

RESULTS

An higher proportion of subjects treated by cryoablation (32%) or cryoablation followed by RT (72%;) experienced a complete response compared with patients treated by radiotherapy alone (11.2%). After Bonferroni correction strategy, the addition of radiotherapy to cryoablation significantly improved the rate of complete response compared with cryoablation alone (p = 0.011) and this paralleled with an improved self-rated quality of life. Seventeen subjects (13.6%) of patients in the radiotherapy group, 9 (36%) in the cryoablation group, and 19 (76)% in the cryoablation- radiotherapy group did not require narcotic medications.

CONCLUSIONS

The addition of radiotherapy to cryoablation favorably impacts on perceived pain, with a favorable toxicity profile. However, our data should be interpreted with caution and could serve as a framework around which to design future trials.

Tumour eradication using synchronous thermal ablation and Hsp90 chemotherapy with protein engineered triblock biopolymer-geldanamycin conjugates

PURPOSE

Hepatocellular carcinoma (HCC) suffers high tumour recurrence rate after thermal ablation. Heat shock protein 90 (Hsp90) induced post-ablation is critical for tumour survival and progression. A combination therapy of thermal ablation and polymer conjugated Hsp90 chemotherapy was designed and evaluated for complete tumour eradication of HCC.

MATERIALS AND METHODS

A thermo-responsive, elastin-like polypeptide (ELP)-based tri-block biopolymer was developed and conjugated with a potent Hsp90 inhibitor, geldanamycin (GA). The anti-cancer efficacy of conjugates was evaluated in HCC cell cultures with and without hyperthermia (43 °C). The conjugates were also administered twice weekly in a murine HCC model as a single treatment or in combination with single electrocautery as the ablation method.

RESULTS

ELP-GA conjugates displayed enhanced cytotoxicity in vitro and effective heat shock inhibition under hyperthermia. The conjugates alone significantly slowed the tumour growth without systemic toxicity. Four doses of thermo-responsive ELP-GA conjugates with concomitant simple electrocautery accomplished significant Hsp90 inhibition and sustained tumour suppression.

CONCLUSION

Hsp90 inhibition plays a key role in preventing the recurrence of HCC, and the combination of ablation with targeted therapy holds great potential to improve prognosis and survival of HCC patients.

Percutaneous strategies for the management of pulmonary parenchymal, chest wall, and pleural metastases

OBJECTIVE

The purposes of this article are to review the indications for and technical aspects of various percutaneous strategies available for the treatment of intrathoracic metastases involving the parenchyma, pleura, and chest wall and to describe the relative merits of one of these strategies over another to determine the best approach to use.

CONCLUSION

The thorax is a common site of metastatic disease with frequent involvement of the lungs, pleura, and osseous structures. A variety of interventional procedures and techniques are available for treatment and for palliative care of patients with this disease. Imaging-guided interventions include thermal ablation of metastatic disease of the lungs and pleura, catheter placement and sclerosis of malignant pleural effusions, and palliative pain management for osseous and soft-tissue metastases.

Thermal ablation of tumours: biological mechanisms and advances in therapy

Minimally invasive thermal ablation of tumours has become common since the advent of modern imaging. From the ablation of small, unresectable tumours to experimental therapies, percutaneous radiofrequency ablation, microwave ablation, cryoablation and irreversible electroporation have an increasing role in the treatment of solid neoplasms. This Opinion article examines the mechanisms of tumour cell death that are induced by the most common thermoablative techniques and discusses the rapidly developing areas of research in the field, including combinatorial ablation and immunotherapy, synergy with conventional chemotherapy and radiation, and the development of a new ablation modality in irreversible electroporation.

Image-guided thermal ablation of lung malignancies

Primary and secondary lung malignancies are often treated with surgery. Many patients are poor surgical candidates owing to advanced age or medical comorbidities. Alternatives to surgery for localized disease include radiation therapy and the newer treatments known as image-guided thermal ablation. Image-guided thermal ablation involves the use of needlelike applicators that are placed directly into tumors by using imaging guidance. Tumors are destroyed by the application of either intense heat or cold. The specific ablative modalities of radiofrequency ablation, microwave ablation, laser ablation, and cryoablation are reviewed with respect to the various clinical indications for treatment of both primary and secondary lung malignancies.

Combination radiofrequency (RF) ablation and IV liposomal heat shock protein suppression: reduced tumor growth and increased animal endpoint survival in a small animal tumor model

BACKGROUND

To investigate the effect of IV liposomal quercetin (a known down-regulator of heat shock proteins) alone and with liposomal doxorubicin on tumor growth and end-point survival when combined with radiofrequency (RF) tumor ablation in a rat tumor model.

METHODS

Solitary subcutaneous R3230 mammary adenocarcinoma tumors (1.3-1.5 cm) were implanted in 48 female Fischer rats. Initially, 32 tumors (n=8, each group) were randomized into four experimental groups: (a) conventional monopolar RF alone (70°C for 5 min), (b) IV liposomal quercetin alone (1 mg/kg), (c) IV liposomal quercetin followed 24hr later with RF, and (d) no treatment. Next, 16 additional tumors were randomized into two groups (n=8, each) that received a combined RF and liposomal doxorubicin (15 min post-RF, 8 mg/kg) either with or without liposomal quercetin. Kaplan-Meier survival analysis was performed using a tumor diameter of 3.0 cm as the defined survival endpoint.

RESULTS

Differences in endpoint survival and tumor doubling time among the groups were highly significant (P<0.001). Endpoint survivals were 12.5±2.2 days for the control group, 16.6±2.9 days for tumors treated with RF alone, 15.5±2.1 days for tumors treated with liposomal quercetin alone, and 22.0±3.9 days with combined RF and quercetin. Additionally, combination quercetin/RF/doxorubicin therapy resulted in the longest survival (48.3±20.4 days), followed by RF/doxorubicin (29.9±3.8 days).

CONCLUSIONS

IV liposomal quercetin in combination with RF ablation reduces tumor growth rates and improves animal endpoint survival. Further increases in endpoint survival can be seen by adding an additional anti-tumor adjuvant agent liposomal doxorubicin. This suggests that targeting several post-ablation processes with multi-drug nanotherapies can increase overall ablation efficacy.

Synergy in cancer treatment between liposomal chemotherapeutics and thermal ablation

Minimally invasive image-guided tumor ablation using short duration heating via needle-like applicators using energies such as radiofrequency or microwave has seen increasing clinical use to treat focal liver, renal, breast, bone, and lung tumors. Potential benefits of this thermal therapy include reduced morbidity and mortality compared to standard surgical resection and ability to treat non-surgical patients. However, improvements to this technique are required as achieving complete ablation in many cases can be challenging particularly at margins of tumors>3 cm in diameter and adjacent to blood vessels. Thus, one very promising strategy has been to combine thermal tumor ablation with adjuvant nanoparticle-based chemotherapy agents to improve efficiency. Here, we will primarily review principles of thermal ablation to provide a framework for understanding the mechanisms of combination therapy, and review the studies on combination therapy, including presenting preliminary data on the role of such variables as nanoparticle size and thermal dose on improving combination therapy outcome. We will discuss how thermal ablation can also be used to improve overall intratumoral drug accumulation and nanoparticle content release. Finally, in this article we will further describe the appealing off-shoot approach of utilizing thermal ablation techniques not as the primary treatment, but rather, as a means to improve efficiency of intratumoral nanoparticle drug delivery.

Radiofrequency ablation combined with liposomal quercetin to increase tumour destruction by modulation of heat shock protein production in a small animal model

PURPOSE

To investigate the effect of heat shock protein (HSP) modulation on tumour coagulation by combining radiofrequency (RF) ablation with adjuvant liposomal quercetin and/or doxorubicin in a rat tumour model.

METHODS

Sixty R3230 breast adenocarcinoma tumours/animals were used in this IACUC-approved study. Initially, 60 tumours (n=6, each subgroup) were randomised into five groups: (1) RF alone, (2) intravenous (IV) liposomal quercetin alone (1 mg/kg), (3) IV liposomal quercetin followed 24 h later with RF, (4) RF followed 15 min later by IV liposomal doxorubicin (8 mg/kg), (5) IV liposomal quercetin 24 h before RF followed by IV liposomal doxorubicin 15 min post-ablation. Animals were sacrificed 4 or 24 h post-treatment and gross coagulation diameters were compared. Next, immunohistochemistry staining was performed for Hsp70 and cleaved caspase-3 expression. Comparisons were performed by using Student t-tests or ANOVA.

RESULTS

Combination RF-quercetin significantly increased coagulation size compared with either RF or liposomal quercetin alone (13.1±0.7 mm vs. 8.8±1.2 mm or 2.3±1.3 mm, respectively, P<0.001 for all comparisons). Triple therapy (quercetin-RF-doxorubicin) showed larger coagulation diameter (14.5±1.0 mm) at 24 h than quercetin-RF (P=0.016) or RF-doxorubicin (13.2±1.3 mm, P=0.042). Combination quercetin-RF decreased Hsp70 expression compared with RF alone at both 4 h (percentage of stained cells/hpf 22.4±13.9% vs. 38.8±16.1%, P<0.03) and 24 h (45.2±10.5% vs. 81.1±3.6%, P<0.001). Quercetin-RF increased cleaved caspase-3 expression at both 4 h (percentage of stained cells/hpf 50.7±13.4% vs. 41.9±15.1%, P<0.03) and 24 h (37.4±7.8% vs. 33.2±6.5%, P=0.045); with, triple therapy (quercetin-RF-doxorubicin) resulting in the highest levels of apoptosis (45.1±10.7%) at 24 h. Similar trends were observed for rim thickness.

CONCLUSIONS

Suppression of HSP production using adjuvant liposomal quercetin can increase apoptosis and improve RF ablation-induced tumour destruction. Further increases in tumour coagulation can be seen including an additional anti-tumour adjuvant agent such as liposomal doxorubicin.

Chemoradionuclide therapy with 186Re-labeled liposomal doxorubicin in combination with radiofrequency ablation for effective treatment of head and neck cancer in a nude rat tumor xenograft model

PURPOSE

To determine the therapeutic efficacy of rhenium 186 ((186)Re)-labeled PEGylated liposomal doxorubicin ((186)Re-liposomal doxorubicin) in combination with radiofrequency (RF) ablation of human head and neck squamous cell carcinoma (HNSCC) xenograft in nude rats.

MATERIALS AND METHODS

This investigation was approved by the animal care committee. Sixty nude rats with subcutaneously implanted HNSCC xenografts (six per group) were treated with (a) RF ablation (70 °C for 5 minutes), (b) PEGylated liposomes, (c) liposomal doxorubicin, (d) (186)Re-PEGylated liposomes (1295 MBq/kg), (e) (186)Re-liposomal doxorubicin (555 MBq/kg), (f) PEGylated liposomes plus RF ablation, (g) liposomal doxorubicin plus RF ablation, (h) (186)Re-PEGylated liposomes plus RF ablation, or (i) (186)Re-liposomal doxorubicin plus RF ablation. Six rats did not receive any treatment (control group). Tumor uptake in (186)Re therapy groups was monitored with small-animal single photon emission computed tomography for 5 days. Therapeutic efficacy was monitored for 6 weeks with measurement of tumor volume, calculation of the percentage injected dose of fluorine 18 fluorodeoxyglucose (FDG) in tumor from small-animal positron emission tomography (PET) images, and determination of viable tumor volume at histopathologic examination. Significant differences between groups were determined with analysis of variance.

RESULTS

The average tumor volume (± standard deviation) on the day of therapy was 1.32 cm(3) ± 0.17. At 6 weeks after therapy, control of tumor growth was better with (186)Re-liposomal doxorubicin than with liposomal doxorubicin alone (tumor volume, 2.26 cm(3) ± 0.89 vs 5.43 cm(3) ± 0.93, respectively; P < .01). The use of RF ablation with liposomal doxorubicin and (186)Re-liposomal doxorubicin further improved tumor control (tumor volume, 2.05 cm(3) ± 1.36 and 1.49 cm(3) ± 1.47, respectively). The tumor growth trend correlated with change in percentage of injected dose of FDG in tumor for all groups (R(2) = 0.85, P < .001). Viable tumor volume was significantly decreased in the group treated with (186)Re-liposomal doxorubicin plus RF ablation (0.54 cm(3) ± 0.38; P < .001 vs all groups except (186)Re-liposomal doxorubicin alone).

CONCLUSION

Triple and dual therapies had an observable trend ((186)Re-liposomal doxorubicin plus RF ablation > (186)Re-liposomal doxorubicin > liposomal doxorubicin plus RF ablation > liposomal doxorubicin) of improved tumor growth control and decreased viable tumor compared with other therapies. FDG PET could be used as a noninvasive surrogate marker for tumor growth and viability in this tumor model.

Thermal ablation of lung tumors

The 5-year survival for all stages of nonsmall cell lung cancer (NSCLC) remains bleak, having increased from 13% to just 16% over the past 30 years. Despite promising results in nonoperative patients with NSCLC and pulmonary metastatic disease, thermal ablation appears to be limited by large tumor size and proximity to large vessels. This article discusses the particular challenges of performing thermal ablation in aerated lung tissue and reviews important considerations in performing ablation including treatment complications and imaging follow-up. The article compares and contrasts the three major thermal ablation modalities: radiofrequency ablation, microwave ablation, and cryoablation.

Thermal ablation and high-temperature thermal therapy: Overview of technology and clinical implementation

High-temperature hyperthermia or thermal therapy is being applied for destruction of cancerous tissue, eradication or reduction of benign tumours and targeted tissue modification and remodelling. Many of these high-temperature technologies provide a minimally-invasive alternative with lower morbidities compared to the traditional surgical procedures. The effects of high-temperature thermal exposure on tissues, examples of heating technology and procedures of clinical practice related to high-temperature thermal therapy are reviewed. This brief review encompasses interstitial, endocavity, intraluminal and external applications of RF, microwave, ultrasound, laser and thermal conduction energy sources. The technology is prevalent and in various levels of advancement, with the move toward more spatially-accurate and controllable heating systems combined with image-guidance and treatment verification warranted, especially for the treatment of cancer.

Principles of and advances in percutaneous ablation

Image-guided tumor ablation with both thermal and nonthermal sources has received substantial attention for the treatment of many focal malignancies. Increasing interest has been accompanied by continual advances in energy delivery, application technique, and therapeutic combinations with the intent to improve the efficacy and/or specificity of ablative therapies. This review outlines clinical percutaneous tumor ablation technology, detailing the science, devices, techniques, technical obstacles, current trends, and future goals in percutaneous tumor ablation. Methods such as chemical ablation, cryoablation, high-temperature ablation (radiofrequency, microwave, laser, and ultrasound), and irreversible electroporation will be discussed. Advances in technique will also be covered, including combination therapies, tissue property modulation, and the role of computer modeling for treatment optimization.

Do liposomal apoptotic enhancers increase tumor coagulation and end-point survival in percutaneous radiofrequency ablation of tumors in a rat tumor model?

PURPOSE

To characterize effects of combining radiofrequency (RF) ablation with proapoptotic intravenous liposome-encapsulated paclitaxel and doxorubicin on tumor destruction, apoptosis and heat-shock protein (HSP) production, intratumoral drug accumulation, and end-point survival.

MATERIALS AND METHODS

R3230 mammary adenocarcinomas (n = 177) were implanted in 174 rats in this animal care committee-approved study. Tumors received (a) no treatment, (b) RF ablation, (c) paclitaxel, (d) RF ablation followed by paclitaxel (RF ablation-paclitaxel), (e) paclitaxel before RF ablation (paclitaxel-RF ablation), (f) RF ablation followed by doxorubicin (RF ablation-doxorubicin), (g) paclitaxel followed by doxorubicin without RF ablation (paclitaxel-doxorubicin), or (h) paclitaxel before RF ablation, followed by doxorubicin (paclitaxel-RF ablation-doxorubicin). Tumor coagulation area and diameter were compared at 24-96 hours after treatment. Intratumoral paclitaxel uptake with and without RF ablation were compared. Immunohistochemical staining revealed cleaved caspase-3 and 70-kDa HSP (HSP70) expression. Tumors were randomized into eight treatment arms for Kaplan-Meier analysis of defined survival end-point (3.0-cm diameter).

RESULTS

Paclitaxel-RF ablation increased tumor coagulation over RF ablation or paclitaxel (mean, 14.0 mm ± 0.9 [standard deviation], 6.7 mm ± 0.6, 2.5 mm ± 0.6, respectively; P < .001). Paclitaxel-RF ablation-doxorubicin had similar tumor coagulation (P < .05), compared with paclitaxel-RF ablation, at 24 and 96 hours. Mean intratumoral paclitaxel accumulation for paclitaxel-RF ablation (6.76 μg/g ± 0.35) and RF ablation-paclitaxel (9.28 μg/g ± 0.87) increased over that for paclitaxel (0.63 μg/g ± 0.25, P < .001). Paclitaxel substantially increased apoptosis and decreased HSP70 expression at coagulation margin. Mean end-point survival for paclitaxel-RF ablation-doxorubicin (56.8 days ± 25.3) was greater, compared with that for paclitaxel-RF ablation or RF ablation-paclitaxel (17.6 days ± 2.5), RF ablation-doxorubicin (30.3 days ± 4.9, P < .002), or paclitaxel-doxorubicin (27.9 days ± 4.1, P < .001).

CONCLUSION

Selecting adjuvant liposomal chemotherapies (paclitaxel, doxorubicin) to target cellular apoptosis and HSP production effectively increases RF ablation-induced tumor coagulation and end-point survival, and combined multidrug approach results in even better outcomes.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100500/-/DC1.

Today's thermal therapy: not your father's hyperthermia: challenges and opportunities in application of hyperthermia for the 21st century cancer patient

The realization that hyperthermia was an ideal complementary treatment to radiation and certain chemotherapeutic agents from a biologic perspective led to great enthusiasm for this modality over a quarter of a century ago. Unfortunately, this well-deserved enthusiasm quickly become tempered because of the inability to effectively heat tumors, particularly deep-seated ones with cumbersome first generation technology coupled with still-emerging understandings of thermal biology. Today as before, both challenges and opportunities remain in the application of hyperthermia for cancer patients. The lessons learned from the introduction of hyperthermia, a generation ago, are providing focus for application of this still-promising modality in today's clinic. These areas of challenge and opportunity include: thermal biology; treatment planning, delivery, and monitoring; successful high-quality clinical trials; and integration of thermal therapy with emerging technologies and therapeutic strategies both established and evolving. The progress made in understanding of thermal biology, physics, and bioengineering, coupled with advances in complementary clinical treatment modalities have all contributed to the next generation of clinical thermal therapy.

Liposomal doxorubicin increases radiofrequency ablation-induced tumor destruction by increasing cellular oxidative and nitrative stress and accelerating apoptotic pathways

PURPOSE

To determine if oxidative and nitrative stress and/or apoptosis contribute to increased coagulation when combining radiofrequency (RF) ablation with liposomal doxorubicin.

MATERIALS AND METHODS

Animal care committee approval was obtained. R3230 mammary adenocarcinomas in Fischer rats were treated with either RF ablation (n = 43), 1 mg of intravenously injected liposomal doxorubicin (n = 26), or combined therapy (n = 30) and were compared with control subjects (n = 11). A subset of animals receiving combination therapy (n = 24) were treated in the presence or absence of N-acetylcysteine (NAC) administered 24 hours and 1 hour before RF ablation. Tumors were analyzed 2 minutes to 72 hours after treatment to determine the temporal range of response by using immunohistochemical staining of the apoptosis marker cleaved caspase-3, phosphorylated gammaH2AX, and HSP70 and of markers of oxidative and nitrative stress (8-hydroxydeoxyguanosine [8-OHdG], 4-hydroxynonenal [4-HNE]-modified proteins, and nitrotyrosine [NT]). Statistical analyses, including t tests and analysis of variance for comparisons where appropriate, were performed.

RESULTS

By 4 hours after RF ablation alone, a 0.48-mm +/- 0.13 (standard deviation) peripheral band with 57.0% +/- 7.3 cleaved caspase-3 positive cells was noted at the ablation margin, whereas a 0.73-mm +/- 0.18 band with 77.7% +/- 6.3 positivity was seen for combination therapy (P < .03 for both comparisons). Combination therapy caused increased and earlier staining for 4-HNE-modified proteins, 8-OHdG, NT, and gammaH2AX with colocalization to cleaved caspase-3 staining. A rim of increased HSP70 was identified peripheral to the area of cleaved caspase-3. Parameters of oxidative and nitrative stress were significantly inhibited by NAC 1 hour following RF ablation, resulting in decreased cleaved caspase-3 positivity (0.28-mm +/- 0.09 band of 25.9% +/- 7.4 positivity vs 0.59-mm +/- 0.11 band of 62.9% +/- 6.0 positivity, P < .001 for both comparisons).

CONCLUSION

Combining RF ablation with liposomal doxorubicin increases cell injury and apoptosis in the zone of increased coagulation by using a mechanism that involves oxidative and nitrative stress that leads to accelerated apoptosis.

RF ablation with adjuvant therapy: comparison of external beam radiation and liposomal doxorubicin on ablation efficacy in an animal tumor model

PURPOSE

To determine the critical thermal dosimetry and relative efficacy for RF ablation combined with external beam radiation (XRT) or liposomal doxorubicin (LD), in an animal tumor model.

MATERIALS AND METHODS

This study was performed in two phases, in 13-18 mm diameter R3230 tumors subcutaneously implanted into Fischer rats. In phase 1, tumors (n = 30) were randomized into six groups. RF energy (titrated to 70 degrees C tip temperature) was applied for either 2.5 or 5 min (n = 15, each group). For each duration, one of three adjuvant therapies was applied (n = 5, each): no therapy (control), LD (1 mg intravenously, 30 min post-RF), or XRT (20 Gy at 1 Gy min(-1), within 2 h post-RF), with sacrifice at 48 h for pathologic analysis. In phase 2, thermal mapping was performed in 20 tumors throughout RF application (70 degrees C; 5 min), at 1.5-7 mm distances from the active electrode tip. Temperature profiles throughout the tumor were constructed and were used to interpolate temperatures over time at the critical ablation margin, to derive maximum threshold temperature, AUC (area under the curve) and CEM(43) (cumulative equivalent minutes at 43 degrees C). Ablation sizes and all calculated values were compared within and across experimental groups using MANOVA statistics with pair-wise T-test for individual comparisons.

RESULTS

RF/XRT produced the largest coagulation (11.7 +/- 1.5 mm at 2.5 min, >or=15 +/- 0.7 mm at 5 min), followed by RF/LD, and then RF alone (p < 0.001 for all comparisons). RF/XRT demonstrated temperature threshold decreases from RF alone of 11.7 +/- 0.01 degrees C and 12.7 +/- 0.38 degrees C at 2.5 and 5 min respectively (with absolute thresholds of 42 degrees C for XRT compared to 52 degrees C for RF alone). RF/LD had decreases of 4.0 degrees C at 2.5 min and 4.4 degrees C at 5 min. Thermal dose requirements (AUC) decreased by 7.79% or 9.28% for RF/LD compared to >or=19.36% or 25.82% for RF/XRT at 2.5 and 5 min (p < 0.001). CEM(43) values followed similar patterns (p < 0.001), but with a reduction of 10(1) and 10(4) in magnitude for RF/LD and RF/XRT therapies at 5 min, respectively.

CONCLUSIONS

For a standardized RF dose, the combination of high dose XRT and RF increased ablation size compared to RF and liposomal doxorubicin or RF alone. Increased ablation size is more closely associated with decreased temperature threshold necessary to induce coagulation, rather than the total thermal dose.

Radiofrequency ablation in the treatment of primary breast cancer: no surgical redundancies yet

BACKGROUND/INTRODUCTION

Radiofrequency energy has emerged as a new tool for the local destruction of cancer by inducing thermal tissue necrosis in the target region. Radiofrequency ablation (RFA) has recently been used to treat breast cancer primaries, potentially offering all the advantages of minimally invasive techniques.

METHODS/EVIDENCE

Nine published studies addressing the role of RFA in the treatment of breast cancer have been identified and analysed, in six, first-line RFA was followed by surgical removal and there were 12 failures in 108 ablations. Three further studies involved RFA without subsequent excision and in 1/60 there was a local relapse after 4 months (follow-up range: 15-29 months).

DISCUSSION

Existing RFA techniques may not be able to destroy the whole of the malignant lesion, because of local conditions allowing cancer cells to survive within the target area or because electrodes cannot be accurately directed to the tumour site with ultrasound. Additionally, distant in-breast cancers can be missed on pre/intraoperative imaging. Histological information is unavailable after tissue destruction so that the opportunity to reassess tumour grade based on more extensive sampling is lost, but this can be improved by more extensive sampling with vacuum-assisted core biopsy.

CONCLUSIONS

Before RFA can be safely used in the treatment of breast cancer primaries, several criteria need to be met. These include development of RFA devices and techniques, standardisation of the treatment protocol, including imaging and selection of patients, and establishment of a feasible post-treatment follow-up strategy.

Image-guided percutaneous thermal ablation for the palliative treatment of chest wall masses

OBJECTIVES

To evaluate the palliative benefits of image-guided thermal ablation for the treatment of painful tumors affecting the chest wall.

METHODS

Thirty-nine patients, median age 65 years, underwent percutaneous thermal ablation of 44 chest wall masses. Thirty-eight radiofrequency ablations (RFAs), 3 microwave ablations (MWAs), and 3 cryoablations were performed. Subjective pain reports at 1 week and 1 month postablation were scored from 0 to 4 based on a standard Likert pain relief scale, with 2 or higher representing clinically significant pain relief.

RESULTS

Patients were followed for a median of 6 months. Overall, 31 of 44 procedures (70.5%) resulted in significant pain relief. Improvement followed 15 of 15 (100%) of ablations that were performed within 90 days of treatment with palliative external-beam radiation therapy (XRT), compared with 16 of 29 (55.2%) of the remaining procedures. Mean pain relief score at 1 month was 3.86 for the 15 combined procedures versus 1.96 for the 29 remaining procedures (P < 0.001). Local pain recurred after 5 of 31 positive responses (16.1%). Median survival was 11.2 +/- 2.3 months for patients with significant pain relief and 4.3 +/- 1.4 months for nonresponders (P < 0.001). Adverse events included a transient symptom "flare" (n = 5, 11.4%) and the exacerbation of a preexisting brachial plexopathy.

CONCLUSIONS

Thermal ablation results in significant pain relief for the majority of patients and shows evidence of synergistic benefit when temporally combined with XRT. This minimally invasive technique appears to be a safe and durable alternative for the palliation of chest wall masses.

Percutaneous radiofrequency ablation of lung tumors close to the heart or aorta: evaluation of safety and effectiveness

PURPOSE

The authors retrospectively evaluated the safety and effectiveness of percutaneous radiofrequency ablation of lung tumors close to the heart or aorta.

MATERIALS AND METHODS

Forty-two tumors (mean diameter, 25 mm +/- 16; range, 5-73 mm) located less than 10 mm from the heart or aorta were treated with radiofrequency ablation in 47 sessions. Lung tumors were classified into two groups according to their distance from the heart or aorta: group A (n = 27) comprised tumors at a distance of 1-9 mm; group B (n = 15) comprised contiguous tumors (distance, 0 mm). The safety and technique effectiveness of the procedure, defined as no evidence of local tumor progression, were evaluated.

RESULTS

Radiofrequency ablation was feasible for all the 42 tumors. Procedural complications included asymptomatic pleural effusion (n = 5), small pneumothorax (n = 11), pneumothorax that necessitated chest tube placement (n = 4), and lung abscess (n = 1). No complications related to the specific tumor location, such as the accidental insertion of the electrode into the heart or aorta, pericardial effusion, arrhythmia, or cardiac infarction, occurred. The overall primary technique effectiveness rate was 75.8%, 45.9%, and 45.9% at 6, 12, and 24 months, respectively. This rate in group A (94.7%, 69.3%, and 69.3% at 6, 12, and 24 months, respectively) was significantly (P < .001) higher than that in group B (42.9% and 8.6% at 6 and 12 months, respectively).

CONCLUSIONS

Radiofrequency ablation of lung tumors close to the heart or aorta was safely performed. The local control of tumors contiguous to the heart or aorta was considerably lower compared with the tumors that were close but not contiguous to these structures.

Role of Adjuvant Radiation (External Beam/Brachytherapy) for Stage I NSCLC

There seems to be no role for adjuvant radiation in stage I NSCLC patients treated by lobectomy. Adjuvant brachytherapy in combination with sublobar resection is a promising approach that seems to decrease local recurrence rates similar to that reported following lobectomy. If the results of the current American College of Surgeons Oncology Group randomized trial are favorable, it may be possible in the future to define subgroups of patients with stage I NSCLC who are able to be treated with this approach in preference to lobectomy. Until further data are available, lobectomy should remain the standard of care. RFA is an alternative for the high-risk patient with NSCLC who is considered too high-risk even for sublobar resection. Although long-term results are not yet available, it does seem that local recurrence is a significant problem. In a similar fashion to the approach currently being investigated with sublobar resection, the addition of radiation may improve local control after RFA. In particular, adjuvant stereotactic radiation should be investigated as a potential method of decreasing local recurrence and preserving lung function in these high-risk patients.

Radiofrequency Ablation of Normal Lungs after Pulmonary Artery Embolization with Use of Degradable Starch Microspheres: Results in a Porcine Model

PURPOSE

The present study was performed to evaluate the effect of pulmonary artery embolization on radiofrequency (RF) ablation of normal porcine lungs.

MATERIALS AND METHODS

RF ablation zones (n=34) were created in the normal lungs of five domestic pigs (five zones in each of the first two pigs and eight zones in each of the remaining three pigs) with an expandable multitined electrode with use of bilateral thoracotomy. RF ablation was performed without pulmonary artery embolization (group 1, n=8), immediately after embolization (group 2, n=11), 15 minutes after embolization (group 3, n=7), and 30 minutes after embolization (group 4, n=8) with degradable starch microspheres. Among them, 12 ablation zones were excluded from this study because they were considerably limited by the presence of the pleura or large bronchi. The remaining 22 zones were included (n=7, n=5, n=4, and n=6 in groups 1, 2, 3, and 4, respectively). Coagulation necrosis volumes in the ablation zones were measured and compared among the groups.

RESULTS

Coagulation necrosis volumes were 0.9+/-0.5 cm3, 2.1+/-0.4 cm3, 2.1+/-1.0 cm3, and 1.9+/-0.6 cm3 in groups 1, 2, 3, and 4, respectively. Groups 2-4 showed significantly larger coagulation volumes than group 1 (P=.012, P=.023, and P=.010 in groups 2, 3, and 4, respectively).

CONCLUSION

Pulmonary artery embolization contributed to larger volumes of coagulation necrosis after RF ablation of normal lungs.

Percutaneous image-guided thermal ablation and radiation therapy: outcomes of combined treatment for 41 patients with inoperable stage I/II non-small-cell lung cancer

PURPOSE

To evaluate the clinical outcomes in patients with early-stage non-small-cell lung cancer (NSCLC) after combined treatment with thermal ablation and radiation therapy (RT).

MATERIALS AND METHODS

Forty-one patients with inoperable stage I/II NSCLC tumors underwent thermal ablation and RT at our institution between 1998 and 2005. Thirty-seven radiofrequency (RF) ablation procedures and four microwave ablation procedures were performed. Ablations were followed by standard-fraction external-beam RT within 90 days (n = 27) or postprocedural brachytherapy (n = 14). Survival and local recurrence were the primary endpoints evaluated by Kaplan-Meier analysis.

RESULTS

The median follow-up was 19.5 months. The overall survival rates were 97.6% at 6 months, 86.8% at 1 year, 70.4% at 2 years, and 57.1% at 3 years. Patients with tumors smaller than 3 cm (n = 17) had an average survival time of 44.4 +/- 5.4 months (SE). Patients with tumors 3 cm or larger (n = 24) had an average survival time of 34.6 +/- 7.0 months (P = .08). Local recurrence occurred in 11.8% of tumors smaller than 3 cm after an average of 45.6 +/- 4.1 months and in 33.3% of the larger tumors after an average of 34.0 +/- 7.8 months (P = .03). Outcomes in the brachytherapy and RT groups did not differ significantly. Nine of 15 pneumothoraces required chest tube drainage (22.0%).

CONCLUSIONS

Thermal ablation followed by RT for inoperable stage I/II NSCLC has a relatively low rate of complications that are easily managed. Combined therapy may result in an improved survival compared with either modality alone.

Percutaneous Radiofrequency Ablation Combined with Previous Bronchial Arterial Chemoembolization and Followed by Radiation Therapy for Pulmonary Metastasis from Hepatocellular Carcinoma

A 56-year-old man had a lung metastasis from hepatocellular carcinoma 4.7 cm x 3.4 cm in size located directly adjacent to the pulmonary hilar vessels. The tumor was treated with radiofrequency ablation combined with earlier bronchial arterial chemoembolization and subsequent radiation therapy. A complete remission of the tumor has been observed for 6 months since completion of therapy. Considering that complete treatment of such an intermediate-sized tumor adjacent to the large vessels is usually difficult with radiofrequency ablation alone, this result suggests a possible role for combined therapy for pulmonary neoplasms.