Radiofrequency Ablation versus Stereotactic Body Radiation Therapy in the Treatment of Colorectal Cancer Liver Metastases

Treatment of Oligometastatic GI Cancers

Oligometastatic state is believed to potentially represent a transitional stage between early, locoregional state disease and widely metastatic disease. Historically, locoregional approaches, particularly in advanced colorectal cancers, have demonstrated efficacy in select patients with limited burden of metastatic disease. Recent strides in systemic therapies, including biomarker-based treatments and immunotherapy, alongside innovations in surgical techniques and novel locoregional approaches such as stereotactic radiotherapy and ablation, have ushered in a new era of therapeutic possibilities across all oligometastatic GI cancers. Despite these advancements, there remains a significant gap in high-quality prospective evidence guiding patient selection and treatment decisions across various disease types. Ongoing clinical trials are anticipated to provide crucial insights into oligometastatic states, fostering the refinement of disease-specific oligometastatic state definitions and treatment algorithms. This article reviews existing data on the management of oligometastatic GI cancer, summarizes current state of knowledge for each disease state, and provides updates on ongoing studies in this space.

Recent trends in radiotherapy use for major cancers in Korea

BACKGROUND

Although the trend in radiotherapy in all cancer patients has been studied, changes in radiotherapy modalities for specific cancer types have not been reported. This study aimed to analyze radiotherapy patterns for major cancers in Korea in recent years.

MATERIALS AND METHODS

We collected data from claims and reimbursement records of the Health and Insurance Review and Assessment Service from 2017 to 2020, according to initial diagnostic codes. The radiotherapy modalities for major cancers, such as lung, stomach, colorectal, breast and liver cancer, were analyzed. The radiotherapy modalities consisted of two-dimensional radiotherapy, three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, proton radiotherapy and stereotactic body radiotherapy.

RESULTS

Overall, from 2017 to 2020, the use of two-dimensional radiotherapy and three-dimensional conformal radiotherapy decreased, and intensity-modulated radiotherapy increased. In 2017, three-dimensional conformal radiotherapy accounted for approximately half of the radiotherapy in patients for lung and colorectal cancer, which was replaced by intensity-modulated radiotherapy in 2020. In 2020, stereotactic body radiotherapy also accounted for a large proportion of radiotherapy used in liver cancer cases. Intensity-modulated radiotherapy was most used, followed by three-dimensional conformal radiotherapy and two-dimensional radiotherapy for breast cancer in 2020. Among major cancers, radiotherapy utilization for breast cancer is the highest. Compared with other cancers, the number of patients receiving radiotherapy for stomach cancer was low.

CONCLUSION

The number of patients receiving radiotherapy for major cancers has increased. The use of advanced forms of radiotherapy, such as intensity-modulated radiotherapy, is rapidly increasing for major cancers. The rate of radiotherapy utilization was higher in major cancer patients than in all cancer patients.

Local Control Following Stereotactic Body Radiation Therapy for Liver Oligometastases: Lessons from a Quarter Century

The utilization of stereotactic body radiation therapy for the treatment of liver metastasis has been widely studied and has demonstrated favorable local control outcomes. However, several predictive factors play a crucial role in the efficacy of stereotactic body radiation therapy, such as the number and size (volume) of metastatic liver lesions, the primary tumor site (histology), molecular biomarkers (e.g., KRAS and TP53 mutation), the use of systemic therapy prior to SBRT, the radiation dose, and the use of advanced technology and organ motion management during SBRT. These prognostic factors need to be considered when clinical trials are designed to evaluate the efficacy of SBRT for liver metastases.

Comparison of radiofrequency ablation and ablative external radiotherapy for the treatment of intrahepatic malignancies: A hybrid meta-analysis

Background & Aims

Radiofrequency ablation (RFA) and ablative external beam radiotherapy (ablative RT) are commonly used to treat small intrahepatic malignancies. We meta-analysed oncologic outcomes and systematically reviewed the clinical consideration of tumour location and size.

Methods

PubMed, Medline, Embase, and Cochrane Library databases were searched on February 24, 2022. Studies comparing RFA and ablative RT, providing one of the endpoints (local control or survival), and encompassing ≥5 patients in each arm were included.

Results

Twenty-one studies involving 4,638 patients were included. Regarding survival, the odds ratio (OR) was 1.204 (p = 0.194, favouring RFA, not statistically significant) among all studies, 1.253 (p = 0.153) among hepatocellular carcinoma (HCC) studies, and 1.002 (p = 0.996) among colorectal cancer metastasis studies. Regarding local control, the OR was 0.458 (p <0.001, favouring ablative RT) among all studies, 0.452 (p <0.001) among HCC studies, favouring the ablative RT arm, and 0.649 (p = 0.484) among colorectal cancer metastasis studies. Pooled 1- and 2-year survival rates for HCC studies were 91.8% and 77.7% after RFA, and 89.0% and 76.0% after ablative RT, respectively; and for metastasis studies were 88.2% and 66.4% after RFA and 82.7% and 60.6% after RT, respectively. Literature analysis suggests that ablative RT can be more effective than RFA for tumours larger than 2-3 cm or for specific sublocations in the liver (e.g. subphrenic or perivascular sites), with moderate quality of evidence (reference to the grading system of the American Society for Radiation Oncology Primary Liver Cancer Clinical Guidelines). The pooled grade ≥3 complication rates were 2.9% and 2.8% in the RFA and ablative RT arms, respectively (p = 0.952).

Conclusions

Our study shows that ablative RT can yield oncologic outcomes similar to RFA, and suggests that it can be more effective for the treatment of tumours in locations where RFA is difficult to perform or for large-sized tumours.

Systematic Review Registration

This study was registered with PROSPERO (Protocol No: CRD42022332997).

Impact and implications

Radiofrequency ablation (RFA) and ablative radiotherapy (RT) are non-surgical modalities for the treatment of small intrahepatic malignancies. Ablative RT showed oncologic outcomes at least similar to those of RFA, and was more effective at specific locations (e.g. perivascular or subphrenic locations).

Evidence on percutaneous radiofrequency and microwave ablation for liver metastases over the last decade

Purpose

This review aimed to summarize the treatment outcomes of percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) for metastatic liver tumors based on the findings of published studies over the last decade.

Materials and methods

Literature describing the survival outcomes of ablation therapy for liver metastases was explored using the PubMed database on April 26, 2022, and articles published in 2012 or later were selected. The included studies met the following criteria: (i) English literature, (ii) original clinical studies, and (iii) literature describing overall survival (OS) of thermal ablation for metastatic liver tumors. All case reports and cohort studies with fewer than 20 patients and those that evaluated ablation for palliative purposes were excluded.

Results

RFA was the most commonly used method for ablation, while MWA was used in several recent studies. RFA and MWA for liver metastases from various primary tumors have been reported; however, majority of the studies focused on colorectal cancer. The local control rate by RFA and MWA varied widely among the studies, ranging approximately 50–90%. Five-year survival rates of 20–60% have been reported following ablation for colorectal liver metastases by a number of studies, and several reports of 10-year survival rates were also noted.

Conclusion

Comparative studies of local therapies for colorectal liver metastases demonstrated that RFA provides comparable survival outcomes to surgical metastasectomy and stereotactic body radiation therapy.