Long-term outcome of Stereotactic Body Radiation Therapy for patient with unresectable liver metastases from colorectal cancer

Radiotherapy as a metastasis directed therapy for liver oligometastases - comparative analysis between CT-guided interstitial HDR brachytherapy and two SBRT modalities performed on double-layer and single layer LINACs

Introduction

Surgical resection is gold standard for treatment of liver metastasis, locally ablative techniques including computer tomography (CT)-guided interstitial high-dose-rate (HDR) brachytherapy (CT-BRT) and stereotactic body radiotherapy (SBRT) have gained prominence as alternatives, offering comparable outcomes in selected patients. We aim to compare CT-BRT and SBRT - based on dosimetric analysis.

Material and methods

Patients who underwent CT-BRT for oligometastatic, ≤4cm liver metastases between 2018 and 2024 were eligible. SBRT plans for Halcyon (SBRTh) and TrueBeam (SBRTtb) were prepared virtually. In the CT-BRT group CTV was equal to PTV, for SBRTh and SBRTtb planning, a 5 mm margin was applied to CTV to create PTV. Dose calculation was carried out with the TG-43 algorithm for CT-BRT and Anisotropic Analytical Algorithm for SBRTh and SBRTtb group. Descriptive statistics were used to compare the data. The Wilcoxon pairwise order test was utilized to compare dependent groups.

Results

CT-BRT resulted in a more favorable dose distribution within PTVs for Dmean, D50, and D90, while SBRT showed better results for D98 and V27.5Gy. No significant differences were observed for V25Gy between CT-BRT and SBRTtb, but SBRTh favored over CT-BRT. For OARs, CT-BRT plans showed better values for V5, V10, and V11.6Gy in the uninvolved liver volume. There were no significant differences in dose distribution for the duodenum, bowel, and heart. SBRT modalities performed better in the kidney. CT-BRT had improved dose distribution in the esophagus, great vessels, ribs, skin, spinal cord, and stomach compared to SBRT.

Conclusions

CT-BRT could be a viable alternative to SBRT for certain patients with liver malignancies.

Colorectal cancer: a comprehensive review of carcinogenesis, diagnosis, and novel strategies for classified treatments

Colorectal cancer is the third most common and the second deadliest cancer worldwide. To date, colorectal cancer becomes one of the most important challenges of the health system in many countries. Since the clinical symptoms of this cancer appear in the final stages of the disease and there is a significant golden time between the formation of polyps and the onset of cancer, early diagnosis can play a significant role in reducing mortality. Today, in addition to colonoscopy, minimally invasive methods such as liquid biopsy have received much attention. The treatment of this complex disease has been mostly based on traditional treatments including surgery, radiotherapy, and chemotherapy; the high mortality rate indicates a lack of success for current treatment methods. Moreover, disease recurrence is another problem of traditional treatments. Recently, new approaches such as targeted therapy, immunotherapy, and nanomedicine have opened new doors for cancer treatment, some of which have already entered the market, and many methods have shown promising results in clinical trials. The success of immunotherapy in the treatment of refractory disease, the introduction of these methods into neoadjuvant therapy, and the successful results in tumor shrinkage without surgery have made immunotherapy a tough competitor for conventional treatments. It seems that the combination of those methods with such targeted therapies will go through promising changes in the future of colorectal cancer treatment.

4D-MRI assisted stereotactic body radiation therapy for unresectable colorectal cancer liver metastases

This study evaluated the feasibilities and outcomes following four-dimensional magnetic resonance imaging (4D-MRI) assisted stereotactic body radiation therapy (SBRT) for unresectable colorectal liver metastases (CRLMs). From March 2018 to January 2022, we identified 76 unresectable CRLMs patients with 123 lesions who received 4D-MRI guided SBRT in our institution. 4D-MRI simulation with or without abdominal compression was conducted for all patients. The prescription dose was 50-65 Gy in 5-12 fractions. The image quality of computed tomography (CT) and MRI were compared using the Clarity Score. Clinical outcomes and toxicity profiles were evaluated. 4D-MRI improved the image quality compared with CT images (mean Clarity Score: 1.67 vs 2.88, P < 0.001). The abdominal compression reduced motions in cranial-caudal direction (P = 0.03) with two phase T2 weighted images assessing tumor motion. The median follow-up time was 12.5 months. For 98 lesions assessed for best response, the complete response, partial response and stable disease rate were 57.1 %, 30.6 % and 12.2 %, respectively. The local control (LC) rate at 1 year was 97.3 %. 46.1 % of patients experienced grade 1-2 toxicities and only 2.6 % patients experienced grade 3 hematologic toxicities. The 4D-MRI technique allowed accurate target delineation and motion tracking in unresectable CRLMs patients. Favorable LC rate and mild toxicities were achieved. This study provided evidence for using 4D-MRI assisted SBRT as an alternative treatment in unresectable CRLMs.

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.

The evolving role of radiation therapy as treatment for liver metastases

Liver metastases occur commonly in many solid malignancies. With advances in systemic therapies and increased life expectancy, the role of using local therapies in oligo-metastases is rapidly increasing. Stereotactic body radiotherapy (SBRT) is an emerging precision therapy that is being used more frequently in the treatment for unresectable liver metastases. This review focuses on the role of SBRT for liver metastases, principles of treatment, clinical outcomes, toxicity, and optimal patient selection.