The tolerance of gastrointestinal organs to stereotactic body radiation therapy: what do we know so far?

Exploring the Evolving Landscape of Stereotactic Body Radiation Therapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) carries significant morbidity and mortality. Management of the HCC requires a multidisciplinary approach. Surgical resection and liver transplantation are the gold standard options for the appropriate settings. Stereotactic body radiation therapy (SBRT) has emerged as a promising treatment modality in managing HCC; its use is more studied and well-established in advanced HCC (aHCC). Current clinical guidelines universally endorse SBRT as a viable alternative to radiofrequency ablation (RFA), transarterial chemoembolisation (TACE), and transarterial radioembolisation (TARE), a recommendation substantiated by literature demonstrating comparable efficacy among these modalities. In early-stage HCC, SBRT primarily manages unresectable tumours unsuitable for ablative procedures such as microwave ablation and RFA. SBRT has been incorporated as a modality to downstage tumours or as a bridge to transplant. In the case of intermediate or advanced HCC, SBRT offers excellent results either as a single modality or adjunct to other locoregional modalities such as TACE/TARE. Recent data from late-stage HCC patients illustrate the effectiveness of SBRT in achieving local tumour control while minimising damage to surrounding healthy liver tissue. It has promising local control of approximately 80-90% in managing HCC. Additional prospective data comparing the efficacy of SBRT with the first-line recommended therapies such as RFA, TACE, and surgery are essential. The standard of care for patients with advanced/metastatic disease is systemic therapy (immunotherapy/tyrosine kinase inhibitors). SBRT, in combination with immune-checkpoint inhibitors, has an immune-modulatory effect that results in a synergistic effect. Recent findings indicate that the combination of immunotherapy and SBRT in HCC is well-tolerated and exhibits synergistic effects. Further exploration of diverse immunotherapy and radiotherapy strategies is essential to identify the appropriate time for combination treatments and to optimise dose and fraction regimens. Prospective, randomised studies are imperative to establish SBRT as the primary treatment for HCC.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 4: Liver and locally recurrent rectal cancer

In this paper, we review the use of hypofractionated radiotherapy for gastrointestinal malignancies, focusing on primary and metastatic liver cancer, and recurrent rectal cancer. Technological advancements in radiotherapy have facilitated the direct delivery of high-dose radiation to tumors, while limiting normal tissue exposure, supporting the use of hypofractionation. Hypofractionated radiotherapy is particularly effective for primary and metastatic liver cancer where high-dose irradiation is crucial to achieve effective local control. For recurrent rectal cancer, the use of stereotactic body radiotherapy offers a promising approach for re-irradiation, balancing efficacy and safety in patients who have been administered previous pelvic radiotherapy and in whom salvage surgery is not applicable. Nevertheless, the potential for radiation-induced liver disease and gastrointestinal complications presents challenges when applying hypofractionation to gastrointestinal organs. Given the lack of universal consensus on hypofractionation regimens and the dose constraints for primary and metastatic liver cancer, as well as for recurrent rectal cancer, this review aims to facilitate clinical decision-making by pointing to potential regimens and dose constraints, underpinned by a comprehensive review of existing clinical studies and guidelines.

Survival and Toxicity in Patients With Unresectable or Inoperable Biliary Tract Cancers With Ablative Radiation Therapy Versus Nonablative Chemoradiation

Purpose

Conventional chemoradiation (CCRT) is inadequately effective for the treatment of unresectable or inoperable biliary tract cancers (UIBC). Ablative radiation therapy (AR), typically defined as a biologically effective dose (BED) ≥80.5 Gy, has shown some promise in terms of local control and survival in these patients. We compare the efficacy and toxicity of AR to non-AR in UIBC patients.

Methods and Materials

Patients with UIBC treated with stereotactic body radiation therapy (SBRT; n = 18) or CCRT (n = 28) between 2006 and 2021 were retrospectively analyzed. The associations of treatment, BED groups, selected characteristics with overall survival (OS), progression-free survival (PFS), and local control were estimated separately using Cox proportional hazards regression. Toxicity was scored using Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Results

Median dose fractionation was 60 Gy in 5 fractions (median BED, 127 Gy) for SBRT and 50 Gy in 25 fractions (median BED, 64 Gy) for CCRT. The median follow-up of the entire cohort was 11.5 months. The 1-year OS rate was 62% for BED <80.5 versus 66% for BED ≥80.5 (P = .069). The 1-year PFS rate was 24% for BED <80.5 and 29% for BED ≥80.5 (P = .050). The 1-year local control rate was 20% for BED <80.5 and 41% for BED ≥80.5 (P = .097). BED as a continuous variable (P = .013), BED ≥100 Gy (P = .044), and race (white versus nonwhite) (P = .037) were associated with improved overall mortality. BED ≥80.5 Gy (P = .046), smaller tumor size (<5 cm; P = .038) and N0 disease (P <.0001) were associated with improved disease progression rates. Local control was improved in patients with N0 disease compared with N1 disease (P <.0001). Both treatments were well tolerated; there was no difference in acute and late toxicity between AR and non-AR.

Conclusions

In this review, there was improved PFS with BED ≥80.5 Gy with a trend toward OS benefit. BED ≥80.5 Gy was achieved mostly through SBRT and was well tolerated. AR could be considered a more effective treatment modality than CCRT in patients with UIBC.

Retrospective study on the toxicity induced by stereotactic body radiotherapy: overview of the reunion experience on prostate cancer in elderly patients

Introduction

Prostate cancer is the fourth most commonly diagnosed cancer among men worldwide. Various tools are used to manage disease such as conventional radiotherapy. However, it has been demonstrated that large prostate volumes were often associated with higher rates of genitourinary and gastrointestinal toxicities. Currently, the improvements in radiotherapy technology have led to the development of stereotactic body radiotherapy, which delivers higher and much more accurate radiation doses. In order to complete literature data about short-term outcome and short-term toxic effects of stereotactic body radiotherapy, we aimed to share our experience about gastrointestinal and genitourinary toxicities associated with stereotactic body radiotherapy in prostate cancer in patients over 70 years old.

Methods

We retrospectively reviewed the medical records of elderly patients with prostate cancer treated between 2021 and 2022. The elderly patients were treated with a non-coplanar robotic stereotactic body radiotherapy platform using real-time tracking of implanted fiducials. The prostate, with or without part of the seminal vesicles, was treated with a total dose of 36.25 Gy delivered in five fractions, each fraction being administered every other day.

Results

We analyzed a total of 80 elderly patients, comprising 38 low-, 37 intermediate- and 5 high-risk patients. The median follow-up duration was 12 months. We did not observe biochemical/clinical recurrence, distant metastasis, or death. Grade 2 acute genitourinary toxicity was observed in 9 patients (11.25%) and Grade 2 acute gastrointestinal toxicity in 4 patients (5.0%). We did not observe any grade 3 or more acute or late toxicities.

Conclusion

Over the follow-up period, we noted a low frequency of gastrointestinal and genitourinary toxicities induced by stereotactic body radiotherapy in the context of prostate cancer in elderly patients. Therefore, stereotactic body radiotherapy seems to represent a promising treatment option for elderly patients, with acceptable acute toxicity.

Effect of stomach size on organs at risk in pancreatic stereotactic body radiotherapy

BACKGROUND

In clinical practice, the organs at risk (OARs) should be carefully determined when performing pancreatic stereotactic body radiotherapy (SBRT). We conducted a simulation study to examine the effect of the stomach size on the radiation dose to the OARs when performing pancreatic SBRT.

METHODS

Twenty-five cases were included in this study. Pancreatic head and body tumors were 2-cm-sized pseudotumors, which were included as gross target volume (GTV) contours. The stomach, pancreas, small intestine, liver, kidneys, and spinal cord were considered as the OARs. The prescription dose for planning target volume (PTV) was 40 Gy/5fx, and the dose limit for the OARs was determined. The dose to X% of the OAR volume at X values of 0.1, 5.0, and 10.0 cc (DX) and the percentage of the OAR volume that received more than X Gy were recorded.

RESULTS

In terms of the radiation dose to the pancreatic body tumors, the stomach size was positively correlated with a dose of D10cc [correlation coefficient (r) = 0.5516) to the stomach. The r value between the radiation dose to the pancreatic head tumor and the stomach size was 0.3499. The stomach size and radiation dose to the head and body of the pancreas were positively correlated (pancreatic head D10cc: r = 0.3979, pancreatic body D10cc: r = 0.3209). The larger the stomach, the larger the radiation dose to the healthy portion of the pancreas outside the PTV.

CONCLUSIONS

When performing pancreatic SBRT, the dose to the OARs depends on the stomach size. Reducing the dose to the stomach and pancreas can be achieved by shrinking the stomach.

Development of an Objective Scoring System for Endoscopic Assessment of Radiation-Induced Upper Gastrointestinal Toxicity

Simple Summary

High-dose radiation therapy techniques have gained increasing interest in pancreatic cancer treatment, but toxicity to the upper gastrointestinal (GI) organs remains a major concern. We aimed to develop an objective toxicity scoring system to be used during endoscopic evaluation that allows for direct assessment of the stomach and duodenum before and after radiation treatment. Our toxicity scoring takes into account the pathological categories of erythema, edema, ulceration, and stricture to determine radiation-related GI toxicity. We assessed and validated the upper GI toxicity of 19 locally advanced pancreatic cancer trial patients undergoing stereotactic body radiation therapy (SBRT). With future usage, we hope this scoring system will provide objective and reliable assessments of changes in GI toxicity during the radiation treatment of pancreatic cancer and for GI toxicity assessment during radiation therapy research trials.

Abstract

We developed and implemented an objective toxicity scoring system to be used during endoscopic evaluation of the upper gastrointestinal (GI) tract in order to directly assess changes in toxicity during the radiation treatment of pancreatic cancer. We assessed and validated the upper GI toxicity of 19 locally advanced pancreatic cancer trial patients undergoing stereotactic body radiation therapy (SBRT). Wilcoxon-signed rank tests were used to compare pre- and post-SBRT scores. Comparison of the toxicity scores measured before and after SBRT revealed a mild increase in toxicity in the stomach and duodenum (p < 0.005), with no cases of severe toxicity observed. Kappa and AC1 statistics analysis were used to evaluate interobserver agreement. Our toxicity scoring system was reliable in determining GI toxicity with a good overall interobserver agreement for pre-treatment scores (stomach, κ = 0.71, p < 0.005; duodenum, κ = 0.88, p < 0.005) and post-treatment scores (stomach, κ = 0.71, p < 0.005; duodenum, κ = 0.76, p < 0.005). The AC1 statistics yielded similar results. With future usage, we hope this scoring system will be a useful tool for objectively and reliably assessing changes in GI toxicity during the treatment of pancreatic cancer and for GI toxicity assessments and comparisons during radiation therapy research trials.

Stereotactic body radiotherapy delivered with IMRT for oligometastatic regional lymph node metastases in hepatocellular carcinoma: a single-institutional study

The optimal treatment to lymph node metastases in hepatocellular carcinoma (HCC) has not been established, yet. Our aim was to evaluate the local control, the survival benefit and the toxicity of stereotactic body radiotherapy (SBRT) delivered with intensity-modulated radiotherapy (IMRT) to oligometastatic regional lymph node in HCC patients. We retrospectively analyzed 15 patients with HCC treated with SBRT delivered using IMRT to 24 regional lymph node metastases. Dose prescriptions were set to 45 Gy in 6 fractions of 7.5 Gy for solitary lesions and 49.5 Gy in 9 fractions of 5.5 Gy for multiple lesions. For the planning target volume, the plan was optimized aiming for a V95% > 90%. The study endpoints were freedom from local progression (FFLP), progression-free survival (PFS), overall survival (OS) and toxicity. The median follow-up was 18.1 months. The 1-year and 2-year FFLP rates were 100 and 90 ± 9.5%, respectively. The 1-year PFS rate was 46.7 ± 12.9%, and the 1-year and 2-year OS rates were 73.3 ± 11.4 and 28.6 ± 12.7%, respectively. Only one patient had a duodenal ulcer and three patients had liver enzyme elevation in sub-acute toxicity, however there was no grade ≥ 3 toxicity. In conclusion, SBRT delivered with IMRT to lymph node metastases can offer excellent local control with minimal toxicity, and SBRT may improve HCC patients' survival more than conventional radiotherapy.

Development and evaluation of machine learning models for voxel dose predictions in online adaptive magnetic resonance guided radiation therapy

PURPOSE

Daily online adaptive plan quality in magnetic resonance imaging guided radiation therapy (MRgRT) is difficult to assess in relation to the fully optimized, high quality plans traditionally established offline. Machine learning prediction models developed in this work are capable of predicting 3D dose distributions, enabling the evaluation of online adaptive plan quality to better inform adaptive decision-making in MRgRT.

METHODS

Artificial neural networks predicted 3D dose distributions from input variables related to patient anatomy, geometry, and target/organ-at-risk relationships in over 300 treatment plans from 53 patients receiving adaptive, linac-based MRgRT for abdominal cancers. The models do not include any beam related variables such as beam angles or fluence and were optimized to balance errors related to raw dose and specific plan quality metrics used to guide daily online adaptive decisions.

RESULTS

Averaged over all plans, the dose prediction error and the absolute error were 0.1 ± 3.4 Gy (0.1 ± 6.2%) and 3.5 ± 2.4 Gy (6.4 ± 4.3%) respectively. Plan metric prediction errors were -0.1 ± 1.5%, -0.5 ± 2.1%, -0.9 ± 2.2 Gy, and 0.1 ± 2.7 Gy for V95, V100, D95, and Dmean respectively. Plan metric prediction absolute errors were 1.1 ± 1.1%, 1.5 ± 1.5%, 1.9 ± 1.4 Gy, and 2.2 ± 1.6 Gy. Approximately 10% (25) of the plans studied were clearly identified by the prediction models as inferior quality plans needing further optimization and refinement.

CONCLUSION

Machine learning prediction models for treatment plan 3D dose distributions in online adaptive MRgRT were developed and tested. Clinical integration of the models requires minimal effort, producing 3D dose predictions for a new patient's plan using only target and OAR structures as inputs. These models can enable improved workflows for MRgRT through more informed plan optimization and plan quality assessment in real time.

Efficacy and safety of percutaneous computed tomography-guided high-dose-rate interstitial brachytherapy in treatment of oligometastatic lymph node metastases of retroperitoneal space

Purpose

To assess efficacy, safety, and outcome of computed tomography (CT)-guided high-dose-rate (HDR) interstitial brachytherapy in patients with oligometastatic lymph node metastases of the retroperitoneal space.

Material and methods

24 patients with a total of 47 retroperitoneal lymph node metastases from different primary tumors were treated with CT-guided interstitial brachytherapy using an ¹⁹²Ir source (single fraction irradiation). Every three months after treatment, clinical and imaging follow-up were conducted to evaluate local control and safety.

Results

Median follow-up was 9.6 months (range, 2.9-39.0 months). Local tumor control rate was 95.7%. The median diameter of the gross tumor volume was 2.2 cm (range, 1-8.6 cm), treated with a median D₁₀₀ (minimal enclosing tumor dose) of 14.9 Gy (range, 4.5-20.6 Gy). One severe adverse event (grade three) was recorded.

Cumulative median progression-free survival was 4.2 months (range, 1.4-23.7 months), and cumulative median overall survival after interstitial brachytherapy was 15.9 months (range, 3.8-39.0 months).

Conclusions

CT-guided HDR interstitial brachytherapy is a safe and feasible method for local ablation of oligometastatic lymph node metastases of the retroperitoneal space, and might provide a well-tolerated additional therapeutic option in the multidisciplinary management of selected patients.

Proton beam therapy in apneic oxygenation treatment of an unresectable hepatocellular carcinoma: A case report and review of literature

Presented here is the clinical course of a 63-year-old patient with a central, large and unresectable hepatocellular carcinoma (HCC) with liver metastases and tumor invasion of the portal and hepatic veins. After the tumor had been diagnosed, the patient was immediately treated with proton beam therapy (PBT), at a total dose of 60 Gy (relative biological effectiveness) in 20 fractions administered within 4 wk. To manage the respiratory movements, at the Rinecker Proton Therapy Center, apneic oxygenation was given daily, under general anesthesia. The patient tolerated both the PBT and general anesthesia very well, and did now show any signs of acute or late toxicity. The treatment was followed by constant reductions in the tumor marker alpha-fetoprotein and the cholestatic parameters gamma-glutamyltransferase and alkaline phosphatase. The patient commenced an adjuvant treatment with sorafenib, given at 6-wk intervals, after the PBT. Follow-up with regular magnetic resonance imaging has continued for 40 mo so far, demonstrating remarkable shrinkage of the HCC (maximal diameter dropping from approximately 13 cm to 2 cm). To date, the patient remains free of tumor recurrence. PBT served as a safe and effective treatment method for an unresectable HCC with vascular invasion.

A simulation study to assess the potential impact of developing normal tissue complication probability models with accumulated dose

PURPOSE

This study aimed to analyze the potential clinical impact of the differences between planned and accumulated doses on the development and use of normal tissue complication probability (NTCP) models.

METHODS AND MATERIALS

Thirty patients who were previously treated with stereotactic body radiation therapy for liver cancer and for whom the accumulated dose was computed were assessed retrospectively. The linear quadratic equivalent dose at 2 Gy per fraction and generalized equivalent uniform dose were calculated for planned and accumulated doses. Stomach and duodenal Lyman-Kutcher-Burman NTCP models (α/β = 2.5; n = .09) were developed on the basis of planned and accumulated generalized equivalent uniform doses and the differences between the models assessed. In addition, the error in determining the probability of toxicity on the basis of the planned dose was evaluated by comparing planned doses in the NTCP model that were created from accumulated doses.

RESULTS

The standard, planned-dose NTCP model overestimates toxicity risk for both the duodenal and stomach models at doses that are below approximately 20 Gy (6 fractions) and underestimates toxicity risk for doses above approximately 20 Gy (6 fractions). Building NTCP models with accumulated rather than planned doses changes the predicted risk by up to 16% (mean: 6%; standard deviation: 7%) for duodenal toxicity and 6% (mean: 2%; standard deviation: 2%) for stomach toxicity. For a protocol that plans a 10% iso-toxicity risk to the duodenum, a 15.7 Gy (6 fractions) maximum dose constraint would be necessary when using standard NTCP models on the basis of a planned dose and a 17.6 Gy (6 fractions) maximum dose would be allowed when using NTCP models on the basis of accumulated doses.

CONCLUSIONS

Assuming that accumulated dose is a more accurate representation of the true delivered dose than the planned dose, this simulation study indicates the need for prospective clinical trials to evaluate the impact of building NTCP models on the basis of accumulated doses.

Stereotactic body radiotherapy for centrally-located lung tumors with 56 Gy in seven fractions: A retrospective study

Stereotactic body radiotherapy (SBRT) for centrally-located lung tumors remains a challenge because of the increased risk of treatment-related adverse events (AEs), and uncertainty around prescribing the optimal dose. The present study reported the results of central tumor SBRT with 56 Gy in 7 fractions (fr) at the University of Tokyo Hospital. A total of 35 cases that underwent SBRT with or without volumetric-modulated arc therapy consisting of 56 Gy/7 fr for central lung lesions between 2010 and 2016 at the University of Tokyo Hospital were reveiwed. A central lesion was defined as a tumor within 2 cm of the proximal bronchial tree (RTOG 0236 definition) or within 2 cm in all directions of any critical mediastinal structure. Local control (LC), overall survival (OS), and AEs were investigated. The Kaplan-Meier method was used to estimate LC and OS. AEs were scored per the Common Terminology Criteria for Adverse Events Version 4.0. Thirty-five patients with 36 central lung lesions were included. Fifteen lesions were primary non-small cell lung cancer (NSCLC), 13 were recurrences of NSCLC, and 8 had oligo-recurrences from other primaries. Median tumor diameter was 29 mm. Eighteen patients had had prior surgery. At a median follow-up of 13.1 months for all patients and 18.3 months in surviving patients, 22 patients had died, ten due to primary disease (4 NSCLC), while three were treatment-related. The 1- and 2-year OS were 57.3 and 40.4%, respectively, and median OS was 15.7 months. Local recurrence occurred in only two lesions. 1- and 2-year LC rates were both 96%. Nine patients experienced grade ≥3 toxicity, representing 26% of the cohort. Two of these were grade 5, one pneumonitis and one hemoptysis. Considering the background of the subject, tumor control of our central SBRT is promising, especially in primary NSCLC. However, the safety of SBRT to central lung cancer remains controversial.

Dose to organ at risk and dose prescription in liver SBRT

Stereotactic body radiation therapy (SBRT) is delivered in a curative intent to many primary and secondary tumors. Concerning liver metastasis, SBRT can be safely delivered using one to five fractions. An excellent local control is obtained with doses from 20 to 60 Gy. For primary hepatic tumors, results are also good, but the risk of hepatic toxicity related to liver pre-existent pathology must be taken into account. Radiation induced liver disease (RILD) is not frequent in its classical presentation, but modifications of liver enzymes are often observed. Other toxicities of SBRT on the duodenum, small bowel and biliary tract are also described. With respect to contraindications and dose limitations on surrounding structures, SBRT is well tolerated and takes place among curative treatment of liver tumors, as surgery, radiofrequency and embolization.

VERO® radiotherapy for low burden cancer: 789 patients with 957 lesions

Purpose

The aim of this retrospective study is to evaluate patient profile, feasibility, and acute toxicity of RadioTherapy (RT) delivered by VERO® in the first 20 months of clinical activity.

Methods

Inclusion criteria: 1) adult patients; 2) limited volume cancer (M0 or oligometastatic); 3) small extracranial lesions; 4) treatment between April 2012 and December 2013 and 5) written informed consent. Two techniques were employed: intensity modulated radiotherapy (IMRT) and stereotactic body radiotherapy (SBRT). Toxicity was evaluated using Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG/EORTC) criteria.

Results

Between April 2012 and December 2013, 789 consecutive patients (957 lesions) were treated. In 84% of them one lesion was treated and in 16% more than one lesion were treated synchronously/metachronously; first radiotherapy course in 85%, re-irradiation in 13%, and boost in 2% of cases. The treated region included pelvis 46%, thorax 38%, upper abdomen 15%, and neck 1%. Radiotherapy schedules included <5 and >5 fractions in 75% and 25% respectively. All patients completed the planned treatment and an acceptable acute toxicity was observed.

Conclusions

RT delivered by VERO® was administrated predominantly to thoracic and pelvic lesions (lung and urologic tumours) using hypofractionation. It is a feasible approach for limited burden cancer offering short and well accepted treatment with favourable acute toxicity profile. Further investigation including dose escalation and other available VERO® functionalities such as real-time dynamic tumour tracking is warranted in order to fully evaluate this innovative radiotherapy system.

Avoiding Severe Toxicity From Combined BRAF Inhibitor and Radiation Treatment: Consensus Guidelines from the Eastern Cooperative Oncology Group (ECOG)

BRAF kinase gene V600 point mutations drive approximately 40% to 50% of all melanomas, and BRAF inhibitors (BRAFi) have been found to significantly improve survival outcomes. Although radiation therapy (RT) provides effective symptom palliation, there is a lack of toxicity and efficacy data when RT is combined with BRAFi, including vemurafenib and dabrafenib. This literature review provides a detailed analysis of potential increased dermatologic, pulmonary, neurologic, hepatic, esophageal, and bowel toxicity from the combination of BRAFi and RT for melanoma patients described in 27 publications. Despite 7 publications noting potential intracranial neurotoxicity, the rates of radionecrosis and hemorrhage from whole brain RT (WBRT), stereotactic radiosurgery (SRS), or both do not appear increased with concurrent or sequential administration of BRAFis. Almost all grade 3 dermatitis reactions occurred when RT and BRAFi were administered concurrently. Painful, disfiguring nondermatitis cutaneous reactions have been described from concurrent or sequential RT and BRAFi administration, which improved with topical steroids and time. Visceral toxicity has been reported with RT and BRAFi, with deaths possibly related to bowel perforation and liver hemorrhage. Increased severity of radiation pneumonitis with BRAFi is rare, but more concerning was a potentially related fatal pulmonary hemorrhage. Conversely, encouraging reports have described patients with leptomeningeal spread and unresectable lymphadenopathy rendered disease free from combined RT and BRAFi. Based on our review, the authors recommend holding BRAFi and/or MEK inhibitors ≥3 days before and after fractionated RT and ≥1 day before and after SRS. No fatal reactions have been described with a dose <4 Gy per fraction, and time off systemic treatment should be minimized. Future prospective data will serve to refine these recommendations.

Simple diagrammatic approach to delineate duodenum on a radiotherapy planning CT scan

In recent years, there has been increasing application of intensity-modulated radiotherapy and stereotactic body radiotherapy for the treatment of abdominal malignancies (stomach, pancreas, liver, spinal metastases). This warrants accurate delineation of organs at risk, especially the duodenum. The tortuous and curvy anatomy of duodenum often indistinguishable from adjoining organs is a practical challenge. Radiation Therapy Oncology Group (RTOG) has already published upper abdominal normal structure contouring guidelines to ease the delineation process. This pictorial essay following the RTOG guideline elaborates the step-by-step identification of the different parts of duodenum in relation to the adjoining important structures.

Extending the Frontiers Beyond Thermal Ablation by Radiofrequency Ablation: SBRT, Brachytherapy, SIRT (Radioembolization)

Metastatic spread of the primary is still defined as the systemic stage of disease in treatment guidelines for various solid tumors. This definition is the rationale for systemic therapy. Interestingly and despite the concept of systemic involvement, surgical resection as a local treatment has proven to yield long-term outcomes in a subset of patients with limited metastatic disease, supporting the concept of oligometastatic disease. Radiofrequency ablation has yielded favorable outcomes in patients with hepatocellular carcinoma and colorectal metastases, and some studies indicate its prognostic potential in combined treatments with systemic therapies. However, some significant technical limitations apply, such as size limitation, heat sink effects, and unpredictable heat distribution to adjacent risk structures. Interventional and non-invasive radiotherapeutic techniques may overcome these limitations, expanding the options for oligometastatic patients and cytoreductive concepts. Current data suggest very high local control rates even in large tumors at any given location in the human body. The article focusses on the characteristics and possibilities of stereotactic body radiation therapy, interstitial high-dose-rate brachytherapy, and Yttrium-90 radioembolization. In this article, we discuss the differences of the technical preferences as well as their impact on indications. Current data is presented and discussed with a focus on application in oligometastatic or cytoreductive concepts in different tumor biologies.