Stereotactic body radiotherapy (SBRT) is an effective radiation therapy technique that has allowed for shorter treatment courses, as compared to conventionally dosed radiation therapy. As its name implies, SBRT relies on daily image guidance to ensure that each fraction targets a tumor, instead of healthy tissue. Magnetic resonance imaging (MRI) offers improved soft-tissue visualization, allowing for better tumor and normal tissue delineation. MR-guided RT (MRgRT) has traditionally been defined by the use of offline MRI to aid in defining the RT volumes during the initial planning stages in order to ensure accurate tumor targeting while sparing critical normal tissues. However, the ViewRay MRIdian and Elekta Unity have improved upon and revolutionized the MRgRT by creating a combined MRI and linear accelerator (MRL), allowing MRgRT to incorporate online MRI in RT. MRL-based MR-guided SBRT (MRgSBRT) represents a novel solution to deliver higher doses to larger volumes of gross disease, regardless of the proximity of at-risk organs due to the (1) superior soft-tissue visualization for patient positioning, (2) real-time continuous intrafraction assessment of internal structures, and (3) daily online adaptive replanning. Stereotactic MR-guided adaptive radiation therapy (SMART) has enabled the safe delivery of ablative doses to tumors adjacent to radiosensitive tissues throughout the body. Although it is still a relatively new RT technique, SMART has demonstrated significant opportunities to improve disease control and reduce toxicity. In this review, we included the current clinical applications and the active prospective trials related to SMART. We highlighted the most impactful clinical studies at various tumor sites. In addition, we explored how MRL-based multiparametric MRI could potentially synergize with SMART to significantly change the current treatment paradigm and to improve personalized cancer care.

Introduction: High-dose total body irradiation (TBI) is often part of myeloablative conditioning in acute leukemia. Modern volumetric modulated arc therapy (VMAT)-based plans employ arcs to the inferior-most portion of the body that can be simulated in a head-first position and use 2D planning for the inferior body which can result in heterogeneous doses. Here, we describe our institution's unique protocol for delivering high-dose TBI entirely with VMAT and retrospectively compare dosimetric outcomes with helical tomotherapy (HT) plans. Additionally, we describe our method of oropharyngeal mucosal sparing that was implemented after fatal mucositis occurred in two patients. Methods: Thirty-one patients were simulated and treated in head-first (HFS) and feet-first (FFS) orientations. Patients were treated with VMAT (n = 26) or HT (n = 5). In VMAT plans, to synchronize doses between the orientations, images were deformably registered and the HFS dose was transferred to the FFS plan and used as a background dose when optimizing plans. Six to eight isocenters with two arcs per isocenter were generated. HT was delivered with an established technique. Patients were treated to 13.2 Gy over eight twice daily fractions. Dosimetric outcomes and toxicities were retrospectively compared. Results: Prescription dose and organ at risk (OAR) constraints were met for all patients. Lower lung doses were achieved with VMAT relative to HT plans (7.4 vs 7.7 Gy, P = .009). Statistically significant improvement in mucositis was not achieved after adopting a mucosal-sparing technique, however lower doses to the oropharyngeal mucosal were achieved (6.9 vs 14.1 Gy, P = .009), and no further mucositis-related deaths occurred. Conclusions: This full-body VMAT method of TBI achieves dose goals, eliminates risk of heterogenous doses within the femur, and demonstrates that selective OAR sparing with the purpose of reducing TBI-related morbidity and mortality is possible at any institution with a VMAT-capable linear accelerator.

Purpose of review: Thirty-day mortality (30DM) is an emerging consideration for determining whether terminally ill adult patients may benefit from palliative radiotherapy (RT). However, the efficacy and ethics of delivering palliative RT at the end of life (EOL) in children are seldom discussed and not well-established. Recent findings: Palliative RT is perhaps underutilized among patients ≤21 years old with rates as low as 11%. While effective when delivered early, clinical benefit decreases when administered within the last 30 days of life. Pediatric 30DM rates vary widely between institutions (0.7–30%), highlighting the need for standardized practices. Accurate prognosis estimation remains challenging and prognostic models specific to palliative pediatric patients are limited. Discordance between provider and patient/parent perceptions of prognosis further complicates decision-making. Summary: RT offers effective symptom control in pediatric patients when administered early. However, delivering RT within the last 30 days of life may provide limited clinical benefit and hinder optimal EOL planning and care. Early referral for palliative RT, preferably with fewer fractions (five or fewer), along with multidisciplinary supportive care, optimizes the likelihood of maintaining patients’ quality of life. Prognosis estimation remains difficult, and improving patient and family understanding is crucial. Further research is needed to refine prognostic models and enhance patient-centered care.

The delivery of post-operative radiotherapy (PORT) for solid tumor bone metastases is a well-established practice that aims to enhance patient outcomes following surgical intervention. Surgery for osseous metastases serves to stabilize bone, alleviate pain, reduce tumor volume, and relieve pressure on critical neurological components. Radiotherapy complements surgery by addressing residual malignant disease and cancer-induced pain. Together, they serve to improve local control, maximize functional outcomes, control pain, and improve patients’ overall quality of life. Despite the prevalence of non-spine bone metastases (NSBMs) necessitating operative intervention, structured guidelines for palliative PORT are limited. This is, in part, due to a paucity of research specific to this topic. As such, a wide array of doses are deemed acceptable, leading to varied practice patterns. Conversely, there is more extensive literature available, including prospective trials, for the management of post-operative spine bone metastases (SBMs). This includes advances such as stereotactic body radiotherapy (SBRT), separation surgery, and the utilization of simultaneous integrated boosts that enable evidence driven, safe dose escalation. This mini-review aims to provide a summary of the existing literature on palliative postoperative radiotherapy for both NSBMs and SBMs. By offering historical context and summarizing current evidence, this article seeks to aid clinical decision-making and highlight areas for future research to enhance treatment standardization and patient care.

With improving rates of survival among patients with metastatic malignancies, the request for palliative re-irradiation and re-re-irradiation continues to grow despite an absence of standardized guidelines. With only limited data regarding extra-cranial third-course palliative radiation, many radiation oncologists may feel uncomfortable proceeding with third-course irradiation of the same site. The review explores the available modern data regarding re-re-irradiation. A literature review identified four modern peer-reviewed studies investigating palliative, extra-cranial third-course irradiation with external beam radiation. These studies were retrospective, small, and heterogenous. While they reported comparable rates of pain palliation to first course irradiation and low rates of acute toxicity, interpretation is complicated by heterogeneous treatment parameters and insufficient reporting of cumulative dose equivalents and time intervals. With limited data available, it is critical to prioritize patient safety and quality of life in palliative radiotherapy. Patient selection should be meticulous, considering factors such as initial treatment response and predicted life expectancy. Conformal radiation techniques, strict immobilization, and daily image guidance should be employed to minimize toxicity to organs at risk (OARs). Long-term follow-up is essential for identifying and managing late toxicities effectively. Despite the scarcity of data, retrospective series suggest that extra-cranial third course irradiation can provide effective pain palliation comparable to first-course irradiation with tolerable rates of toxicity. However, careful consideration of patient prognosis and adherence to established principles of palliative radiotherapy are essential in decision-making. Further research and long-term follow-up are needed to refine treatment strategies and ensure safe and efficacious care delivery in this complex clinical scenario.

Portal vein stenosis (PVS) is a rare but potentially devastating complication arising after definitive treatment of pancreatic cancer. The condition can manifest as symptomatic ascites, abdominal pain, splenomegaly, thrombocytopenia, as well as hemorrhage secondary to gastric or esophageal varices. The etiology is often multifactorial but has been associated with tumor progression, chemotherapy, vascular surgery, and radiation. We present a case in which a man with borderline-resectable pancreatic cancer developed symptomatic ascites secondary to PVS following treatment with neoadjuvant chemotherapy and subsequent 5-fraction MRI-guided adaptive radiation therapy and pancreaticoduodenectomy with vascular reconstruction. Though the incidence of PVS after ablative radiation therapy and surgery for pancreatic cancer appears to be low, it may be under-reported, and patients should be closely monitored in the setting of re-irradiation or planned vascular reconstruction. These findings may help inform future radiation therapy treatment planning guidelines to avoid excessive dose to the portal vein.