Objective: Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. We present our preliminary results on the clinical utilization of MRI-guided adaptive radiotherapy (MRgRT) for prostate cancer patients with the workflow, dosimetric parameters, toxicities and prostate-specific antigen (PSA) response. Methods: 50 prostate cancer patients treated with ultra-hypofractionation were included in the study. Treatment was performed with intensity-modulated radiation therapy (step and shoot) technique and daily plan adaptation using MRgRT. The SBRT consisted of 36.25 Gy in 5 fractions with a 7.25 Gy fraction size. The time for workflow steps was documented. Patients were followed for the acute and late toxicities and PSA response. Results: The median follow-up for our cohort was 10 months (range between 3 and 29 months). The median age was 73.5 years (range between 50 and 84 years). MRgRT was well tolerated by all patients. Acute genitourinary (GU) toxicity rate of Grade 1 and Grade 2 was 28 and 36%, respectively. Only 6% of patients had acute Grade 1 gastrointestinal (GI) toxicity and there was no Grade ≥ 2 GI toxicity. To date, late Grade 1 GU toxicity was experienced by 24% of patients, 2% of patients experienced Grade 2 GU toxicity and 6% of patients reported Grade 2 GI toxicity. Due to the short follow-up, PSA nadir has not been reached yet in our cohort. Conclusion: In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation has an acceptable acute and very low late toxicity profile. Advances in knowledge: MRgRT represents a new markerless method for delivering SBRT for localized prostate cancer providing online adaptive planning and real-time tracking and acute and late toxicity profile is acceptable.

This study evaluates treatment outcomes and possible prognostic factors of inoperable cervical cancer patients treated with external beam radiotherapy (EBRT) and high–dose rate brachytherapy (HDR BRT). Between 1993 and 2000, 183 patients with cervical cancer were treated at our institute. Radiotherapy was the sole treatment modality until January 1997; after the announcement of National Cancer Institute in 1999, 40 mg/m² of cisplatin (49%) was routinely applied every week. Median age was 54 years (32–92 years). Most patients (88%) had advanced-stage disease (IIB–IIIB). With a median follow-up time of 45 months (6–121 months), the 5-year overall survival (OS), local recurrence–free survival, disease-free survival (DFS), and distant metastasis–free survival (DMFS) rates were 55%, 71%, 51%, and 77%, respectively. Univariate analysis revealed that age, tumor size, lymph node status, and concomitant cisplatin were prognostic factors for OS. The DFS rates were lower in young age group. Patients with tumor greater than 4 cm and age greater than 40 were at greater risk for local recurrence. Distant metastases were more frequent in patients with adenocarcinoma. Concurrent cisplatin use increases DMFS rates (91% vs 78%; P= 0.05). In multivariate analysis, extensive stage, parametrial infiltration, young age, adenocarcinoma histopathology, and lymph node metastasis were negative prognostic factors for OS while concomitant cisplatin increases OS. Likewise, patients with extensive stage, adenocarcinoma, and without concurrent cisplatin administration had more risk for distant metastasis. There was no treatment-related mortality. Grade 3–4 morbidity rates were seen only in eight patients (4%). The combination of EBRT and HDR BRT together with concomitant chemotherapy in the treatment of locally advanced carcinoma of cervix is safe and well tolerated with acceptable morbidity.

Lattice Radiotherapy (LRT) is a technique in which heterogeneous doses are delivered to the target so large tumors can have optimal doses of radiation without compromising healthy tissue sparing. To date, case reports and case series documented its application for bulky tumors mainly in the pelvic region. LRT not only provides dosimetric advantages but also promotes tumor control by triggering some radiobiological and immunological pathways. We report two cases of giant liver metastases for whom other treatment options were not suitable. We treated both patients with Magnetic Resonance Image-Guided Radiotherapy (MRgRT) with online adaptive LRT (OALRT) technique. Adaptive plans were generated before each fraction. Tumors were observed to have regressed interfractionally so the location and number of spheres were adapted to tumor size and daily anatomy of the surrounding organs at risk (OAR). Both patients had good treatment compliance without any Grade 3+ side effects. They are both under follow-up and report improvement. By reporting the first application of OALRT by using MRgRT in liver metastases, we show that MRgRT is a promising modality for LRT technique with better target and OAR visualization as well as online adaptive planning before each fraction according to the daily anatomy of the patient.

Background: Magnetic resonance-guided radiotherapy (MRgRT) utilization is rapidly expanding, driven by advanced capabilities including better soft tissue imaging, continuous intrafraction target visualization, automatic triggered beam delivery, and the availability of on-table adaptive replanning. Our objective was to describe patterns of 0.35 Tesla (T)-MRgRT utilization in Europe and Asia among early adopters of this novel technology. Methods: Anonymized administrative data from all 0.35T-MRgRT treatment systems in Europe and Asia were extracted for patients who completed treatment from 2015 to 2020. Detailed treatment information was analyzed for all MR-linear accelerators (linac) and -cobalt systems. Results: From 2015 through the end of 2020, there were 5796 completed treatment courses delivered in 46,389 individual fractions. 23.5% of fractions were adapted. Ultra-hypofractionated (UHfx) dose schedules (1–5 fractions) were delivered for 63.5% of courses, with 57.8% of UHfx fractions adapted on-table. The most commonly treated tumor types were prostate (23.5%), liver (14.5%), lung (12.3%), pancreas (11.2%), and breast (8.0%), with increasing compound annual growth rates (CAGRs) in numbers of courses from 2015 through 2020 (pancreas: 157.1%; prostate: 120.9%; lung: 136.0%; liver: 134.2%). Conclusions: This is the first comprehensive study reporting patterns of utilization among early adopters of a 0.35T-MRgRT system in Europe and Asia. Intrafraction MR image-guidance, advanced motion management, and increasing adoption of on-table adaptive RT have accelerated a transition to UHfx regimens. MRgRT has been predominantly used to treat tumors in the upper abdomen, pelvis and lungs, and increasingly with adaptive replanning, which is a radical departure from legacy radiotherapy practices.