MRI-guided radiotherapy for PVTT in HCC patients: evaluation of the efficacy and safety

Impact of intrafraction motion in pancreatic cancer treatments with MR-guided adaptive radiation therapy

Purpose

The total time of radiation treatment delivery for pancreatic cancer patients with daily online adaptive radiation therapy (ART) on an MR-Linac can range from 50 to 90 min. During this period, the target and normal tissues undergo changes due to respiration and physiologic organ motion. We evaluated the dosimetric impact of the intrafraction physiological organ changes.

Methods

Ten locally advanced pancreatic cancer patients were treated with 50 Gy in five fractions with intensity-modulated respiratory-gated radiation therapy on a 0.35-T MR-Linac. Patients received both pre- and post-treatment volumetric MRIs for each fraction. Gastrointestinal organs at risk (GI-OARs) were delineated on the pre-treatment MRI during the online ART process and retrospectively on the post-treatment MRI. The treated dose distribution for each adaptive plan was assessed on the post-treatment anatomy. Prescribed dose volume histogram metrics for the scheduled plan on the pre-treatment anatomy, the adapted plan on the pre-treatment anatomy, and the adapted plan on post-treatment anatomy were compared to the OAR-defined criteria for adaptation: the volume of the GI-OAR receiving greater than 33 Gy (V33Gy) should be ≤1 cubic centimeter.

Results

Across the 50 adapted plans for the 10 patients studied, 70% were adapted to meet the duodenum constraint, 74% for the stomach, 12% for the colon, and 48% for the small bowel. Owing to intrafraction organ motion, at the time of post-treatment imaging, the adaptive criteria were exceeded for the duodenum in 62% of fractions, the stomach in 36%, the colon in 10%, and the small bowel in 48%. Compared to the scheduled plan, the post-treatment plans showed a decrease in the V33Gy, demonstrating the benefit of plan adaptation for 66% of the fractions for the duodenum, 95% for the stomach, 100% for the colon, and 79% for the small bowel.

Conclusion

Post-treatment images demonstrated that over the course of the adaptive plan generation and delivery, the GI-OARs moved from their isotoxic low-dose region and nearer to the dose-escalated high-dose region, exceeding dose-volume constraints. Intrafraction motion can have a significant dosimetric impact; therefore, measures to mitigate this motion are needed. Despite consistent intrafraction motion, plan adaptation still provides a dosimetric benefit.

Combination treatment of transcatheter arterial chemoembolization, intensity-modulated radiotherapy, and sorafenib for hepatocellular carcinoma with macrovascular invasion

This study evaluated the therapeutic effects and toxic reactions of combining transcatheter arterial chemoembolization (TACE) and intensity-modulated radiotherapy (IMRT) with sorafenib for the treatment of advanced hepatocellular carcinoma (HCC) patients with macrovascular invasion (MVI). We retrospectively analyzed the clinical data of 82 HCC patients with MVI, among whom 35 were treated with TACE plus IMRT alone, and 47 were treated with the combined therapy of TACE, IMRT, and sorafenib. The progression-free survival (PFS), overall survival (OS), and adverse events were assessed. The baseline characteristics were comparable between the 2 groups (all P > .05). In the TACE plus IMRT plus sorafenib group, the median PFS was 17.2 months (95% confidence interval, 14.1-19.9), significantly longer than the 9.4 months (95% confidence interval, 6.8-11.2) observed in the TACE plus IMRT group (P < .001). Additionally, patients treated with the TACE plus IMRT plus sorafenib showed a longer median OS than those treated with TACE plus IMRT alone (24.1 vs 17.3 months; P < .001). The occurrence rates of grade 1 to 2 hand-foot syndrome, other skin reactions, diarrhea, and hair loss were higher in the TACE plus IMRT plus sorafenib group (all P < .05). There were no grade 4 or higher adverse events in either group. The combination of TACE plus IMRT with sorafenib provided substantial clinical benefits in the treatment of HCC patients with MVI, increasing the tumor response rate and prolonging both PFS and OS. This approach demonstrated a tolerable and manageable safety profile.

Local Therapies for Hepatocellular Carcinoma and Role of MRI-Guided Adaptive Radiation Therapy

Hepatocellular carcinoma (HCC) is the most common liver tumor, with a continually rising incidence. The curative treatment for HCC is surgical resection or liver transplantation; however, only a small portion of patients are eligible due to local tumor burden or underlying liver dysfunction. Most HCC patients receive nonsurgical liver-directed therapies (LDTs), including thermal ablation, transarterial chemoembolization (TACE), transarterial radioembolization (TARE), and external beam radiation therapy (EBRT). Stereotactic ablative body radiation (SABR) is a specific type of EBRT that can precisely deliver a high dose of radiation to ablate tumor cells using a small number of treatments (or fractions, typically 5 or less). With onboard MRI imaging, MRI-guided SABR can improve therapeutic dose while minimizing normal tissue exposure. In the current review, we discuss different LDTs and compare them with EBRT, specifically SABR. The emerging MRI-guided adaptive radiation therapy has been reviewed, highlighting its advantages and potential role in HCC management.

SPIO-enhanced 0.35T MRI-guided radiotherapy for liver malignancies: usefulness in tumor visualization

OBJECTIVES

The purpose of this study was to investigate the changes of tumor-to-liver signal ratio in a 0.35T MRI-guided radiotherapy system and to evaluate the usefulness and pitfalls of superparamagnetic iron oxide (SPIO) administration for visualization of liver tumors.

METHODS

Forty-two patients treated with MRI-guided stereotactic ablative radiotherapy (SABR) for liver tumors were included in this study. The tumor-to-liver signal ratios before and after SPIO administration were retrospectively assessed and compared on true fast imaging with steady-state precession (FISP).

RESULTS

Before SPIO administration, liver tumors were either invisible or barely visible in 15 cases (36%), but all tumors became visible after SPIO administration. The mean values of tumor-to-liver signal ratio before and after SPIO administration were 0.939 ± 0.201 and 1.336 ± 0.300, respectively (mean ± standard deviation, p < 0.001). In six (14%) patients, liver tumors were visible on true FISP imaging before SPIO administration, but became invisible after administration.

CONCLUSIONS

This study showed that liver tumors that are invisible on true FISP imaging can be made visible by administration of SPIO, and that MRI-guided SABR can be performed accurately.

ADVANCES IN KNOWLEDGE

This is the first report to examine the usefulness of liver-specific contrast agent superparamagnetic iron oxides in 0.35T MRI-guided radiation therapy. Liver tumors that are invisible on true fast imaging with steady-state precession can be made visible by administration of superparamagnetic iron oxides.

Hypofractionated Radiotherapy for Palliation of Main Portal Vein Tumor Thrombosis

Background

Hypofractionated radiotherapy delivered for portal vein tumor thrombosis (PVTT) located in the main portal vein is rarely exploited. The study aimed to evaluate the efficacy and safety of hypofractionated radiotherapy as palliative treatment for PVTT in cirrhotic patients with hepatocellular carcinoma.

Methods

From March 2016 to July 2020, 16 patients (mean age, 59.1 ± 6.3 years; 15 men) with hepatocellular carcinoma and hepatitis virus-related cirrhosis who underwent hypofractionated radiotherapy for PVTT (located in the main portal vein) in our institute were retrospectively reviewed.

Results

Complete response of the PVTT was observed in 4 cases (25%) with partial response in 7 cases (43.75%) and stable disease in 5 cases (31.25%). Symptom relief was observed in all 7 patients suffering from ventosity. The median time to progression was 6 months (interquartile range, IQR: 6–12 months). Eight patients (50%) failed due to primary cancer progression, 7 patients failed due to extrahepatic metastasis, and only 1 patient failed due to PVTT progression. The median overall survival was 17.4 months (IQR: 8–25 months). Grade I/II anorexia/nausea was observed in 14 patients (87.5%) and Grade I/II leukopenia was observed in 14 patients (87.5%). No complications ≥ Grade III were observed.

Conclusions

Hypofractionated radiotherapy as palliative treatment appears effective and safe for PVTT located in the main portal vein in cirrhotic patients with advanced hepatocellular carcinoma, yielding a high rate of tumor response. Further study is warranted.

Magnetic Resonance Image-Guided Hypofractionated Ablative Radiation Therapy for Hepatocellular Carcinoma With Tumor Thrombus Extending to the Right Atrium

Hepatocellular carcinoma (HCC) presenting with tumor thrombus (TT) and inferior vena cava (IVC)/right atrium (RA) infringement point to an advanced-stage disease that is deemed inoperable. Stereotactic body radiotherapy is an emerging treatment option for this group of patients with promising outcomes in recent studies that are comparable to conventional treatment methods, namely, transarterial chemoembolization and transarterial radioembolization. Here, we report a case of HCC with RA extension through the IVC. The patient was referred to our clinic for treatment options, and he was found suitable for magnetic resonance imaging-guided radiotherapy (MRgRT). We treated the patient with MRgRT in five fractions to a total dose of 40 Gray. The tumor was tracked during the treatment sessions, and adaptive treatment planning was performed before each fraction. The patient tolerated the treatment well with no acute grade 3-4 toxicities. The last follow-up showed that the patient had a complete biochemical response and is now a candidate for an orthotopic liver transplant. To our knowledge, this report is the first to document the MRgRT treatment of an HCC with TT and RA extension. MRgRT is safe and feasible for this patient group and can be an effective bridging therapy for liver transplants.