Space-making particle therapy for sarcomas derived from the abdominopelvic region

Spot scanning proton therapy for unresectable bulky retroperitoneal dedifferentiated liposarcoma: a case report

The development of effective treatment strategies for unresectable retroperitoneal sarcoma is desirable. Herein, we suggest that definitive proton therapy (PT) could be a promising treatment option, regardless of the large size of the tumor. A 52-year-old man presented with a discomfort of the lower abdomen. Computed tomography revealed a retroperitoneal tumor, measuring over 20 cm in the largest dimensions, which was surrounded by the gastrointestinal (GI) tract. Biopsy revealed dedifferentiated liposarcoma. Neoadjuvant chemotherapy was ineffective, and the tumor was ultimately deemed unresectable. The patient opted to receive PT instead of continuation of chemotherapy. Spot scanning PT (SSPT) at a total dose of 60.8 Gy (relative biological effectiveness) in 16 fractions was employed. SSPT administered a dose to the tumor while successfully sparing the surrounding GI tract. He did not receive any maintenance systemic therapy after PT. The tumor gradually shrunk over more than 7 years, with no evidence of recurrence outside the irradiation field. The initial measurable tumor volume of 2925 cc decreased to 214 cc at the final follow-up, seven and a half years after PT. The patient is alive without any severe complications.

Proton Beam Therapy for Hepatocellular Carcinoma: Multicenter Prospective Registry Study in Japan

PURPOSE

A prospective multicenter registry study was started May 2016 in Japan to evaluate the efficacy and safety of proton beam therapy (PBT) for hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Patients who received PBT for HCC from May 2016 to June 2018 were registered in the database of the Particle Beam Therapy Committee and Subcommittee of the Japanese Society for Radiation Oncology. Overall survival (OS), progression-free survival (PFS), and local recurrence were evaluated.

RESULTS

Of the 755 registered patients, 576 with initial PBT and no duplicate cancer were evaluated. At final follow-up, 322 patients were alive and 254 had died. The median follow-up period for survivors was 39 months (0-58 months). The median OS time of the 576 patients was 48.8 months (95% CI, 42.0-55.6 months) and the 1-, 2-, 3-, and 4-year OS rates were 83.8% (95% CI, 80.5%-86.6%), 68.5% (64.5%-72.2%), 58.2% (53.9%-62.2%), and 50.1% (44.9%-55.0%), respectively. Recurrence was observed in 332 patients, including local recurrence in 45 patients. The median PFS time was 14.7 months (95% CI, 12.4-17.0 months) and the 1-, 2-, 3-, and 4-year PFS rates were 55.2% (95% CI, 51.0%-59.2%), 37.5% (33.5%-41.5%), 30.2% (26.3%-34.2%), and 22.8% (18.5%-27.4%), respectively. The 1-, 2-, 3-, and 4-year OS rates were significantly higher for tumor size <5 versus 5 to 10 cm (P < .001) and <5 versus ≥10 cm (P < .001); Child-Pugh score A/B versus C (P < .001); and distance of the tumor from the gastrointestinal tract <1 versus 1 to 2 cm (P < .008) and <1 versus >2 cm (P < .001). At final follow-up, 27 patients (4.7%) had late adverse events of grade 3 or higher, with liver failure (n = 7), and dermatitis (n = 7) being most common.

CONCLUSIONS

This multicenter prospective data registry indicated that PBT for HCC gives good therapeutic effects (3-year local control rate of 90%) with a low risk of severe late adverse events.

Innovative Combination Treatment to Expand the Indications of Particle Therapy: Spacer Placement Surgery Using Bio-Absorbable Polyglycolic Acid Spacer

BACKGROUND

Particle therapy has favorable dose distribution and high curability. However, radiotherapy for malignant tumors adjacent to the gastrointestinal tract is contraindicated owing to its low tolerance. To overcome this, combination treatment with surgery to make a space between the tumor and adjacent gastrointestinal tract followed by particle therapy has been developed. Several materials have been used for the spacer and recently, we developed the absorbable polyglycolic acid (PGA) spacer, which has been used since 2019. This study is the first report of consecutive case series of spacer placement surgery using the PGA spacer.

STUDY DESIGN

Fifty consecutive patients undergoing spacer placement surgery with the PGA spacer were evaluated. Postoperative laboratory data, morbidity related to the treatment, and spacer volume after treatment were evaluated.

RESULTS

There were no treatment-related deaths, and all but 2 patients completed combination treatment. The median ratios of postoperative PGA spacer volume to the pretreatment volume were 96.9%, 87.7%, and 74.6% at weeks 2, 4, and 8, respectively. The spacer volume was maintained at 80% at 7 weeks and was predicted to be 50% at 15 weeks and 20% in 24 weeks.

CONCLUSIONS

Spacer placement surgery using the PGA spacer was feasible and tolerable. The PGA spacers maintained sufficient thickness during the duration of subsequent particle therapy. Combination treatment using the PGA spacer is innovative and has the potential to become a new standard curative local treatment.

Clinical impact of spacer placement surgery with expanded polytetrafluoroethylene sheet for particle therapy

BACKGROUND

Spacer placement surgery is useful in particle therapy (PT) for patients with abdominopelvic malignant tumors located adjacent to the gastrointestinal tract. This study aimed to assess the safety, efficacy, and long-term outcomes of spacer placement surgery using an expanded polytetrafluoroethylene (ePTFE) spacer.

METHODS

This study included 131 patients who underwent ePTFE spacer placement surgery and subsequent PT between September 2006 and June 2019. The overall survival (OS) and local control (LC) rates were calculated using Kaplan-Meier method. Spacer-related complications were classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0).

RESULTS

The median follow-up period after spacer placement surgery was 36.8 months. The 3-year estimated OS and LC rates were 60.5% and 76.5%, respectively. A total of 130 patients (99.2%) were able to complete PT. Spacer-related complications of ≥ grade 3 were observed in four patients (3.1%) in the acute phase and 13 patients (9.9%) in the late phase. Ten patients (7.6%) required removal of the ePTFE spacer.

CONCLUSIONS

Spacer placement surgery using an ePTFE spacer for abdominopelvic malignant tumors is technically feasible and acceptable for subsequent PT. However, severe spacer-related late complications were observed in some patients. Since long-term placement of a non-absorbable ePTFE spacer is associated with risks for morbidity and infection, careful long-term follow-up and prompt therapeutic intervention are essential when complications associated with the ePTFE spacer occur.

TRIAL REGISTRATION

retrospectively registered.

Three cases of retroperitoneal sarcoma in which bioabsorbable spacers (bioabsorbable polyglycolic acid spacers) were inserted prior to carbon ion radiotherapy

From August 2019 to August 2020, we inserted polyglycolic acid (PGA) spacers and administered carbon ion radiotherapy (CIRT) to three cases of retroperitoneal sarcoma at our hospital. We aimed to investigate its utility and safety for retroperitoneal sarcoma. We analyzed changes in PGA spacer volume and corresponding computed tomography (CT) values in addition to the dose distribution using in-room CT images that were obtained during treatment. We assessed adverse events and investigated the suitability, safety and effectivity of PGA spacer insertion. During treatment, changes in PGA spacer volumes and CT values were confirmed. Volumes increased in patients with a folded PGA spacer, and it increased 1.6-fold by the end of irradiation compared with planning CT. The CT values decreased by 20-50 Hounsfield units at the end of irradiation compared to the planning CT. Dose distribution evaluation showed that the dose to the gastrointestinal tract adjacent to the tumor was maintained below the tolerable dose, and a sufficient dose was delivered to the target by PGA spacer insertion. One case of subileus caused during abdominal surgery for PGA spacer insertion occurred. No other adverse events, such as digestive disorders, were observed. CIRT with PGA spacer insertion for retroperitoneal sarcomas is safe and effective. For cases in which there is no option but to perform irradiation using a PGA spacer, precautionary measures such as verification of dose distributions using CT images are necessary.

Prediction of the minimum spacer thickness required for definitive radiotherapy with carbon ions and photons for pelvic tumors: an in silico planning study using virtual spacers

We aimed to predict the minimum distance between a tumor and the gastrointestinal (GI) tract that can satisfy the dose constraint by creating simulation plans with carbon-ion (C-ion) radiotherapy (RT) and photon RT for each case assuming insertion of virtual spacers of various thicknesses. We enrolled 55 patients with a pelvic tumor adjacent to the GI tract. Virtual spacers were defined as the overlap volume between the GI tract and the volume expanded 7-17 mm from the gross tumor volume (GTV). Simulation plans (70 Gy in 35 fractions for at least 95% of the planning target volume [PTV]) were created with the lowest possible dose to the GI tract under conditions that meet the dose constraints of the PTV. We defined the minimum thickness of virtual spacers meeting D2 cc of the GI tract <50 Gy as 'MTS'. Multiple regression was used with explanatory variables to develop a model to predict MTS. We discovered that MTSs were at most 9 mm and 13 mm for C-ion RT and photon RT plans, respectively. The volume of overlap between the GI tract and a virtual spacer of 14 mm in thickness (OV14)-PTV was found to be the most important explanatory variable in the MTS prediction equation for both C-ion and photon RT plans. Multiple R2 values for the regression model were 0.571 and 0.347 for C-ion RT and photon RT plans, respectively. In conclusion, regression equations were developed to predict MTS in C-ion RT and photon RT.

Rectal dose-sparing effect with bioabsorbable spacer placement in carbon ion radiotherapy for sacral chordoma: dosimetric comparison of a simulation study

It is difficult to treat patients with an inoperable sarcoma adjacent to the gastrointestinal (GI) tract using carbon ion radiotherapy (C-ion RT), owing to the possible development of serious GI toxicities. In such cases, spacer placement may be useful in physically separating the tumor and the GI tract. We aimed to evaluate the usefulness of spacer placement by conducting a simulation study of dosimetric comparison in a patient with sacral chordoma adjacent to the rectum treated with C-ion RT. The sacral chordoma was located in the third to fourth sacral spinal segments, in extensive contact with and compressing the rectum. Conventional C-ion RT was not indicated because the rectal dose would exceed the tolerance dose. Because we chose spacer placement surgery to physically separate the tumor and the rectum before C-ion RT, bioabsorbable spacer sheets were inserted by open surgery. After spacer placement, 67.2 Gy [relative biological effectiveness (RBE)] of C-ion RT was administered. The thickness of the spacer was stable at 13-14 mm during C-ion RT. Comparing the dose-volume histogram (DVH) parameters, Dmax for the rectum was reduced from 67 Gy (RBE) in the no spacer plan (simulation plan) to 45 Gy (RBE) in the spacer placement plan (actual plan) when a prescribed dose was administered to the tumor. Spacer placement was advantageous for irradiating the tumor and the rectum, demonstrated using the DVH parameter analysis.

Impact of Carbon Ion Radiotherapy on Inoperable Bone Sarcoma

Simple Summary

The standard treatment for bone sarcoma is surgery with or without additional chemotherapy; however, complete resection of the tumor might not be possible in patients with locally advanced lesions. Management of patients with bone sarcoma who are unsuitable for surgery is challenging. Carbon ion radiotherapy (C-ion RT) was initiated in 1994 for treating various cancers in Japan and is being considered to be an effective treatment for unresectable bone sarcoma. However, there is a limited number of reports on the clinical outcomes of C-ion RT for bone sarcoma. Here, we aimed to analyze the clinical outcomes and prognostic factors among patients with unresectable bone sarcoma who were treated with C-ion RT. We found that C-ion RT had favorable overall survival and local control with low toxicity rates compared to surgery. Therefore, our results suggest a potential role for C-ion RT in the radical treatment of inoperable bone sarcoma.

Abstract

Management of patients with bone sarcoma who are unsuitable for surgery is challenging. We aimed to analyze the clinical outcomes among such patients who were treated with carbon ion radiotherapy (C-ion RT). We reviewed the medical records of the patients treated with C-ion RT between April 2011 and February 2019 and analyzed the data of 53 patients. Toxicities were classified using the National Cancer Institute’s Common Terminology Criteria for Adverse Events (Version 4.0). The median follow-up duration for all patients was 36.9 months. Histologically, 32 patients had chordoma, 9 had chondrosarcoma, 8 had osteosarcoma, 3 had undifferentiated pleomorphic sarcoma, and 1 had sclerosing epithelioid fibrosarcoma. The estimated 3-year overall survival (OS), local control (LC), and progression-free survival (PFS) rates were 79.7%, 88.6%, and 68.9%, respectively. No patients developed grade 3 or higher acute toxicities. Three patients developed both grade 3 radiation dermatitis and osteomyelitis, one developed both grade 3 radiation dermatitis and soft tissue infection, and one developed rectum-sacrum-cutaneous fistula. C-ion RT showed favorable clinical outcomes in terms of OS, LC, and PFS and low rates of toxicity in bone sarcoma patients. These results suggest a potential role for C-ion RT in the management of this population.