The role of carbon ion radiotherapy for unresectable locally recurrent rectal cancer: a single institutional experience

Carbon Ion Radiotherapy Reirradiation for Recurrent Malignancy: A Systematic Assessment

Reirradiation presents a significant challenge despite recent advances in modern radiation therapy. Carbon ion radiotherapy has garnered increasing attention among radiation oncologists due to its potentially superior physical dosimetric distribution and radiobiological advantages. This systematic review comprehensively evaluated clinical outcomes from 27 original studies on the use of carbon ion reirradiation for locoregional recurrent malignancies, including those affecting the central nervous system, lung, head and neck, pancreas, liver, rectum, and gynecological sites. The findings suggest that carbon ion reirradiation for locoregional recurrent malignancies yields favorable clinical outcomes with a relatively low incidence of high-grade toxicities. For recurrent nasopharyngeal carcinoma, the reported 2-year overall survival, local control, regional control, and metastasis-free survival rates were 83.7%, 58.0%, 87.3%, and 94.7%, respectively. Grade ≥3 late nasopharyngeal necrosis occurred in 16% (33/206) of cases. In the case of recurrent glioblastoma, median overall survival and local control survival were reported at 13 and 7 months, respectively, with minimal high-grade complications; observed low-grade toxicities included acute involuntary movements, incomplete hemiparesis, and late-onset dysphasia. For recurrent lung cancer, 2-year local control and overall survival rates were reported as 54.0% and 61.9%, respectively. Grade ≥3 toxicities included two cases of radiation pneumonitis and one case of bronchopleural fistula. In recurrent pancreatic cancer, 1-year local control, progression-free survival, and overall survival rates were 53.5%, 24.5%, and 48.7%, respectively. A high-grade complication of Grade 3 acute duodenal stenosis was observed in one patient. Additionally, concurrent chemotherapy with carbon ion reirradiation was associated with minimal high-grade additive toxicities. Overall, carbon ion reirradiation appears to be a potentially safe and effective reirradiation modality for treating locoregional recurrent malignancies, though data remains limited.

Carbon-Ion Radiation Therapy for Unresectable Locally Recurrent Colorectal Cancer: A Promising Curative Treatment for Both Radiation Therapy: Naïve Cases and Reirradiation Cases

PURPOSE

It is difficult to effectively cure patients with unresectable locally recurrent colorectal cancers (LRCRCs) using conventional chemotherapy or chemoradiation therapy. Furthermore, treatment options vary depending on the patient's history of radiation therapy. Carbon-ion radiation therapy (CIRT) is a potentially curative treatment for these patients. Here, we compare the treatment outcomes of radiation therapy-naïve cases (nRT) and re-irradiation cases (reRT).

METHODS AND MATERIALS

Patients with LRCRC treated with CIRT at QST Hospital between 2003 and 2019 were eligible. CIRT was administered daily 4 d/wk for 16 fractions. The total irradiated dose was set at 73.6 Gy (relative biologic effectiveness-weighted dose [RBE]) for nRT and 70.4 Gy (RBE) for reRT patients.

RESULTS

We included 390 nRT cases and 83 reRT cases. The median follow-up period from the initiation of CIRT was 48 (5-208) months. The 3-year overall survival (OS) rates for nRT and reRT were 73% (95% CI, 68%-77%) and 76% (65%-84%), respectively. The 5-year OS rates were 50% (45%-55%) and 50% (38%-61%), respectively. These rates did not differ significantly (P = .55). The 3-year local control (LC) rates for nRT (73.6 Gy) and reRT (70.4 Gy) cases were 80% (75%-84%) and 80% (68%-88%), respectively. The 5-year LC rates were 72% (67%-78%) and 69% (55%-81%), respectively, without a significant difference (P = .56).

CONCLUSIONS

Our results suggest that CIRT for LRCRC is a very effective and promising treatment for both nRT and reRT cases.

Clinical indications for carbon-ion radiotherapy in the UK: A critical review

INTRODUCTION

Carbon-ion radiotherapy (CIRT) has unique radiobiological properties that cause increased radiobiological effect and tumour control, especially with hypoxic tissues. This critical review aimed to evaluate clinical response to CIRT across all published tumour sites to establish if there is a clinical need for a CIRT centre in the UK.

METHODS

A critical review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Literature searching was undertaken in November 2022 within the PubMed, Science Direct, SCOPUS and Web of Science databases using the term 'carbon ion radiotherapy' in the title, abstract or author keywords.

RESULTS

After critical appraisal, data was extracted from 78 primary study papers. Strong evidence supported use of CIRT for chondrosarcoma, chordoma, nasopharyngeal, non-small cell lung cancer (NSCLC), oral cavity, prostate, rectal and salivary gland tumours. Further research is needed to strengthen the evidence base for some other tumour types.

CONCLUSION

The UK's incidence and mortality rates suggest a clinical need for CIRT for chondrosarcoma, chordoma, NSCLC, oral cavity, prostate, and rectal tumours. There is a need to improve survivorship amongst pancreatic, liver, and oesophageal cancer patients. Data published relating to CIRT for these tumours is promising but of lower quality and more research is needed in these areas.

IMPLICATIONS FOR PRACTICE

The clinical response to CIRT for certain tumours suggests the need for a carbon-ion centre in the UK. Demand for further research [phase III trials] has been identified, giving the UK opportunity to establish a research centre, with opportunity to treat, contributing to world-renowned research whilst improving patient outcomes.

Definitive carbon ion re-irradiation with pencil beam scanning in the treatment of unresectable locally recurrent rectal cancer

This study aimed to evaluate the oncological outcomes and safety of carbon ion re-irradiation with pencil beam scanning (PBS) delivery technique for previously irradiated and unresectable locally recurrent rectal cancer (LRRC). Between June 2017 and September 2021, 24 patients of unresectable LRRC with prior pelvic photon radiotherapy who underwent carbon ion re-irradiation at our institute were retrospectively analyzed. Carbon ion radiotherapy was delivered by raster scanning with a median relative biological effectiveness-weighted dose of 72 Gy in 20 fractions. Weekly CT reviews were carried out, and offline adaptive replanning was performed whenever required. The median follow-up duration was 23.8 months (range, 6.2-47.1 months). At the last follow-up, two patients had a local disease progression, and 11 patients developed distant metastases. The 1- and 2-year local control, progression-free survival and overall survival rates were 100 and 93.3%, 70.8 and 45.0% and 86.7 and 81.3%, respectively. There were no Grade 3 or higher acute toxicities observed. Three patients developed Grade 3 late toxicities, one each with gastrointestinal toxicity, skin reaction and pelvic infection. In conclusion, definitive carbon ion re-irradiation with PBS provided superior oncologic results with tolerable toxicities and may be served as a curative treatment strategy in unresectable LRRC.

Particle beam therapy for pelvic recurrence of colorectal cancer: a registry data analysis in Japan and a systematic review

The aim of this study was to investigate the efficacy and safety of particle beam therapy (PBT) with proton or carbon ion beam for pelvic recurrence of colorectal cancer (PRCC) by comparing the clinical outcomes of a dataset of prospectively enrolled patients for PBT with those from the literature, which were collected by a systematic review of external X-ray radiotherapy (XRT) and PBT. Patients with PRCC treated at 14 domestic facilities between May 2016 and June 2019 and entered the database for prospective observational follow-up were analyzed. The registry data analyzed included 159 PRCC patients treated with PBT of whom 126 (79%) were treated with carbon ion radiation therapy (CIRT). The 3-year overall survival and local control rate were 81.8 and 76.4%, respectively. Among these PRCC patients, 5.7% had Grade 3 or higher toxicity. Systematic search of PubMed and Cochrane databases published from January 2000 to September 2020 resulted in 409 abstracts for the primary selection. Twelve studies fulfilled the inclusion criteria. With one additional publication, 13 studies were selected for qualitative analysis, including 9 on XRT and 4 on PBT. There were nine XRT studies, which included six on 3D conformal radiotherapy and three on stereotactic body radiation therapy, and four PBT studies included three on CIRT and one on proton therapy. A pilot meta-analysis using literatures with median survival time extractable over a 20-month observation period suggested that PBT, especially CIRT, may be a promising treatment option for PRCC not amenable to curative resection.

Calibration and evaluation of the relative biological effectiveness for carbon-ion radiotherapy in a new relative to a clinically applied treatment planning system

BACKGROUND

The study objective was to validate the relative biological effectiveness (RBE) in RayStation for carbon-ion radiotherapy (CIRT) using the Syngo treatment planning system as reference.

METHODS

Local effect model I was established in RayStation (Ray-LEM) with the same parameters as in LEM I in Syngo (Syngo-LEM). Three cube plans covering most of the tumors treated at our center were generated with Syngo-LEM. Ray-LEM re-calculated the Syngo plans and compared the RBEs to the Syngo counterparts. The results showed that RayStation RBE was smaller than Syngo RBE. To ensure that Ray-LEM reproduced Syngo RBE, the observed deviations were used to scale the maximum RBE (RBEmax) in Ray-LEM. After this calibration, we further compared the RayStation RBE to Syngo RBE using additional plans in both homogeneous phantoms and patients, to ensure that the calibrated Ray-LEM reproduced Syngo RBE even with more complex planning features.

RESULTS

The calibration increased the RBEmax by 2.3% to raise the Ray-LEM RBE. The target mean RBE deviations in the phantom evaluation plans were median: 0.0 (minimum: - 1.1 to maximum: 0.7) %, and the target mean RBE deviations of the clinical target volumes of 16 patient cases were - 0.4 (- 1.5 to 0.2) %.

CONCLUSIONS

The residual RBE difference between RayStation and Syngo was found to be ≤ 1.0%. Thus, we can propose to use RayStation for clinical CIRT treatment planning. However, the potential differences due to the absorbed beam model warrants further exploration.

Flourish of Proton and Carbon Ion Radiotherapy in China

Proton and heavy ion therapy offer superior relative biological effectiveness (RBE) in the treatment of deep-seated tumors compared with conventional photon radiotherapy due to its Bragg-peak feature of energy deposition in organs. Many proton and carbon ion therapy centers are active all over the world. At present, five particle radiotherapy institutes have been built and are receiving patient in China, mainly including Wanjie Proton Therapy Center (WPTC), Shanghai Proton Heavy Ion Center (SPHIC), Heavy Ion Cancer Treatment Center (HIMM), Chang Gung Memorial Hospital (CGMH), and Ruijin Hospital affiliated with Jiao Tong University. Many cancer patients have benefited from ion therapy, showing unique advantages over surgery and chemotherapy. By the end of 2020, nearly 8,000 patients had been treated with proton, carbon ion or carbon ion combined with proton therapy. So far, there is no systemic review for proton and carbon ion therapy facility and clinical outcome in China. We reviewed the development of proton and heavy ion therapy, as well as providing the representative clinical data and future directions for particle therapy in China. It has important guiding significance for the design and construction of new particle therapy center and patients’ choice of treatment equipment.

Physics and biomedical challenges of cancer therapy with accelerated heavy ions

Radiotherapy should have low toxicity in the entrance channel (normal tissue) and be very effective in cell killing in the target region (tumour). In this regard, ions heavier than protons have both physical and radiobiological advantages over conventional X-rays. Carbon ions represent an excellent combination of physical and biological advantages. There are a dozen carbon-ion clinical centres in Europe and Asia, and more under construction or at the planning stage, including the first in the USA. Clinical results from Japan and Germany are promising, but a heated debate on the cost-effectiveness is ongoing in the clinical community, owing to the larger footprint and greater expense of heavy ion facilities compared with proton therapy centres. We review here the physical basis and the clinical data with carbon ions and the use of different ions, such as helium and oxygen. Research towards smaller and cheaper machines with more effective beam delivery is necessary to make particle therapy affordable. The potential of heavy ions has not been fully exploited in clinics and, rather than there being a single 'silver bullet', different particles and their combination can provide a breakthrough in radiotherapy treatments in specific cases.

Who Will Benefit from Charged-Particle Therapy?

Charged-particle therapy (CPT) such as proton beam therapy (PBT) and carbon-ion radiotherapy (CIRT) exhibit substantial physical and biological advantages compared to conventional photon radiotherapy. As it can reduce the amount of radiation irradiated in the normal organ, CPT has been mainly applied to pediatric cancer and radioresistent tumors in the eloquent area. Although there is a possibility of greater benefits, high set-up cost and dearth of high level of clinical evidence hinder wide applications of CPT. This review aims to present recent clinical results of PBT and CIRT in selected diseases focusing on possible indications of CPT. We also discussed how clinical studies are conducted to increase the number of patients who can benefit from CPT despite its high cost.