Long Term Results of Single-Fraction Carbon-Ion Radiotherapy for Non-small Cell Lung Cancer

Proton and carbon ion radiotherapy for operable early-stage lung cancer; a prospective nationwide registry

BACKGROUND AND PURPOSE

To investigate the toxicity and survival outcomes of proton and carbon ion radiotherapy for patients with operable early-stage lung cancer who are eligible for lobectomy.

MATERIALS AND METHODS

This multicenter nationwide prospective cohort study included patients with operable early-stage lung cancer. Proton and carbon ion radiotherapy was performed according to the schedule stipulated in the unified treatment policy. Progression-free survival (PFS), overall survival (OS) and treatment-related toxicities were evaluated.

RESULTS

A total of 274 patients were enrolled and included in efficacy and safety analyses. The most common tumor type was adenocarcinoma (44 %), while 105 cases (38 %) were not histologically confirmed or diagnosed clinically. Overall, 250 (91 %) of the 274 patients had tumors that were peripherally situated, while 138 (50 %) and 136 (50 %) patients were treated by proton and carbon ion radiotherapy, respectively. The median follow-up time for all censored patients was 42.8 months (IQR 36.7-49.0). Grade 3 or severe treatment-related toxicity was observed in 4 cases (1.5 %). Three-year PFS was 80.5 % (95 % CI: 75.7 %-85.5 %) and OS was 92.5 % (95 % CI: 89.3 %-95.8 %). Pathological confirmation and clinical stage were factors significantly associated with PFS, while tumor location and particle-ion type were not. Meanwhile, clinical stage was significantly associated with OS, but pathological confirmation, tumor location, and particle-ion type were not.

CONCLUSIONS

Particle therapy for operable early-stage lung cancer resulted in excellent 3-year OS and PFS in each subset. In this disease context, proton and carbon ion beam therapies are feasible alternatives to curative surgery.

Modeling of the resensitization effect on carbon-ion radiotherapy for stage I non-small cell lung cancer

Objective. To investigate the effect of redistribution and reoxygenation on the 3-year tumor control probability (TCP) of patients with stage I non-small cell lung cancer (NSCLC) treated with carbon-ion radiotherapy.Approach. A meta-analysis of published clinical data of 233 NSCLC patients treated by carbon-ion radiotherapy under 18-, 9-, 4-, and single-fraction schedules was conducted. The linear-quadratic (LQ)-based cell-survival model incorporating the radiobiological 5Rs, radiosensitivity, repopulation, repair, redistribution, and reoxygenation, was developed to reproduce the clinical TCP data. Redistribution and reoxygenation were regarded together as a single phenomenon and termed 'resensitization' in the model. The optimum interval time between fractions was investigated for each fraction schedule using the determined model parameters.Main results.The clinical TCP data for 18-, 9-, and 4-fraction schedules were reasonably reproduced by the model without the resensitization effect, whereas its incorporation was essential to reproduce the TCP data for all fraction schedules including the single fraction. The curative dose for the single-fraction schedule was estimated to be 49.0 Gy (RBE), which corresponds to the clinically adopted dose prescription of 50.0 Gy (RBE). For 18-, 9-, and 4-fraction schedules, a 2-to-3-day interval is required to maximize the resensitization effect during the time interval. In contrast, the single-fraction schedule cannot benefit from the resensitization effect, and the shorter treatment time is preferable to reduce the effect of sub-lethal damage repair during the treatment.Significance.The LQ-based cell-survival model incorporating the radiobiological 5Rs was developed and used to evaluate the effect of the resensitization on clinical results of NSCLC patients treated with hypo-fractionated carbon-ion radiotherapy. The incorporation of the resensitization into the cell-survival model improves the reproducibility to the clinical TCP data. A shorter treatment time is preferable in the single-fraction schedule, while a 2-to-3-day interval between fractions is preferable in the multi-fraction schedules for effective treatments.

The rationale for a carbon ion radiation therapy facility in Australia

Australia has taken a collaborative nationally networked approach to achieve particle therapy capability. This supports the under-construction proton therapy facility in Adelaide, other potential proton centres and an under-evaluation proposal for a hybrid carbon ion and proton centre in western Sydney. A wide-ranging overview is presented of the rationale for carbon ion radiation therapy, applying observations to the case for an Australian facility and to the clinical and research potential from such a national centre.

Five-Year Survival Outcomes After Carbon-Ion Radiotherapy for Operable Stage I NSCLC: A Japanese National Registry Study (J-CROS-LUNG)

INTRODUCTION

The standard therapy for stage I NSCLC is surgery, but some operable patients refuse this option and instead undergo radiotherapy. Carbon-ion radiotherapy (CIRT) is a type of radiotherapy. The Japanese prospective nationwide registry study on CIRT began in 2016. Here, we analyzed real-world clinical outcomes of CIRT for operable patients with stage I NSCLC.

METHODS

All patients with operable stage I NSCLC treated with CIRT in Japan between 2016 and 2018 were enrolled. The dose fractionations for CIRT were selected from several options approved by the Japanese Society for Radiation Oncology. CIRT was delivered to the primary tumor, not to lymph nodes.

RESULTS

The median follow-up period was 56 months. Among 136 patients, 117 (86%) had clinical stage IA NSCLC and 19 (14%) had clinical stage IB NSCLC. There were 50 patients (37%) diagnosed clinically without having been diagnosed histologically. Most tumors (97%) were located in the periphery. The 5-year overall survival, cause-specific survival, progression-free survival, and local control rate were 81.8% (95% confidence interval [CI]: 75.1-89.2), 91.2% (95% CI: 86.0-96.8), 65.9% (95% CI: 58.2-74.6), and 95.8% (95% CI: 92.3-99.5), respectively. Multivariate analysis identified age as a significant factor for overall survival (p = 0.018), whereas age and consolidation/tumor ratio (p = 0.010 and p = 0.004) were significant factors for progression-free survival. There was no grade 4 or higher toxicity. Grade 3 radiation pneumonitis occurred in one patient.

CONCLUSIONS

This study reports the long-term outcomes of CIRT for operable NSCLC in the real world. CIRT for operable patients has been found to have favorable outcomes, with tolerable toxicity.

Long-Term Outcomes of Ablative Carbon-Ion Radiotherapy for Central Non-Small Cell Lung Cancer: A Single-Center, Retrospective Study

The aim of this study is to assess the efficacy and safety of ablative carbon ion radiotherapy (CIRT) for early stage central non-small cell lung cancer (NSCLC). We retrospectively reviewed 30 patients who had received CIRT at 68.4 Gy in 12 fractions for central NSCLC in 2006-2019. The median age was 75 years, and the median Karnofsky Performance Scale score was 90%. All patients had concomitant chronic obstructive pulmonary disease, and 20 patients (67%) were considered inoperable. In DVH analysis, the median lung V5 and V20 were 15.5% and 10.4%, and the median Dmax, D0.5cc, D2cc of proximal bronchial tree was 65.6 Gy, 52.8 Gy, and 10.0 Gy, respectively. At a median follow-up of 43 months, the 3-year overall survival, disease-specific survival, and local control rates were 72.4, 75.8, and 88.7%, respectively. Two patients experienced grade 3 pneumonitis, but no grade ≥3 adverse events involving the mediastinal organs occurred. Ablative CIRT is feasible and effective for central NSCLC and could be considered as a treatment option, especially for patients who are intolerant of other curative treatments.

Safety and Efficacy of Single-Fraction Carbon-Ion Radiotherapy for Early-Stage Lung Cancer with Interstitial Pneumonia

Patients with lung cancer complicated by interstitial pneumonia (IP) often lose treatment options early owing to acute exacerbation of IP concerns. Carbon-ion radiotherapy (CIRT) can provide superior tumor control and low toxicity at high dose concentrations. We conducted a retrospective analysis of the efficacy and tolerability of a single-fraction CIRT using 50 Gy for IP-complicated lung cancer. The study included 50 consecutive patients treated between April 2013 and September 2022, whose clinical stage of lung cancer (UICC 7th edition) was 1A:1B:2A:2B = 32:13:4:1. Of these, 32 (64%) showed usual interstitial pneumonia patterns. With a median follow-up of 23.5 months, the 3-year overall survival (OS), cause-specific survival, and local control rates were 45.0, 75.4, and 77.8%, respectively. The median lung V5 and V20 were 10.0 and 5.2%, respectively (mean lung dose, 2.6 Gy). The lung dose, especially lung V20, showed a strong association with OS (p = 0.0012). Grade ≥ 2 pneumonia was present in six patients (13%), including two (4%) with suspected grade 5. CIRT can provide a relatively safe and curative treatment for patients with IP-complicated lung cancer. However, IP increases the risk of severe radiation pneumonitis, and further studies are required to assess the appropriate indications.

Outcomes of carbon ion radiotherapy compared with segmentectomy for ground glass opacity-dominant early-stage lung cancer

PURPOSE

This study aimed to compare the outcomes of patients with ground-grass opacity (GGO)-dominant non-small cell lung cancer (NSCLC) who were treated with carbon ion radiotherapy (CIRT) versus segmentectomy.

METHODS

A retrospective review of medical records was conducted. The study included 123 cases of clinical stage 0/IA peripheral NSCLC treated with single-fraction CIRT from 2003 to 2012, 14 of which were determined to be GGO-dominant and were assigned to CIRT group. As a control, 48 consecutive patients who underwent segmentectomy for peripheral GGO-dominant clinical stage IA NSCLC were assigned to segmentectomy group.

RESULTS

The patients in CIRT group, compared with segmentectomy group, were significantly older (75 ± 7.2 vs. 65 ± 8.2 years, P = 0.000660), more likely to be male (13/14 vs. 22/48, P = 0.00179), and had a lower forced vital capacity (91 ± 19% vs. 110 ± 13%, P = 0.0173). There was a significant difference in the 5-years overall survival rate (86% vs. 96%, P = 0.000860), but not in the 5-years disease-specific survival rate (93% vs. 98%, P = 0.368).

DISCUSSION

Compared with segmentectomy, CIRT may be an alternative option for patients with early GGO-dominant NSCLC who are poor candidates for, or who refuse, surgery.

Creation, evolution, and future challenges of ion beam therapy from a medical physicist's viewpoint (Part 3): Chapter 3. Clinical research, Chapter 4. Future challenges, Chapter 5. Discussion, and Conclusion

Clinical studies of ion beam therapy have been performed at the Lawrence Berkeley Laboratory (LBL), National Institute of Radiological Sciences (NIRS), Gesellschaft für Schwerionenforschung (GSI), and Deutsches Krebsforschungszentrum (DKFZ), in addition to the development of equipment, biophysical models, and treatment planning systems. Although cancers, including brain tumors and pancreatic cancer, have been treated with the Bevalac's neon-ion beam at the LBL (where the first clinical research was conducted), insufficient results were obtained owing to the limited availability of neon-ion beams and immaturity of related technologies. However, the 184-Inch Cyclotron's helium-ion beam yielded promising results for chordomas and chondrosarcomas at the base of the skull. Using carbon-ion beams, NIRS has conducted clinical trials for the treatment of common cancers for which radiotherapy is indicated. Because better results than X-ray therapy results have been obtained for lung, liver, pancreas, and prostate cancers, as well as pelvic recurrences of rectal cancer, the Japanese government recently approved the use of public medical insurance for carbon-ion radiotherapy, except for lung cancer. GSI obtained better results than LBL for bone and soft tissue tumors, owing to dose enhancement enabled by scanning irradiation. In addition, DKFZ compared treatment results of proton and carbon-ion radiotherapy for these tumors. This article summarizes a series of articles (Parts 1-3) and describes future issues of immune ion beam therapy and linear energy transfer optimization.

An international approach to estimating the indications and number of eligible patients for carbon ion radiation therapy (CIRT) in Australia

BACKGROUND AND PURPOSE

To establish the treatment indications and potential patient numbers for carbon ion radiation therapy (CIRT) at the proposed national carbon ion (and proton) therapy facility in the Westmead precinct, New South Wales (NSW), Australia.

METHODS

An expert panel was convened, including representatives of four operational and two proposed international carbon ion facilities, as well as NSW-based CIRT stakeholders. They met virtually to consider CIRT available evidence and experience. Information regarding Japanese CIRT was provided pre- and post- the virtual meeting. Published information for South Korea was included in discussions.

RESULTS

There was jurisdictional variation in the tumours treated by CIRT due to differing incidences of some tumours, referral patterns, differences in decisions regarding which tumours to prioritise, CIRT resources available and funding arrangements. The greatest level of consensus was reached that CIRT in Australia can be justified currently for patients with adenoid cystic carcinomas and mucosal melanomas of the head and neck, hepatocellular cancer and liver metastases, base of skull meningiomas, chordomas and chondrosarcomas. Almost 1400 Australian patients annually meet the consensus-derived indications now.

CONCLUSION

A conservative estimate is that 1% of cancer patients in Australia (or 2% of patients recommended for radiation therapy) may preferentially benefit from CIRT for initial therapy of radiation resistant tumours, or to boost persistently active disease after other therapies, or for re-irradiation of recurrent disease. On this basis, one national carbon ion facility with up to four treatment rooms is justified for Australian patients.

Comparative Analysis of Photon Stereotactic Radiotherapy and Carbon-Ion Radiotherapy for Elderly Patients with Stage I Non-Small-Cell Lung Cancer: A Multicenter Retrospective Study

The emergence of an aging society and technological advances have made radiotherapy, especially stereotactic body radiotherapy (SBRT), a common alternative to surgery for elderly patients with early stage non-small-cell lung cancer (NSCLC). Carbon-ion radiotherapy (CIRT) is also an attractive treatment option with potentially lower toxicity for elderly patients with comorbidities. We compared the clinical outcomes of the two modalities using Japanese multicenter data. SBRT (n = 420) and single-fraction CIRT (n = 70) data for patients with stage I NSCLC from 20 centers were retrospectively analyzed. Contiguous patients ≥ 80 years of age were enrolled, and overall survival (OS), disease-specific survival (DSS), local control (LC), and adverse event rates were compared. The median age was 83 years in both groups and the median follow-up periods were 28.5 and 42.7 months for SBRT and CIRT, respectively. The 3-year OS, DSS, and LC rates were 76.0% vs. 72.3% (p = 0.21), 87.5% vs. 81.6% (p = 0.46), and 79.2% vs. 78.2% (p = 0.87), respectively, for the SBRT vs. CIRT groups. Regarding toxicity, 2.9% of the SBRT group developed grade ≥ 3 radiation pneumonitis, whereas none of the CIRT group developed grade ≥ 2 radiation pneumonitis. SBRT and CIRT in elderly patients showed similar survival and LC rates, although CIRT was associated with less severe radiation pneumonitis.

Experimental Validation of a Real-Time Adaptive 4D-Optimized Particle Radiotherapy Approach to Treat Irregularly Moving Tumors

PURPOSE

Treatment of locally advanced lung cancer is limited by toxicity and insufficient local control. Particle therapy could enable more conformal treatment than intensity modulated photon therapy but is challenged by irregular tumor motion, associated range changes, and tumor deformations. We propose a new strategy for robust, online adaptive particle therapy, synergizing 4-dimensional optimization with real-time adaptive beam tracking. The strategy was tested and the required motion monitoring precision was determined.

METHODS AND MATERIALS

In multiphase 4-dimensional dose delivery (MP4D), a dedicated quasistatic treatment plan is delivered to each motion phase of periodic 4-dimensional computed tomography (4DCT). In the new extension, "MP4D with residual tracking" (MP4DRT), lateral beam tracking compensates for the displacement of the tumor center-of-mass relative to the current phase in the planning 4DCT. We implemented this method in the dose delivery system of a clinical carbon facility and tested it experimentally for a lung cancer plan based on a periodic subset of a virtual lung 4DCT (planned motion amplitude 20 mm). Treatments were delivered in a quality assurance-like setting to a moving ionization chamber array. We considered variable motion amplitudes and baseline drifts. The required motion monitoring precision was evaluated by adding noise to the motion signal. Log-file-based dose reconstructions were performed in silico on the entire 4DCT phantom data set capable of simulating nonperiodic motion. MP4DRT was compared with MP4D, rescanned beam tracking, and internal target volume plans. Treatment quality was assessed in terms of target coverage (D95), dose homogeneity (D5-D95), conformity number, and dose to heart and lung.

RESULTS

For all considered motion scenarios and metrics, MP4DRT produced the most favorable metrics among the tested motion mitigation strategies and delivered high-quality treatments. The conformity was similar to static treatments. The motion monitoring precision required for D95 >95% was 1.9 mm.

CONCLUSIONS

With clinically feasible motion monitoring, MP4DRT can deliver highly conformal dose distributions to irregularly moving targets.

Clinical results of carbon ion radiotherapy for inoperable stage I non-small cell lung cancer: a Japanese national registry study (J-CROS-LUNG)

BACKGROUND AND PURPOSE

Radiotherapy is a standard treatment for inoperable stage I non-small cell lung cancer (NSCLC), and carbon-ion radiation therapy (CIRT) may be used for such treatment. Although CIRT for stage I NSCLC has demonstrated favorable outcomes in previous reports, the reports covered only single-institution studies. We conducted a prospective nationwide registry study including all CIRT institutions in Japan.

MATERIALS AND METHODS

Ninety-five patients with inoperable stage I NSCLC were treated by CIRT between May 2016 and June 2018. The dose fractionations for CIRT were selected from several options approved by the Japanese Society for Radiation Oncology.

RESULTS

The median patient age was 77 years. Comorbidity rates for chronic obstructive pulmonary disease and interstitial pneumonia were 43% and 26%, respectively. The most common schedule for CIRT was 60 Gy (relative biological effectiveness (RBE)) in four fractions, and the second most common was 50 Gy (RBE) in one fraction. The 3-year overall survival, cause-specific survival, and local control rates were 59.3%, 77.1%, and 87.3%, respectively. Female sex and ECOG performance status of 0-1 were favorable prognostic factors for overall survival in a multivariate analysis. No grade 4 or higher adverse event was observed. The 3-year cumulative incidence of grade 2 or higher radiation pneumonitis was 3.2%. The risk factors for radiation pneumonitis were a forced expiratory volume in 1 second (FEV1) of <0.9L and a total dose[[EQUATION]]67 Gy (RBE).

CONCLUSION

This study provides real-world treatment outcomes of CIRT for inoperable stage I NSCLC in Japan.

Basic and translational research on carbon-ion radiobiology

Carbon-ion beam irradiation (IR) has evident advantages over the conventional photon beams in treating tumors. It releases enormous amount of energy in a well-defined range with insignificant scatter in surrounding tissues based on well-localized energy deposition. Over the past 28 years, more than 14,000 patients with various types of cancer have been treated by carbon ion radiotherapy (CIRT) with promising results at QST. I have provided an overview of the basic and translational research on carbon-ion radiobiology including mechanisms underlying high linear energy transfer (LET) carbon-ion IR-induced cell death (apoptosis, autophagy, senescence, mitotic catastrophe etc.) and high radiocurability produced by carbon-ion beams in combination with DNA damaging drugs or with molecular-targeted drugs, micro-RNA therapeutics and immunotherapy. Additionally, I have focused on the application of these treatment in human cancer cells, especially cancer stem cells (CSCs). Finally, I have summarized the current studies on the application of basic carbon-ion beam IR according to the cancer types and clinical outcomes.

Value of carbon-ion radiotherapy for early stage non-small cell lung cancer

Carbon-ion radiotherapy (CIRT) is an important part of modern radiotherapy. Compared to conventional photon radiotherapy modalities, CIRT brings two major types of advantages to physical and biological aspects respectively. The physical advantages include a substantial dose delivery to the tumoral area and a minimization of dose damage to the surrounding tissue. The biological advantages include an increase in double-strand breaks (DSBs) in DNA structures, an upturn in oxygen enhancement ratio and an improvement of radiosensitivity compared with X-ray radiotherapy. The two advantages of CIRT are that the therapy not only inflicts major cytotoxic lesions on tumor cells, but it also protects the surrounding tissue. According to annual diagnoses, lung cancer is the second most common cancer worldwide, followed by breast cancer. However, lung cancer is the leading cause of cancer death. Patients with stage I non-small cell lung cancer (NSCLC) who are optimally received the treatment of lobectomy. Some patients with comorbidities or combined cardiopulmonary insufficiency have been shown to be unable to tolerate the treatment when combined with surgery. Consequentially, radiotherapy may be the best treatment option for this patient category. Multiple radiotherapy options are available for these cases, such as stereotactic body radiotherapy (SBRT), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT). Although these treatments have brought some clinical benefits to some patients, the resulting adverse events (AEs), which include cardiotoxicity and radiation pneumonia, cannot be ignored. The damage and toxicity to normal tissue also limit the increase of tumor dose. Due to the significant physical and biological advantages brought by CIRT, some toxicity induced by radiotherapy may be avoided with CIRT Bragg Peak. CIRT brought clinical benefits to lung cancer patients, especially geriatric patients. This review introduced the clinical efficacy and research results for non-small cell lung cancer (NSCLC) with CIRT.

Research Progress of Heavy Ion Radiotherapy for Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) has a high incidence and poses a serious threat to human health. However, the treatment outcomes of concurrent chemoradiotherapy for non-small-cell lung cancer are still unsatisfactory, especially for high grade lesions. As a new cancer treatment, heavy ion radiotherapy has shown promising efficacy and safety in the treatment of non-small-cell lung cancer. This article discusses the clinical progress of heavy ion radiotherapy in the treatment of non-small-cell lung cancer mainly from the different cancer stages, the different doses of heavy ion beams, and the patient's individual factors, and explores the deficiency of heavy ion radiotherapy in the treatment of non-small-cell lung cancer and the directions of future research, in order to provide reference for the wider and better application of heavy ion radiotherapy in the future.

Robust Angle Selection in Particle Therapy

The popularity of particle radiotherapy has grown exponentially over recent years owing to the marked advantage of the depth–dose curve and its unique biological property. However, particle therapy is sensitive to changes in anatomical structure, and the dose distribution may deteriorate. In particle therapy, robust beam angle selection plays a crucial role in mitigating inter- and intrafractional variation, including daily patient setup uncertainties and tumor motion. With the development of a rotating gantry, angle optimization has gained increasing attention. Currently, several studies use the variation in the water equivalent thickness to quantify anatomical changes during treatment. This method seems helpful in determining better beam angles and improving the robustness of planning. Therefore, this review will discuss and summarize the robust beam angles at different tumor sites in particle radiotherapy.

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.

The Risk Factors for Radiation Pneumonitis After Single-Fraction Carbon-Ion Radiotherapy for Lung Cancer or Metastasis

There are no studies on the risk factors of radiation pneumonitis (RP) after carbon-ion radiotherapy at a dose of 50 Gy (relative biological effectiveness (RBE)) in a single fraction. The objective of this study was to identify factors associated with RP after radiotherapy, including dose-volume parameters. Ninety-eight patients without a history of thoracic radiotherapy who underwent treatment for solitary lung tumors between July 2013 and April 2016 were retrospectively analyzed. Treatment was planned using Xio-N. The median follow-up duration was 53 months, and the median clinical target volume was 32.3 mL. Three patients developed grade 2 RP, and one patient developed grade 3 interstitial pneumonitis. None of the patients developed grade 4 or 5 RP. The dose-volume parameters of the normal lung irradiated at least with 5-30 Gy (RBE), and the mean lung dose was significantly lower in patients with grade 0-1 RP than in those with grade 2-3 RP. Pretreatment with higher SP-D and interstitial pneumonitis were significant factors for the occurrence of symptomatic RP. The present study showed a certain standard for single-fraction carbon-ion radiotherapy that does not increase the risk of RP; however, further validation studies are needed.