Concurrent Chemo-Proton Therapy Using Adaptive Planning for Unresectable Stage 3 Non-Small Cell Lung Cancer: A Phase 2 Study

Comparison of deep inspiration breath hold and free breathing intensity modulated proton therapy of locally advanced lung cancer

Background and purpose

For locally advanced non-small cell lung cancer (LA-NSCLC), intensity-modulated proton therapy (IMPT) can reduce organ at risk (OAR) doses compared to intensity-modulated radiotherapy (IMRT). Deep inspiration breath hold (DIBH) reduces OAR doses compared to free breathing (FB) in IMRT. In IMPT, differences in dose distributions and robustness between DIBH and FB are unclear. In this study, we compare DIBH to FB in IMPT, and IMPT to IMRT.

Materials and methods

Fortyone LA-NSCLC patients were prospectively included. 4D computed tomography images (4DCTs) and DIBH CTs were acquired for treatment planning and during weeks 1 and 3 of treatment. A new system for automated robust planning was developed and used to generate a FB and a DIBH IMPT plan for each patient. Plans were compared in terms of dose-volume parameters and normal tissue complication probabilities (NTCPs). Dose recalculations on repeat CTs were used to compare inter-fraction plan robustness.

Results

In IMPT, DIBH reduced median lungs Dmean from 9.3 Gy(RBE) to 8.0 Gy(RBE) compared to FB, and radiation pneumonitis NTCP from 10.9 % to 9.4 % (p < 0.001). Inter-fraction plan robustness for DIBH and FB was similar. Median NTCPs for radiation pneumonitis and mortality were around 9 percentage points lower with IMPT than IMRT (p < 0.001). These differences were much larger than between FB and DIBH within each modality.

Conclusion

DIBH IMPT resulted in reduced lung dose and radiation pneumonitis NTCP compared to FB IMPT. Inter-fraction robustness was comparable. OAR doses were far lower in IMPT than IMRT.

Lobectomy versus proton therapy for stage I non-small cell lung cancer

OBJECTIVE

Lobectomy is the standard treatment for patients with early-stage non-small cell lung cancer (NSCLC). In recent years, an increasing number of patients with lung cancer have been treated using proton therapy (PT). We conducted a propensity score-matched analysis to compare the treatment outcomes of these 2 modalities.

METHODS

We retrospectively reviewed data from 275 patients with histologically confirmed clinical stage I NSCLC who underwent lobectomy (n = 206) or PT (n = 69) at our institution from July 2013 to December 2020. The end points were overall survival (OS), cause-specific survival, recurrence-free survival (RFS), local control, regional lymph node control, and distant control. Propensity score matching was performed to reduce selection bias in the 2 groups.

RESULTS

The matched cohort consisted of 59 patients who underwent lobectomy and 59 patients who underwent PT with a median follow-up period of 50 months. There were no significant differences in OS (P = .26), cause-specific survival (P = .33), RFS (P = .53), local control (P = .41), regional lymph node control (P = .98), and distant control (P = .31). In the lobectomy and PT groups, the 5-year OS rate was 85.8% and 79.1%, respectively, the RFS rate was 82.3% and 77.8%, and the local control rate was 92.1% and 96.6%.

CONCLUSIONS

We found no difference in survival or disease control between lobectomy and PT in patients with histologically confirmed clinical stage I NSCLC. Despite these findings, the potential for unmeasured confounding factors remains, and randomized control trials are needed to better compare these treatment modalities.

Factors related to fixedness after transbronchial fiducial marker placement for image-guided proton therapy: A retrospective study

BACKGROUND

The usefulness of transbronchially inserted gold fiducial markers has been reported in radiation therapy and proton therapy for mobile lesions, such as lung tumors. However, there is occasional dropout of inserted markers. This retrospective study investigated the factors related to dropout of markers inserted for image-guided proton therapy (IGPT).

METHODS

Between June 2013 and October 2021, 535 markers were inserted in 171 patients with lung tumors. We investigated whether marker dropout was affected by the location of marker insertion, distance between the marker and the chest wall (DMC), and difference in forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). Marker dropout from the time of planning computed tomography (CT) to follow-up CT was also evaluated.

RESULTS

Of the 535 inserted markers, 417 were confirmed on planning CT and 356 on follow-up CT after IGPT. Multivariate analysis revealed that marker insertion into the upper lobe and FEV1/FVC ≥70% were factors associated with total marker dropout. Marker dropout between planning CT and follow-up CT was associated with DMC, FEV1/FVC ≥70%, and planning CT performed within 4 days of marker insertion.

CONCLUSIONS

Marker dropout can be minimized by inserting markers more peripherally, by considering the planned insertion location, and FEV1/FVC. Additionally, planning CT should be scheduled at least 5 days after marker insertion.

Efficacy and safety of particle therapy for inoperable stage II-III non-small cell lung cancer: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Particle therapy, mainly including carbon-ion radiotherapy (CIRT) and proton beam therapy (PBT), has dose distribution advantages compared to photon radiotherapy. It has been widely reported as a promising treatment method for early non-small cell lung cancer (NSCLC). However, its application in locally advanced non-small cell lung cancer (LA-NSCLC) is relatively rare, and its efficacy and safety are inconclusive. This study aimed to provide systematic evidence for evaluating the efficacy and safety of particle therapy for inoperable LA-NSCLC.

METHODS

To retrieve published literature, a systematic search was conducted in PubMed, Web of Science, Embase, and Cochrane Library until September 4, 2022. The primary endpoints were local control (LC) rate, overall survival (OS) rate, and progression-free survival (PFS) rate at 2 and 5 years. The secondary endpoint was treatment-related toxicity. The pooled clinical outcomes and 95% confidence intervals (CIs) were calculated by using STATA 15.1.

RESULTS

Nineteen eligible studies with a total sample size of 851 patients were included. The pooled data demonstrated that the OS, PFS, and LC rates at 2 years of LA-NSCLC treated by particle therapy were 61.3% (95% CI = 54.7-68.7%), 37.9% (95% CI = 33.8-42.6%) and 82.2% (95% CI = 78.7-85.9%), respectively. The pooled 5-year OS, PFS, and LC rates were 41.3% (95% CI = 27.1-63.1%), 25.3% (95% CI = 16.3-39.4%), and 61.5% (95% CI = 50.7-74.6%), respectively. Subgroup analysis stratified by treatment type showed that the concurrent chemoradiotherapy (CCRT, PBT combined with concurrent chemotherapy) group had better survival benefits than the PBT and CIRT groups. The incidence rates of grade 3/4 esophagitis, dermatitis, and pneumonia in LA-NSCLC patients after particle therapy were 2.6% (95% CI = 0.4-6.0%), 2.6% (95% CI = 0.5-5.7%) and 3.4% (95% CI = 1.4-6.0%), respectively.

CONCLUSIONS

Particle therapy demonstrated promising efficacy and acceptable toxicity in LA-NSCLC patients.

Clinical results of proton beam radiotherapy for inoperable stage III non-small cell lung cancer: a Japanese national registry study

This study presents the first data of a Japanese nationwide multi-institutional cohort and compares them with the findings of systematic literature reviews on radiation therapies and inoperable stage III non-small cell lung cancer (NSCLC) conducted by the Lung Cancer Working Group in the Particle Beam Therapy (PBT) Committee and Subcommittee at Japanese Society for Radiation Oncology. The Lung Cancer Working Group extracted eight reports and compared their data with those of the PBT registry from May 2016 to June 2018. All the analyzed 75 patients aged ≤80 years underwent proton therapy (PT) with concurrent chemotherapy for inoperable stage III NSCLC. The median follow-up period of the surviving patients was 39.5 (range, 1.6-55.6) months. The 2- and 3-year overall survival (OS) and progression-free survival rates were 73.6%/64.7% and 28.9%/25.1%, respectively. During the follow-up period, six patients (8.0%) had adverse events of Grade ≥ 3, excluding abnormal laboratory values. These included esophagitis in four patients, dermatitis in one and pneumonitis in one. Adverse events of Grade ≥ 4 were not observed. The results of these PBT registry data in patients with inoperable stage III NSCLC suggest that the OS rate was at least equivalent to that of radiation therapy using X-rays and that the incidence of severe radiation pneumonitis was low. PT may be an effective treatment to reduce toxicities of healthy tissues, including the lungs and heart, in patients with inoperable stage III NSCLC.

Recent Advances in Metal-Based NanoEnhancers for Particle Therapy

Radiotherapy is one of the most common therapeutic regimens for cancer treatment. Over the past decade, proton therapy (PT) has emerged as an advanced type of radiotherapy (RT) that uses proton beams instead of conventional photon RT. Both PT and carbon-ion beam therapy (CIBT) exhibit excellent therapeutic results because of the physical characteristics of the resulting Bragg peaks, which has been exploited for cancer treatment in medical centers worldwide. Although particle therapies show significant advantages to photon RT by minimizing the radiation damage to normal tissue after the tumors, they still cause damage to normal tissue before the tumor. Since the physical mechanisms are different from particle therapy and photon RT, efforts have been made to ameliorate these effects by combining nanomaterials and particle therapies to improve tumor targeting by concentrating the radiation effects. Metallic nanoparticles (MNPs) exhibit many unique properties, such as strong X-ray absorption cross-sections and catalytic activity, and they are considered nano-radioenhancers (NREs) for RT. In this review, we systematically summarize the putative mechanisms involved in NRE-induced radioenhancement in particle therapy and the experimental results in in vitro and in vivo models. We also discuss the potential of translating preclinical metal-based NP-enhanced particle therapy studies into clinical practice using examples of several metal-based NREs, such as SPION, Abraxane, AGuIX, and NBTXR3. Furthermore, the future challenges and development of NREs for PT are presented for clinical translation. Finally, we propose a roadmap to pursue future studies to strengthen the interplay of particle therapy and nanomedicine.

Effect of 3-Dimensional Interstitial High-Dose-Rate Brachytherapy With Regional Metastatic Lymph Node Intensity-Modulated Radiation Therapy in Locally Advanced Peripheral Non-Small Cell Lung Cancer: 5-Year Follow-up of a Phase 2 Clinical Trial

PURPOSE

We aimed to reveal the 5-year clinical outcomes of 3-dimensional (3D) interstitial high-dose-rate (HDR) brachytherapy with regional metastatic lymph node intensity modulated radiation therapy (IMRT) for locally advanced peripheral non-small cell lung cancer (NSCLC), which has been shown to have low toxicity and improved 2-year survival rates in patients with this disease.

METHODS AND MATERIALS

In this phase 2, single-arm, open-label clinical trial, 83 patients with locally advanced peripheral NSCLC were enrolled (median follow-up [range], 53.7 [4.3-120.4] months). All eligible patients received 3D interstitial HDR brachytherapy with regional metastatic lymph node IMRT. The primary endpoint was overall survival (OS). Secondary endpoints were local recurrence-free survival, regional recurrence-free survival, progression-free survival, distant metastasis-free survival, toxicities, and quality of life.

RESULTS

The final analysis included 75 patients (19 [25.3%] females, 56 [74.7%] males; median [range] age, 64 [44-80] years; stage IIIA, 34 [45.3%]; stage IIIB, 41 [54.7%]). At the latest follow-up, 32 (42.7%) patients had survived. The median OS was 38.0 months (5-year OS, 44.5%; 95% confidence interval [CI], 33.8%-58.6%). Local recurrence-free survival, recurrence-free survival, and distant metastasis-free survival at 5 years were 79.2% (95% CI, 68.5%-91.5%), 73.6% (95% CI, 61.5%-88.1%), and 50.3% (95% CI, 38.3%-66.1%), respectively. The dominant failure pattern was distant disease, corresponding to 40% (30 of 75) of patients and 65.2% (30 of 46) of all failures. Two (2.7%) patients developed grade 1 acute pneumonitis. Grade 2 and 3 acute esophagitis occurred in 11 (14.7%) and 4 (5.3%) patients, respectively. No late radiation-related grade ≥2 late adverse events were observed.

CONCLUSIONS

3D interstitial HDR brachytherapy with regional metastatic lymph node IMRT for locally advanced peripheral NSCLC shows significant OS and has a low toxicity rate. Additional evaluation in a phase 3 trial is recommended to substantiate these findings.

Combined proton-photon therapy for non-small cell lung cancer

PURPOSE

Advanced non-small cell lung cancer (NSCLC) is still a challenging indication for conventional photon radiotherapy. Proton therapy has the potential to improve outcomes, but proton treatment slots remain a limited resource despite an increasing number of proton therapy facilities. This work investigates the potential benefits of optimally combined proton-photon therapy delivered using a fixed horizontal proton beam line in combination with a photon Linac, which could increase accessibility to proton therapy for such a patient cohort.

MATERIALS AND METHODS

A treatment planning study has been conducted on a patient cohort of seven advanced NSCLC patients. Each patient had a planning CT and multiple repeated CTs from three different days and for different breath-holds on each day. Treatment plans for combined proton-photon therapy (CPPT) were calculated for individual patients by optimizing the combined cumulative dose on the initial planning CT only (non-adapted) as well as on each daily CT respectively (adapted). The impact of inter-fractional changes and/or breath-hold variability was then assessed on the repeat breath-hold CTs. Results were compared to plans for IMRT or IMPT alone, as well as against combined treatments assuming a proton gantry. Plan quality was assessed in terms of dosimetric, robustness and NTCP metrics.

RESULTS

Combined treatment plans improved plan quality compared to IMRT treatments, especially in regard to reductions of low and medium doses to organs at risk (OARs), which translated into lower NTCP estimates for three side effects. For most patients, combined treatments achieved results close to IMPT-only plans. Inter-fractional changes impact mainly the target coverage of combined and IMPT treatments, while OARs doses were less affected by these changes. With plan adaptation however, target coverage of combined treatments remained high even when taking variability between breath-holds into account.

CONCLUSIONS

Optimally combined proton-photon plans improve treatment plan quality compared to IMRT only, potentially reducing the risk of toxicity while also allowing to potentially increase accessibility to proton therapy for NSCLC patients. This article is protected by copyright. All rights reserved.

Imaging Strategies in Proton Therapy for Thoracic Tumors: A Mini Review

Proton beam therapy (PBT) is often more attractive for its high gradient dose distributions than other treatment modalities with external photon beams. However, in thoracic lesions treated particularly with pencil beam scanning (PBS) proton beams, several dosimetric issues are addressed. The PBS approach may lead to large hot or cold spots in dose distributions delivered to the patients, potentially affecting the tumor control and/or increasing normal tissue side effects. This delivery method particularly benefits image-guided approaches. Our paper aims at reviewing imaging strategies and their technological trends for PBT in thoracic lesions. The focus is on the use of imaging strategies in simulation, planning, positioning, adaptation, monitoring, and delivery of treatment and how changes in the anatomy of thoracic tumors are handled with the available tools and devices in PBT. Starting from bibliographic research over the past 5 years, retrieving 174 papers, major key questions, and implemented solutions were identified and discussed; the results aggregated and presented following the methodology of analysis of expert interviews.

Outcomes of proton therapy for non-small cell lung cancer in patients with interstitial pneumonia

Background

Interstitial pneumonia (IP) is a disease with a poor prognosis. In addition, IP patients are more likely to develop lung cancer. Since IP patients frequently develop toxicities during cancer treatment, minimally invasive cancer treatment is warranted for such patients to maintain their quality of life. This study retrospectively investigated the efficacy and safety of proton therapy (PT) for non-small cell lung cancer (NSCLC) in patients with IP.

Methods

Twenty-nine NSCLC patients with IP were treated with PT between September 2013 and December 2019. The patients had stage IA to IIIB primary NSCLC. Ten of the 29 patients exhibited the usual interstitial pneumonia pattern. The prescribed dose was 66–74 Grays (relative biological effectiveness) in 10–37 fractions.

Results

The median follow-up period was 21.1 months [interquartile range (IQR), 15.6–37.3] for all patients and 37.2 months (IQR, 24.0–49.9) for living patients. The median patient age was 77 years (IQR, 71–81). The median planning target volume was 112.0 ml (IQR, 56.1–246.3). The 2-year local control, progression-free survival, and overall survival rates were 85% (95% confidence interval: 57–95), 30% (15–47), and 45% (26–62), respectively. According to the Common Terminology Criteria for Adverse Events (version 4.0), grade 3 acute radiation pneumonitis (RP) was observed in 1 patient. Two patients developed grade 3 late RP, but no other patients experienced serious toxicities. The patients’ quality of life (European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-LC13 and SF-36) scores had not changed after 3 months.

Conclusions

PT may be a relatively safe treatment for NSCLC patients with IP, without deteriorating quality of life scores within 3 months.

Substantial Sparing of Organs at Risk with Modern Proton Therapy in Lung Cancer, but Altered Breathing Patterns Can Jeopardize Target Coverage

Simple Summary

Treatment of locally advanced non-small cell lung cancer (LA-NSCLC) is a fine balance between toxicity and cure. Modern proton therapy might offer a more gentle radiation treatment compared to state-of-the-art photon radiotherapy, but is also more susceptible to the influence of breathing motion and anatomical changes. In this study, the influence of such uncertainties on treatment delivery was thoroughly investigated. Modern proton therapy did indeed show potential to reduce the risk of toxicity for the heart and lungs. This potential was maintained under the influence of anatomical and delivery uncertainties. However, changes in breathing motion jeopardized the target dose distribution in a subset of patients. We therefore recommend imaging at onset or early in treatment to recognize these patients and adapt the treatment.

Abstract

Enhancing treatment of locally advanced non-small cell lung cancer (LA-NSCLC) by using pencil beam scanning proton therapy (PBS-PT) is attractive, but little knowledge exists on the effects of uncertainties occurring between the planning (Plan) and the start of treatment (Start). In this prospective simulation study, we investigated the clinical potential for PBS-PT under the influence of such uncertainties. Imaging with 4DCT at Plan and Start was carried out for 15 patients that received state-of-the-art intensity-modulated radiotherapy (IMRT). Three PBS-PT plans were created per patient: 3D robust single-field uniform dose (SFUD), 3D robust intensity-modulated proton therapy (IMPT), and 4D robust IMPT (4DIMPT). These were exposed to setup and range uncertainties and breathing motion at Plan, and changes in breathing motion and anatomy at Start. Target coverage and dose-volume parameters relevant for toxicity were compared. The organ at risk sparing at Plan was greatest with IMPT, followed by 4DIMPT, SFUD and IMRT, and persisted at Start. All plans met the preset criteria for target robustness at Plan. At Start, three patients had a lack of CTV coverage with PBS-PT. In conclusion, the clinical potential for heart and lung toxicity reduction with PBS-PT was substantial and persistent. Altered breathing patterns between Plan and Start jeopardized target coverage for all PBS-PT techniques.

Dosimetry, Efficacy, Safety, and Cost-Effectiveness of Proton Therapy for Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common malignancy which requires radiotherapy (RT) as an important part of its multimodality treatment. With the advent of the novel irradiation technique, the clinical outcome of NSCLC patients who receive RT has been dramatically improved. The emergence of proton therapy, which allows for a sharper dose of build-up and drop-off compared to photon therapy, has potentially improved clinical outcomes of NSCLC. Dosimetry studies have indicated that proton therapy can significantly reduce the doses for normal organs, especially the lung, heart, and esophagus while maintaining similar robust target volume coverage in both early and advanced NSCLC compared with photon therapy. However, to date, most studies have been single-arm and concluded no significant changes in the efficacy for early-stage NSCLC by proton therapy over stereotactic body radiation therapy (SBRT). The results of proton therapy for advanced NSCLC in these studies were promising, with improved clinical outcomes and reduced toxicities compared with historical photon therapy data. However, these studies were also mainly single-arm and lacked a direct comparison between the two therapies. Currently, there is much emerging evidence focusing on dosimetry, efficacy, safety, and cost-effectiveness of proton therapy for NSCLC that has been published, however, a comprehensive review comparing these therapies is, to date, lacking. Thus, this review focuses on these aspects of proton therapy for NSCLC.

Safety and utility of performing CT-guided biopsies of pulmonary lesions that arise after radiotherapy

This study aimed to evaluate the feasibility, safety and usefulness of performing computed tomography (CT)-guided biopsies of pulmonary lesions that arise after radiotherapy. Seventeen patients (14 males and 3 females; median age: 69 years, range: 48-84 years) underwent CT-guided biopsies of pulmonary lesions that occurred in lung regions that had previously been treated with radiotherapy. Three patients underwent CT-guided biopsies twice, and thus, the total number of procedures was 20. We reviewed the subjects' medical records and images, and evaluated the rate for obtaining pathological diagnosis with the biopsy sample, subsequent clinical course, and complications associated with the procedure. In 19 of 20 procedures (95%), the CT-guided biopsy resulted in a pathological diagnosis being obtained. In 14 procedures, the pathological results were consistent with the patients' clinical courses. In the remaining 5 procedures, the lesions were pathologically diagnosed as benign, but they increased in size thereafter; so the lesions were considered to be clinically malignant. The results were considered to represent sampling errors. There were 3 minor complications (slight pneumothorax which did not require drainage) (3/20, 15%), and there were no major complications. In conclusion, performing CT-guided biopsies of pulmonary lesions that arise after radiotherapy appears to be feasible, safe and useful.