Re-irradiation for locoregionally recurrent tumors of the thorax: a single-institution, retrospective study

Lung cancer reirradiation: Exploring modifications to utilization, treatment modalities and factors associated with outcomes

BACKGROUND

Patients treated for lung cancer (LC) often experience locoregional failure after initial treatment. Due to technological advances, thoracic reirradiation (re-RT) has become a viable treatment option. We sought to investigate the use of thoracic re-RT in LC patients over a time period characterized by technological advances in a large, multi-center cohort.

METHODS AND MATERIALS

LC patients treated with thoracic re-RT in two University Hospitals from 2010-2020 were identified. Clinical variables and RT data were extracted from the medical records and treatment planning systems. Overall survival (OS) was calculated from the last day of re-RT until death or last follow up.

RESULTS

296 patients (small cell LC n=30, non-small cell LC n=266) were included. Three-dimensional conformal radiation therapy was the RT technique used most frequently (63%), and 86% of all patients were referred for re-RT with palliative treatment intent. During the second half of the study period, the use of thoracic re-RT increased in general, more patients received curative re-RT, and there was an increased use of stereotactic body radiation therapy (SBRT). Median time between initial RT and re-RT was 18 months (range 1-213 months). Only 83/296 patients had combined treatment plans that allowed for registration of combined doses to organs at risk (OAR). Most of the combined doses to OAR were below recommendations from guidelines. Multivariate analysis showed superior OS (p<0.05) in patients treated with curative intent, SBRT or intensity modulated radiation therapy or had excellent performance status prior to re-RT.

CONCLUSIONS

The use of re-RT increased in the second half of the study period, although 2020 did not follow the trend. The use of SBRT and IMRT became more frequent over the years, yet the majority received palliative re-RT. Combined dose plans were only created for one third of the patients.

REPeated mAgnetic resonance Image-guided stereotactic body Radiotherapy (MRIg-reSBRT) for oligometastatic patients: REPAIR, a mono-institutional retrospective study

BACKGROUND

Oligo-progression or further recurrence is an open issue in the multi-integrated management of oligometastatic disease (OMD). Re-irradiation with stereotactic body radiotherapy (re-SBRT) technique could represent a valuable treatment option to improve OMD clinical outcomes. MRI-guided allows real-time visualization of the target volumes and online adaptive radiotherapy (oART). The aim of this retrospective study is to evaluate the efficacy and toxicity profile of MRI-guided repeated SBRT (MRIg-reSBRT) in the OMD setting and propose a re-SBRT classification.

METHODS

We retrospectively analyzed patients (pts) with recurrent liver metastases or abdominal metastatic lesions between 1 and 5 centimeters from liver candidate to MRIg-reSBRT showing geometric overlap between the different SBRT courses and assessing whether they were in field (type 1) or not (type 2).

RESULTS

Eighteen pts completed MRIg-reSBRT course for 25 metastatic hepatic/perihepatic lesions from July 2019 to January 2020. A total of 20 SBRT courses: 15 Type 1 re-SBRT (75%) and 5 Type 2 re-SBRT (25%) was delivered. Mean interval between the first SBRT and MRIg-reSBRT was 8,6 months. Mean prescribed dose for the first treatment was 43 Gy (range 24-50 Gy, mean BEDα/β10=93), while 41 Gy (range 16-50 Gy, mean BEDα/β10=92) for MRIg-reSBRT. Average liver dose was 3,9 Gy (range 1-10 Gy) and 3,7 Gy (range 1,6-8 Gy) for the first SBRT and MRIg-reSBRT, respectively. No acute or late toxicities were reported at a median follow-up of 10,7 months. The 1-year OS and PFS was 73,08% and 50%, respectively. Overall Clinical Benefit was 54%.

CONCLUSIONS

MRIg-reSBRT could be considered an effective and safe option in the multi-integrated treatment of OMD.

Pretreatment 18-FDG-PET/CT parameters can serve as prognostic imaging biomarkers in recurrent NSCLC patients treated with reirradiation-chemoimmunotherapy

BACKGROUND AND PURPOSE

Our study aimed to assess whether quantitative pretreatment 18F-FDG-PET/CT parameters could predict prognostic clinical outcome of recurrent NSCLC patients who may benefit from ablative reirradiation.

MATERIALS AND METHODS

Forty-eight patients with recurrent NSCLC of all UICC stages who underwent ablative thoracic reirradiation were analyzed. Twenty-nine (60%) patients received immunotherapy with or without chemotherapy in addition to reirradiation. Twelve patients (25%) received reirradiation only and seven (15%) received chemotherapy and reirradiation. Pretreatment 18-FDG-PET/CT was mandatory in initial diagnosis and recurrence, based on which volumetric and intensity quantitative parameters were measured before reirradiation and their impact on overall survival, progression-free survival, and locoregional control was assessed.

RESULTS

With a median follow-up time of 16.7 months, the median OS was 21.8 months (95%-CI: 16.2-27.3). On multivariate analysis, OS and PFS were significantly influenced by MTV (p < 0.001 for OS; p = 0.006 for PFS), TLG (p < 0.001 for OS; p = 0.001 for PFS) and SUL peak (p = 0.0024 for OS; p = 0.02 for PFS) of the tumor and MTV (p = 0.004 for OS; p < 0.001 for PFS) as well as TLG (p = 0.007 for OS; p = 0.015 for PFS) of the metastatic lymph nodes. SUL peak of the tumor (p = 0.05) and the MTV of the lymph nodes (p = 0.003) were only PET quantitative parameters that significantly impacted LRC.

CONCLUSION

Pretreatment tumor and metastastic lymph node MTV, TLG and tumor SUL peak significantly correlated with clinical outcome in recurrent NSCLC patients treated with reirradiation-chemoimmunotherapy.

Re-irradiation for intra-thoracic tumours and extra-thoracic breast cancer: dose accumulation, evaluation of efficacy and toxicity based on a literature review

The improvement seen in the diagnostic procedures and treatment of thoracic tumours means that patients have an increased chance of longer overall survival. Nevertheless, we can still find those who have had a recurrence or developed a secondary cancer in the previously treated area. These patients require retreatment including re-irradiation. We have reviewed the published data on thoracic re-irradiation, which shows that some specific healthy tissues can tolerate a significant dose of irradiation and these patients benefit from aggressive treatment; however, there is a risk of damage to normal tissue under these circumstances. We analysed the literature data on re-irradiation in the areas of vertebral bodies, spinal cord, breast, lung and oesophagus. We evaluated the doses of primary and secondary radiotherapy, the treatment techniques, as well as the local control and median or overall survival in patients treated with re-radiation. The longest OS is reported in the case of re-irradiation after second breast-conserving therapy where the 5-year OS range is 81 to 100% and is shorter in patients with loco-reginal re-irradiation where the 5-y OS range is 18 to 60%. 2-year OS in patients re-irradiated for lung cancer and oesophagus cancer range from 13 to 74% and 18 to 42%, respectively. Majority grade ≥3 toxicity after second breast-conserving therapy was fibrosis up to 35%. For loco-regional breast cancer recurrences, early toxicity occurred in up to 33% of patients resulting in mostly desquamation, while late toxicity was recorded in up to 23% of patients and were mostly ulcerations. Early grade ≥3 lung toxicity developed in up to 39% of patients and up to 20% of Grade 5 hemoptysis. The most frequently observed early toxicity grade ≥3 in oesophageal cancer was oesophagitis recorded in up to 57% of patients, followed by hematological complications which was recorded in up to 50% of patients. The most common late complications included dysphagia, recorded in up to 16.7% of patients. We have shown that thoracic re-irradiation is feasible and effective in achieving local control in some patients. Re-irradiation should be performed with maximum accuracy and care using the best available treatment methods with a highly conformal, image-guided approach. Due to tremendous technological progress in the field of radiotherapy, we can deliver radiation precisely, shorten the overall treatment time and potentially reduce treatment-related toxicities.

Thoracic re-irradiation with 3D-conformal or more advanced techniques: A systematic review of treatment safety by the Re-irradiation Study Group of the Italian Association of Radiation and Oncology AIRO

Re-irradiation (re-RT) is a treatment modality that has been actively investigated in recurrent lung cancer or in lung metastases appeared in previously irradiated areas. A literature search, according PRISMA recommendations and a meta-analysis technique were performed with the aims to identify possible factors related to the toxicity incidence and severity of ≥ G3 acute toxicity. 1243 patients and 36 studies, met inclusion criteria. Our results, showed that there was no difference in ≥ G3 acute (10,5%) toxicity rate with respect to different radiation techniques, cumulative dose and re-irradiation total dose and fractionation. Factors eventually related to severe toxicity were described. The frequent lack of a sufficient description of the treatment's intent, the heterogeneity in technique and radiotherapy regimen, makes balancing risk and benefit of re-RT based on published data even more difficult.

Re-Irradiation for Locally Recurrent Lung Cancer: A Single Center Retrospective Analysis

The treatment of locally recurrent lung cancer is a major challenge for radiation-oncologists, especially with data on high-dose reirradiation being limited to small retrospective studies. The aim of the present study is to assess overall survival (OS) for patients with locally recurrent lung cancer after high-dose thoracic reirradiation. Thirty-nine patients who were re-irradiated for lung cancer relapse between October 2013 and February 2019 were eligible for the current retrospective analysis. All patients were re-irradiated with curative intent for in-field tumor recurrence. The diagnostic work-up included a mandatory ¹⁸F-FDG-PET-CT scan and—if possible—histological verification. The ECOG was ≤2, and the interval between initial and second radiation was at least nine months. Thirty patients (77%) had non-small cell lung cancer (NSCLC), eight (20%) had small cell lung cancer (SCLC), and in one patient (3%) histological confirmation could not be obtained. More than half of the patients (20/39, 51%) received re-treatment with dose differentiated accelerated re-irradiation (DART) at a median interval of 20.5 months (range: 6–145.3 months) after the initial radiation course. A cumulative EQD₂ of 131 Gy (range: 77–211 Gy) in a median PTV of 46 mL (range: 4–541 mL) was delivered. Patients with SCLC had a 3 mL larger median re-irradiation volume (48 mL, range: 9–541) compared to NSCLC patients (45 mL, range: 4–239). The median cumulative EQD2 delivered in SCLC patients was 84 Gy (range: 77–193 Gy), while NSCLC patients received a median cumulative EQD2 of 135 Gy (range: 98–211 Gy). The median OS was 18.4 months (range: 0.6–64 months), with tumor volume being the only predictor (p < 0.000; HR 1.007; 95%-CI: 1.003–1.012). In terms of toxicity, 17.9% acute and 2.6% late side effects were observed, with a toxicity grade >3 occurring in only one patient. Thoracic high dose reirradiation plays a significant role in prolonging survival, especially in patients with small tumor volume at recurrence.

Re-Irradiation of Recurrent Non-Small Cell Lung Cancer

Locoregional recurrence occurs in 10%-30% of non-small cell lung cancer (NSCLC) after treatment with definitive (chemo)radiotherapy. Re-irradiation is the main curative-intent treatment option for these patients; however, it represents a therapeutic challenge for thoracic radiation oncologists. Re-irradiation practices are variable worldwide with lack of agreement on the optimal dose or the cumulative maximum dose acceptable for critical organs. The role of re-irradiation in NSCLC is also not clearly defined in the era of immunotherapy. In this review, we will present published and on-going re-irradiation studies for recurrent NSCLC. We will appraise available evidence for critical organ dose constraints and provide a framework for future therapeutic approaches and trials.

Complex Clinical Decision-Making Process of Re-Irradiation

As patients live longer with their cancer as a result of more effective treatment, recurrences and second malignancies in a previously irradiated field are an increasing challenge. The technical advances that enable high-dose radiation to limited volumes, excluding critical normal tissues, have increased the use of re-irradiation for many tumour sites. Minimising the volume, selecting patients with good performance status, negative metastatic screening and longer disease-free intervals are important principles. Despite this there is a narrow therapeutic window, and careful consideration with open discussion, including the patient, of the probable benefit and the implications of potential toxicities will always be essential. In this overview we evaluate the various radiobiological factors that need to be considered for re-irradiation, tissue recovery and dose tolerances in the setting of re-irradiation and summarise the available literature to guide clinicians in their decision-making for re-irradiation to primary and metastatic site/s of disease.

Re-irradiation in the thorax - An analysis of efficacy and safety based on accumulated EQD2 doses

INTRODUCTION

Thoracic re-irradiation remains a challenge regarding the balance of local efficacy and acceptable toxicities. In this retrospective analysis we analyzed dosimetrical and clinical data of patients treated with thoracic re-irradiation based on accumulated EQD2Gy doses.

METHODS AND MATERIAL

We retrospectively analyzed the data of 42 consecutive single-institutional patients treated with repeated courses of thoracic radiotherapy from 12/2011 to 01/2017. Accumulated EQD2 dose distributions were calculated and dose parameters for organs at risk and target volumes were analysed.

RESULTS

The median prescription dose was 42.2 Gy (10-70.6 Gy) for all RT courses. The median Dmean of both lungs was 10.1 Gy₃ (range: 1.9 Gy₃-17.9 Gy₃) with a maximum D0.1 cc of 253.86 Gy₃. The median D0.1 cc of the esophagus was 62.2 Gy₃ with a maximum of 103.78 Gy₃. The maximum D0.1 cc for the bronchial tree was 187.33 Gy₃ (median 74.35 Gy₃) and for the Aorta 216.1 Gy₃ (median 70.9 Gy₃). Median OS after first re-irradiation was 19 months (range 1-45 months). 12-month local control after a course of re-irradiation was 52.6%. 80% of patients suffered from a G1-G2 toxicity, most frequently coughing. One patient suffered from a G5 complication probably unrelated to re-irradiation.

CONCLUSION

Even though several organs at risk received maximum accumulated doses of >100 Gy₃, thoracic reirradiation resulted in an acceptable toxicity profile. Local tumor control and overall survival remained encouraging even after multiple courses of thoracic radiotherapy.

What is the role of reirradiation in the management of locoregionally relapsed non small-cell lung cancer?

The prognosis of lung cancer patients has improved in the last few years. Despite definitive therapy, local recurrence or a second primary tumour can occur in many patients within previously irradiated areas. Recent developement of more accurate techniques in radiation oncology allows delivery of high radiation dose to the tumor with the aim of improving local control, delaying disease progression and in some cases even curing. Nevertheless, the use of high dose in the reirradiation setting is not without risks, especially when treatment volumes overlap with previously irradiated tissues. The risk of adverse effects must be balanced with the choice of an effective treatment by selecting suitable candidates and the best radiation technique. In this systemic review efficacy and toxicity of reirradiation in locoregionally recurrent non-small-cell lung cancer is extensively discussed. Results indicate that reirradiation might be beneficial in well-selected patients. Prospective and high quality studies are necessary in this field.

Clinical outcomes and toxicity predictors of thoracic re-irradiation for locoregionally recurrent lung cancer

Background and purpose

Thoracic re-irradiation may be an alternative treatment for lung cancer patients who develop intrathoracic locoregional recurrence without systemic progression. This study aimed to retrospectively assess locoregional control, clinical outcomes, and toxicities in lung cancer patients who received thoracic re-irradiation.

Materials and methods

We retrospectively reviewed 50 lung cancer patients who received thoracic re-irradiation using conventional photon radiotherapy (RT) and stereotactic body radiotherapy (SBRT) between 2009 and 2017. The correlations of clinicopathologic factors, treatment factors, and dosimetric factors of RT with time to local progression (TTLP), progression-free survival (PFS), and overall survival (OS) after starting thoracic re-irradiation were calculated using log-rank tests and Cox regression models.

Results

The median re-irradiation dose in equivalent dose in 2-Gy fractions was 51.1 Gy, and the mean re-irradiation planning target volume was 201.58 ml. The median mean lung dose (MLD) was 4.18 Gy, and the total lung volumes receiving a dose of 5 Gy (lung V5) and of 20 Gy (V20) were 19.8% and 5.85%, respectively. The TTLP, PFS, and OS were 18.0, 5.9, and 25.1 months, respectively. Lung V5 (p < 0.001), V20 (p = 0.011), and MLD (p = 0.002) were significantly associated with grade ≥2 lung toxicity. Seven (14%) patients developed lethal lung events. Subsequent chemotherapy following thoracic re-irradiation was significantly correlated with lethal lung events (p = 0.009).

Conclusion

Promising local control can be achieved with thoracic re-irradiation in lung cancer patients with locoregional recurrence. However, unexpected lethal lung events may occur, especially in patients receiving systemic therapy following thoracic re-irradiation.

Prognostic factors and outcome of reirradiation for locally recurrent small cell lung cancer-a multicenter study

Background

The prognosis of patients with recurrent small cell lung cancer (SCLC) remains poor and treatment options are limited. We performed a multi-institution retrospective cohort study to evaluate the outcome of thoracic reirradiation, identify prognostic factors and assess treatment-related toxicity.

Methods

Data of 33 patients re-irradiated for recurrent SCLC at 4 international university hospitals, were analysed. Overall survival (OS) acute and late toxicities were evaluated and prognostic factors for reirradiation were identified.

Results

Reirradiation (Re-RT) was performed at a median interval time of 24 months after the first thoracic radiotherapy series. Median survival after reirradiation was 7 months (range, 1-54 months). The Re-RT dose in EQD2 ranged from 20 to 87.50 Gy with a median of 32.50 Gy. The 1- and 2-year OS were 33% and 17%, respectively. Patients with a good performance status (KPS >70%), absence of extrathoracic disease, reirradiation dose (EQD2) of >40 Gy and a cumulative dose of first plus second series of radiotherapy (EQD2) >90 Gy were associated with improved OS. Acute pulmonary Grade 1-2 toxicity from re-irradiation was recorded in 11 patients (33%) and grade 3 acute toxicity was encountered 1 patient (3%).

Conclusions

Reirradiation for locoregionally recurrent SCLC is safe and shows promising outcomes. Patients reirradiated with doses >40 Gy experienced more favourable survival rates. In contrast, patients with a poor performance status or extrathoracic disease have a poor prognosis and Re-RT should be considered only for symptom control in this group.

High-Dose Thoracic Re-irradiation of Lung Cancer Using Highly Conformal Radiotherapy Is Effective with Acceptable Toxicity

Purpose

Thoracic re-irradiation (re-RT) of lung cancer has been challenged by the tolerance doses of normal tissues. We retrospectively analyzed local control, overall survival (OS) and toxicity after thoracic re-RT using highly conformal radiotherapy, such as intensity modulated radiotherapy and stereotactic body radiotherapy.

Materials and Methods

Thirty-one patients who received high-dose thoracic re-RT were analyzed. Doses were recalculated to determine biologically equivalent doses. The median interval to re-RT was 15.1 months (range, 4.4 to 56.3 months), the median initial dose was 79.2 Gy₁₀ (range, 51.75 to 150 Gy₁₀), and the median re-RT dose was 68.8 Gy₁₀ (range, 43.2 to 132 Gy₁₀).

Results

Eighteen (58.1%) and eleven (35.5%) patients showed loco-regional recurrence and distant metastasis, respectively, after 17.4 months of median follow-up. The 1-year and 2-year local control rates were 60.2% and 43.7%, respectively. The median loco-regional recurrence-free-survival (LRFS) was 15.4 months, and the median OS was 20.4 months. The cumulative and re-RT biologically equivalent dose for α/β=10 (BED₁₀) doses were the most significant prognostic factors. Cumulative BED₁₀ ≥145 Gy₁₀ and re-RT BED₁₀≥68.7 Gy₁₀ were significantly associated with longer OS (p=0.029 and p=0.012, respectively) and LRFS (p=0.003 and p=0.000, respectively). The most frequent acute toxicity was grade 1-2 pulmonary toxicity (41.9%). No acute grade 3 or higher toxicities occurred.

Conclusion

Our results show that high-dose thoracic re-RT of lung cancer can be safely delivered using highly conformal radiotherapy with favorable survival and acceptable toxicity. An optimal strategy to select patients who would benefit from re-RT is crucial in extending the indications and improving the efficacy with a sufficiently high dose.

Survival benefit of re-irradiation in esophageal Cancer patients with Locoregional recurrence: a propensity score-matched analysis

BACKGROUND

To investigate the treatment failure pattern and factors influencing locoregional recurrence of esophageal squamous cell carcinoma (ESCC) and examine patient survival with re-irradiation (re-RT) after primary radiotherapy.

METHODS

We retrospectively analyzed 87 ESCC patients treated initially with radiotherapy. Failure patterns were classified into regional lymph node recurrence only (LN) and primary failure with/without regional lymph node recurrence (PF). Patients received either re-RT or other treatments (non-re-RT group). Baseline covariates were balanced by a propensity score model. Overall survival (OS) and toxicities were assessed as outcomes.

RESULTS

The median follow-up time was 87 months. Thirty-nine patients received re-RT. Failure pattern and re-RT were independent prognostic factors for OS (P = 0.040 and 0.015) by Cox multivariate analysis. Re-RT with concomitant chemotherapy showed no survival benefit over re-RT alone (P = 0.70). No differences in characteristics were found between the groups by Chi-square tests after propensity score matching. The Cox model showed that failure pattern and re-RT were prognostic factors with hazard ratios (HR) of 0.319 (P = 0.025) and 0.375 (P = 0.002), respectively, in the matched cohort. Significant differences in OS were observed according to failure pattern (P = 0.004) and re-RT (P < 0.001). In the re-RT and non-re-RT groups, 9.09% and 3.03% of patients experienced tracheoesophageal fistulas, and 15.15% and 3.03% of patients developed pericardial/pleural effusion, respectively (P > 0.05). The incidence of radiation pneumonitis was higher in the re-RT group (24.24% vs. 6.06%, P = 0.039), but no cases of pneumonia-related death occurred.

CONCLUSIONS

Re-RT improved long-term survival in patients with locoregional recurrent ESCC. Despite a high incidence of radiation pneumonitis, toxicities were tolerable.

Re-irradiation in lung disease by SBRT: a retrospective, single institutional study

BACKGROUND

The loco regional relapse is frequent in the lung disease. The aim of this study was to evaluate the outcomes of re-irradiation by SBRT in terms of Local Control (LC) and toxicities.

METHODS

From April 2011 to December 2016, twenty-two patients received a re-irradiation by SBRT. Twenty- seven lesions were treated. The medium BED(10) of re-irradiation was 100.6 Gy (range: 48-151.2 Gy) and the medium EQD2(10) was 93.8 Gy (range: 40-126 Gy). In the previous treatment the medium BED(10) was 97.2 Gy (range: 40-120 Gy), the medium EQD2(10) was 81 Gy (range: 32.5-100 Gy). The median time between the first and the second treatment was 18 months.

RESULTS

Local Control was reached in 18 out of 27 (66%) re-irradiated lesions, with rates of 67 and 54% at 1- year and 2- years respectively. The treatment was well tolerated; the maximum recorded toxicity was Grade 3.

CONCLUSIONS

Re- irradiation by SBRT may represent an option for the treatment of lung disease with good results in terms of LC and toxicity.

The risk and predictors for severe radiation pneumonitis in lung cancer patients treated with thoracic reirradiation

BACKGROUND

Thoracic reirradiation (re-RT) is increasingly administered. However, radiation pneumonitis (RP) remains to be the most common side effect from retreatment. This study aimed to determine the risk and predictors for severe RP in patients receiving thoracic re-RT.

METHODS

Sixty seven patients with lung cancer received thoracic re-RT for recurrent or metastatic disease. Three-dimensional conformal radiotherapy (3D-CRT)/intensity modulated radiotherapy (IMRT) was used for 60 patients, and stereotactic body radiation therapy (SBRT) was used in 7 patients. Deformable image registration (DIR) was performed to create a composite plan. Severe (grade ≥ 3) RP was graded according to Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

Eighteen patients (26.9%) developed grade ≥ 3 RP (17 of grade 3, and 1 of grade 4). In univariate analyses, V5 and mean lung dose (MLD) of initial RT or re-RT plans, V5 and V20 of composite plans, and the overlap between V5 of initial RT and V5 of re-RT plans/V5 of re-RT plans (overlap-V5/re-V5) were significantly associated with grade ≥ 3 RP (P < 0.05 for each comparison). Multivariate analysis revealed that MLD of the initial RT plans (HR = 14.515, 95%CI:1.778-118.494, P = 0.013), V5 of the composite plans (HR = 7.398, 95%CI:1.319-41.495, P = 0.023), and overlap-V5/re-V5 (P = 0.041) were independent predictors for grade ≥ 3 RP. Out-of-field failures with medium overlap-V5/re-V5 of 0.4-0.8 was associated with higher risk of grade ≥ 3 RP compared with in-field failures (18.3% vs. 50%, P = 0.014).

CONCLUSIONS

The risk of grade ≥ 3 RP could be predicted not only by dose-volume variables from re-RT plan, but also by some from initial-RT and composite plans. Out-of-field failures was associated with higher risk of severe RP compared with in-field failures in some cases.

Re-irradiation for Locally Recurrent Lung Cancer: Evidence, Risks and Benefits

In spite of recent improvements in both the technical delivery of radiotherapy and systemic therapy in the treatment of non-small cell lung cancer, local recurrence rates after radiotherapy remain a significant challenge. In the setting of local relapse after radiotherapy, treatments such as surgical resection or radiofrequency ablation are often not appropriate owing to disease and patient factors. Re-irradiation may be a potential treatment option. This overview considers the published evidence and potential treatment strategies.

Proton beam therapy in non-small cell lung cancer: state of the art

This review summarizes the past and present status of proton beam therapy (PBT) for lung cancer. PBT has a unique characteristic called the Bragg peak that enables a reduction in the dose of normal tissue around the tumor, but is sensitive to the uncertainties of density changes. The heterogeneity in electron density for thoracic lesions, such as those in the lung and mediastinum, and tumor movement according to respiration necessitates respiratory management for PBT to be applied in lung cancer patients. There are two types of PBT - a passively scattered approach and a scanning approach. Typically, a passively scattered approach is more robust for respiratory movement and a scanning approach could result in a more conformal dose distribution even when the tumor shape is complex. Large tumors of centrally located lung cancer may be more suitably irradiated than with intensity-modulated radiotherapy (IMRT) or stereotactic body radiotherapy (SBRT). For a locally advanced lung cancer, PBT can spare the lung and heart more than photon IMRT. However, no randomized controlled trial has reported differences between PBT and IMRT or SBRT for early-stage and locally advanced lung cancers. Therefore, a well-designed controlled trial is warranted.

Special topics in immunotherapy and radiation therapy: reirradiation and palliation

Immunotherapy has revolutionized the treatment of non-small cell lung cancer (NSCLC). However, thus far, its use has only been established in patients with advanced disease either as first-line therapy in selected patients or following chemotherapy. What is not yet known is how best to incorporate radiation with immunotherapy agents. Many patients with advanced disease can benefit from palliative radiation, but the combination of radiation with immunotherapy has the potential to increase the toxicity of both modalities. Intriguingly, the combination also has the potential to enhance the efficacy of both modalities. For this reason, combining immunotherapy and radiation may help salvage patients with recurrent localized disease who are candidates for re-irradiation. We review the current data evaluating immunotherapy with both palliative radiation as well as definitive re-irradiation in NSCLC.