Advances in radiotherapy techniques and delivery for non-small cell lung cancer: benefits of intensity-modulated radiation therapy, proton therapy, and stereotactic body radiation therapy

IMRT in the treatment of locally advanced or inoperable NSCLC in the pre-durvalumab era: clinical outcomes and pattern of relapses, experience from the Oscar Lambret Center

Background

Intensity-modulated conformal radiotherapy (IMRT) has become the technique of choice for the treatment of locally advanced or inoperable non-small cell lung cancer (NSCLC). Nevertheless, this technique presents dosimetric uncertainties, particularly in treating moving targets such as pulmonary neoplasms. Moreover, it theoretically increases the risk of isolated nodal failure (INF) due to reduced incidental irradiation.

Objective

The objective of this study was to evaluate the efficacy and safety of IMRT in patients with inoperable NSCLC and to describe the pattern of relapses.

Methods

Patients with locally advanced NSCLC treated with radiotherapy and chemotherapy between 2015 and 2018 at the Oscar Lambret Center were retrospectively included in the study. Overall and progression-free survival were estimated using the Kaplan-Meier method. The cumulative incidence of the different components of relapse was estimated using the Kalbfleisch and Prentice method. Prognostic factors for relapse/death were investigated using the Cox model. A comparison with literature data was performed using a one-sample log-rank test.

Results

Seventy patients were included, and 65 patients (93%) had stage III disease. All the patients received chemotherapy, most frequently with cisplatin and navelbine. The dose received was 66 Gy administered in 33 fractions. The median follow-up and survival were 49.1 and 39.1 months, respectively. A total of 35 deaths and 43 relapses, including 29 with metastatic components, were reported. The overall survival rates at 1 and 2 years were 80.2% (95% confidence interval 68.3%-88.0%) and 67.2% (95% confidence interval 54.2%-77.3%), respectively. Locoregional relapse was observed in 14 patients, including two INF, one of which was located in the lymph node area adjacent to the clinical target volume. Median relapse-free survival was 15.2 months. No variable was statistically associated with the risk of relapse/death in multivariate analysis. Seven patients (10%) experienced grade 3 or higher toxicity.

Conclusion

The use of IMRT for locally advanced or inoperable NSCLC led to favorable long-term clinical outcomes. The rate of locoregional relapse, particularly isolated lymph node failure, was low and comparable with that of the three-dimensional radiotherapy series, as was the rate of early and late toxicities.

Effects of Chinese herbal diet on hematopoiesis, immunity, and intestines of mice exposed to different doses of radiation

Radiotherapy causes a series of side effects in patients with malignant tumors. Polygonati Rhizoma, Achyranthis Bidentatae Radix, and Epimedii Folium are all traditional Chinese herbs with varieties of functions such as anti-radiation and immune regulation. In this study, the above three herbs were used as a herbal diet to study their effects on the hematopoietic, immune, and intestinal systems of mice exposed to three doses of radiation. Our study showed that the diet had no radiation-protective effect on the hematopoietic and immune systems. However, at the radiation dose of 4 Gy and 8 Gy, the diet showed an obvious radiation-protective effect on intestinal crypts. At the dose of 8 Gy, we also found that the Chinese herbal diet had an anti-radiation effect on reducing the loss of the inhibitory nNOS⁺ neurons in the intestine. That provides a new diet for relieving the symptoms of hyperperistalsis and diarrhea in patients after radiotherapy.

Patients with Lower Positive Lymph Nodes Ratio May Benefit from Preoperative Radiotherapy in Stage III Non-Small Cell Lung Cancer

BACKGROUND

Although preoperative radiotherapy (PORT) is a promising therapeutic option for stage III non-small cell lung cancer (NSCLC), the efficacy of this treatment remains controversial. The positive lymph node ratio (PLNR) is recognized as an independent prognostic factor for survival. However, no previous studies have focused on the association between PLNR and PORT in stage III NSCLC.

METHODS

Data were collected from the Surveillance, Epidemiology and End Results (SEER) database, and all patients enrolled in this analysis were diagnosed during 2010-2015. The primary endpoint was overall survival (OS). Univariate and multivariate Cox regression analysis was used to identify factors associated with survival before and after case-control matching. PLNR was defined as the ratio of the number of positive lymph nodes to the total number of retrieved or examined lymph nodes. A cutoff value for PLNR was calculated using an X-tile model.

RESULTS

Overall, 391 patients with PORT and 2814 patients without PORT were enrolled in this study. The cohort after 1:1 case-control matching included 322 patients who received PORT and 322 patients without PORT. PORT was not associated with a significant effect on OS (HR  =  1.14; 95% CI: 0.91-1.43; P  =  0.825). Multivariate Cox regression analysis showed that PLNR (P < 0.001) was independently associated with OS in patients with stage III NSCLC. An X-tile model was used to identify a cutoff value for PLNR: the risk of death was significantly lower in patients with PLNR ≤0.41 who received PORT than in those with PLNR >0.41 who received PORT (HR  =  0.59; 95% CI: 0.38-0.91; P  =  0.015).

CONCLUSION

PLNR may be a prognostic factor for survival in patients with stage III NSCLC who undergo PORT. Lower PLNR is a predictor of better OS and thus warrants further study.

Relationship between Dose Prescription Methods and Local Control Rate in Stereotactic Body Radiotherapy for Early Stage Non-Small-Cell Lung Cancer: Systematic Review and Meta-Analysis

Variations in dose prescription methods in stereotactic body radiotherapy (SBRT) for early stage non-small-cell lung cancer (ES-NSCLC) make it difficult to properly compare the outcomes of published studies. We conducted a comprehensive search of the published literature to summarize the outcomes by discerning the relationship between local control (LC) and dose prescription sites. We systematically searched PubMed to identify observational studies reporting LC after SBRT for peripheral ES-NSCLC. The correlations between LC and four types of biologically effective doses (BED) were evaluated, which were calculated from nominal, central, and peripheral prescription points and, from those, the average BED. To evaluate information on SBRT for peripheral ES-NSCLC, 188 studies were analyzed. The number of relevant articles increased over time. The use of an inhomogeneity correction was mentioned in less than half of the articles, even among the most recent. To evaluate the relationship between the four BEDs and LC, 33 studies were analyzed. Univariate meta-regression revealed that only the central BED significantly correlated with the 3-year LC of SBRT for ES-NSCLC (p = 0.03). As a limitation, tumor volume, which might affect the results of this study, could not be considered due to a lack of data. In conclusion, the central dose prescription is appropriate for evaluating the correlation between the dose and LC of SBRT for ES-NSCLC. The standardization of SBRT dose prescriptions is desirable.

Clinically-meaningful improvements in therapy for unresectable NSCLC

INTRODUCTION

The ideal management of patients with unresectable non-small-cell lung cancer (NSCLC) is still developing. Unresectable NSCLC has a high mortality rate and poor prognosis, but the development of immune checkpoint inhibitors (ICIs) and molecular-targeted therapies has been a breakthrough in the treatment. The correct treatment of this patient population is crucial to maximize the clinical benefits without compromising their quality of life (QOL).

AREAS COVERED

We review the chemoradiotherapies, cytotoxic chemotherapies, immunotherapies, and molecular-targeted therapies available for unresectable NSCLC, focusing on their effects on overall survival, progression-free survival, and QOL.

EXPERT OPINION

Although cure is the ultimate goal of cancer treatment, it is often difficult to achieve in advanced NSCLC. Biomarker surveillance techniques, such as next-generation sequencing, have made it possible to provide the most appropriate treatment for each patient. This has led to clinically-meaningful improvements in therapies for unresectable NSCLC. The development of new molecular-targeted therapies and the establishment of treatment for patients who acquired drug resistance after initial treatment have a positive impact on patients' long-term survival. ICIs lead the long-term survival that can be considered a cure of some patients with advanced NSCLC, but such curative survival is difficult to achieve with cytotoxic chemotherapies and molecular-targeted therapies.

Redefine the Role of Proton Beam Therapy for the Locally-Advanced Non-Small Cell Lung Cancer Assisting the Reduction of Acute Hematologic Toxicity

Purpose

To investigate the potential clinical benefit of utilizing intensity-modulated proton therapy (IMPT) to reduce acute hematologic toxicity for locally advanced non-small cell lung cancer (LA-NSCLC) patients and explore the feasibility of a model-based patient selection approach via the normal tissue complication probability (NTCP).

Methods

Twenty patients with LA-NSCLC were retrospectively selected. Volumetric modulated arc photon therapy (VMAT) and IMPT plans were generated with a prescription dose of 60 Gy in 30 fractions. A wide range of cases with varied tumor size, location, stations of metastatic lymph nodes were selected to represent the general cancer group. Contouring and treatment planning followed RTOG-1308 protocol. Doses to thoracic vertebral bodies (TVB) and other organ at risks were compared. Risk of grade ≥ 3 acute hematologic toxicity (HT3+) were calculated based on the NTCP model, and patients with a reduction on NTCP of HT3+ from VMAT to IMPT (△NTCP_HT3+) ≥ 10% were considered to ‘significantly benefit from proton therapy.’

Results

Compared to VMAT, IMPT significantly reduced the dose to the TVB, the lung, the heart, the esophagus and the spinal cord. Tumor distance to TVB was significantly associated with △NTCP _HT3+ ≥ 10%. For the patients with tumor distance ≤ 0.7 cm to TVB, the absolute reduction of dose (mean, V30 and V40) to TVB was significantly lower than that in patients with tumor distance &gt; 0.7 cm.

Conclusion

IMPT decreased the probability of HT3+ compared to VMAT by reducing the dose to the TVB in LA-NSCLC patients. Patients with tumor distance to TVB less than 0.7 cm are likely to benefit most from proton over photon therapy.

Impact of Introducing Intensity Modulated Radiotherapy on Curative Intent Radiotherapy and Survival for Lung Cancer

Background

Lung cancer survival remains poor. The introduction of Intensity-Modulated Radiotherapy (IMRT) allows treatment of more complex tumours as it improves conformity around the tumour and greater normal tissue sparing. However, there is limited evidence assessing the clinical impact of IMRT. In this study, we evaluated whether the introduction of IMRT had an influence on the proportion of patients treated with curative-intent radiotherapy over time, and whether this had an effect on patient survival.

Materials and Methods

Patients treated with thoracic radiotherapy at our institute between 2005 and 2020 were retrospectively identified and grouped into three time periods: A) 2005-2008 (pre-IMRT), B) 2009-2012 (selective use of IMRT), and C) 2013-2020 (full access to IMRT). Data on performance status (PS), stage, age, gross tumour volume (GTV), planning target volume (PTV) and survival were collected. The proportion of patients treated with a curative dose between these periods was compared. Multivariable survival models were fitted to evaluate the hazard for patients treated in each time period, adjusting for PS, stage, age and tumour volume.

Results

12,499 patients were included in the analysis (n=2675 (A), n=3127 (B), and n=6697 (C)). The proportion of patients treated with curative-intent radiotherapy increased between the 3 time periods, from 38.1% to 50.2% to 65.6% (p<0.001). When stage IV patients were excluded, this increased to 40.1% to 58.1% to 82.9% (p<0.001). This trend was seen across all PS and stages. The GTV size increased across the time periods and PTV size decreased. Patients treated with curative-intent during period C had a survival improvement compared to time period A when adjusting for clinical variables (HR=0.725 (0.632-0.831), p<0.001).

Conclusion

IMRT was associated with to more patients receiving curative-intent radiotherapy. In addition, it facilitated the treatment of larger tumours that historically would have been treated palliatively. Despite treating larger, more complex tumours with curative-intent, a survival benefit was seen for patients treated when full access to IMRT was available (2013-2020). This study highlights the impact of IMRT on thoracic oncology practice, accepting that improved survival may also be attributed to a number of other contributing factors, including improvements in staging, other technological radiotherapy advances and changes to systemic treatment.

Treatment Patterns for Patients With Unresected Stage III NSCLC: Analysis of the Surveillance, Epidemiology, and End Results (SEER) Database

Background

Recently, immunotherapy (IO) has shown striking survival improvement in unresectable stage III non-small cell lung cancer (NSCLC). However, the role of chemo-radiotherapy (CRT) for improvement in outcomes should not be disregarded. This study aimed to compare the treatment patterns and illustrate the impact of radiotherapy on the cancer-specific survival (CSS) and overall survival (OS) of patients with unresected locally advanced stage III NSCLC.

Methods

We retrospectively analyzed the data of patients with stage III NSCLC patients who did not undergo surgery from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database between 2001 and 2016, and three continuous years were regarded as one unit. Using the Kaplan-Meier method, we identified the CSS and OS. Then, a linear regression model was graphed to analyze the correlation between median survival of CSS or OS and calendar years in the radiotherapy alone, chemotherapy alone, and CRT groups.

Results

A total of 20986 patients were included in this study. In the overall cohort, CSS and OS improved consistently. To explore the reason for the improved survival, patients were divided into three different cohorts: radiotherapy alone, chemotherapy alone, and CRT. From 2001 to 2015, the median CSS improved persistently, 7, 8, 8, 9, and 11 months in the radiotherapy alone group and 12, 13, 15, 17, 19 months in the CRT group, but improvement in outcomes was less consistent in the chemotherapy alone group (10, 9, 11, 12, 12 months). To better visualize the correlation between CSS and calendar year, linear regression was performed, yielding r2 = 0.8032, P = 0.0395 for the radiotherapy alone group; r2 = 0.7206, P = 0.0689 for the chemotherapy alone group; and r2 = 0.9878, P = 0.0006 for the CRT group. Similar findings were observed in the OS data. In addition to this, we also analyzed different pathological types and also obtained the same results.

Conclusions

The survival of patients with unresectable stage III NSCLC has improved substantially, and the most pronounced and consistent improvements were observed in the CRT group. In addition to IO, radiotherapy played an essential role in the treatment of unresectable stage III NSCLC in the past years and should be considered in the design of clinical trials.

Vulnerabilities of radiomic features to respiratory motion on four-dimensional computed tomography-based average intensity projection images: A phantom study

PURPOSE

To evaluate the influence of respiratory motion on the robustness of radiomic features on four-dimensional computed tomography (4DCT)-based average intensity projection (AIP) images by employing an anthropomorphic chest phantom.

METHODS

Three spherical objects (φ30 mm), namely, acrylic (100 Hounsfield unit [HU], homogeneous), rubber (-140 HU, homogeneous), and cork (-630 HU, heterogeneous), were moved with motion amplitudes of 0, 1, 2.5, 4, 6, 8, and 10 mm in the phantom, and 4DCT scans were repeated at four different locations. Thereafter, the AIP images were generated considering the average of the 10 respiratory phases of the 4DCT images. Further, the targets were manually delineated on the AIP images in the lung window setting. A total of 851 radiomic features, including 107 unfiltered features and 744 wavelet filter-based features, were extracted from the region of interest for each material. The feature robustness among the different target motion amplitude (ε) was evaluated by normalizing the feature variability of the target motion relative to the variability of data from 573 patients with early-stage non-small cell lung cancer. The features with absolute ε values ≤0.5 were considered highly robust to target motions.

RESULTS

The percentage of robust unfiltered and wavelet filter-based features with a motion amplitude of 1 mm was greater than 83.2% and 93.4%, respectively; however, the percentage decreased by more than 24.3% and 17.6%, respectively, for motion amplitudes greater than 2.5 mm. The movement of cork had a small effect on the feature robustness compared to that of acrylic and rubber, regardless of the target motion amplitudes.

CONCLUSIONS

Our phantom study demonstrated that target motion amplitudes ≤1 mm led to the robustness of radiomic features on the 4DCT-based AIP images of thoracic regions. The frequency components and directions of the wavelet filters may be essential factors in 4DCT-based radiomic analysis.

Update of Incidence, Prevalence, Survival, and Initial Treatment in Patients With Non-Small Cell Lung Cancer in the US

Importance

Updated estimates of non-small cell lung cancer (NSCLC) in the US are needed.

Objective

To calculate the most recent epidemiologic estimates of NSCLC in the US.

Design, Setting, and Participants

This cross-sectional epidemiological analysis used the most recently released data from US cancer registries. The population-based US Cancer Statistics (USCS) database (2010-2017), comprised of the Surveillance, Epidemiology, and End Results (SEER) program and the National Program of Cancer Registries (NPCR) (collectively, SEER-NPCR) provided the NSCLC incidence estimate. The SEER-18 database provided data for incidence, prevalence, survival, and initial treatment by NSCLC stage. Adults aged 18 years or older diagnosed with NSCLC identified by International Classification of Diseases for Oncology, Third Edition, morphology codes were included.

Main Outcomes and Measures

Annual age-adjusted NSCLC incidence per 100 000 persons; annual prevalence per 100 000 persons; survival rate; initial treatment. Due to database release delays, incidence data were available through 2017, and other parameters through 2016. The analysis was conducted from June 2020 to July 2020.

Results

There were 1.28 million new NSCLC cases recorded during 2010 to 2017 in the US (SEER-NPCR: 53% male; 67% ≥ 65 years). From 2010 to 2017, NSCLC incidence per 100 000 decreased from 46.4 to 40.9 overall (age <65 years: 15.5 to 13.5; age ≥65 years: 259.9 to 230.0); the incidence of stage II, IIIA, and IIIB NSCLC was stable, and stage IV decreased slightly from 21.7 to 19.6, whereas stage I incidence increased from 10.8 to 13.2. From 2010 to 2016, NSCLC prevalence per 100 000 increased from 175.3 to 198.3 (nationwide projection of SEER-18); prevalence increased among younger patients (77.5 to 87.9) but decreased among older patients (825.1 to 812.4). Period survival analysis found that 26.4% of patients survived 5 years, which is higher than previously reported. The proportion of stage I NSCLC treated with radiation as single initial treatment rose markedly from 14.7% in 2010 to 25.7% in 2016. Patients with stage IV NSCLC aged 65 years or older were most likely to be untreated (38.3%).

Conclusions and Relevance

The findings of this cross-sectional epidemiological analysis suggest that the increased incidence of stage I NSCLC at diagnosis likely reflected improved evaluation of incidental nodules. A smaller proportion of patients aged 65 years or older with stage IV NSCLC were treated. Earlier detection and availability of effective treatments may underlie increased overall NSCLC prevalence, and higher than previously reported survival.

Predicting personalised optimal arc parameter using knowledge-based planning model for inoperable locally advanced lung cancer patients to reduce organ at risk doses

Objectives. Volumetric modulated arc therapy (VMAT) allows for reduction of organs at risk (OAR) volumes receiving higher doses, but increases OAR volumes receiving lower radiation doses and can subsequently increasing associated toxicity. Therefore, reduction of this low-dose-bath is crucial. This study investigates personalizing the optimization of VMAT arc parameters (gantry start and stop angles) to decrease OAR doses.Materials and Methods. Twenty previously treated locally advanced non-small cell lung cancer (NSCLC) patients treated with half-arcs were randomly selected from our database. These plans were re-optimized with seven different arcs parameters; optimization objectives were kept constant for all plans. All resulting plans were reviewed by two clinicians and the optimal plan (lowest OAR doses and adequate target coverage) was selected. Furthermore, knowledge-based planning (KBP) model was developed using these plans as 'training data' to predict optimal arc parameters for individual patients based on their anatomy. Treatment plan complexity scores and deliverability measurements were performed for both optimal and original clinical plans.Results.The results show that different arc geometries resulted in different dose distributions to the OAR but target coverage was mostly similar. Different arc geometries were required for different patients to minimize OAR doses. Comparison of the personalized against the standard (2 half-arcs) plans showed a significant reduction in lung V₅(lung volume receiving 5 Gy), mean lung dose and mean heart doses. Reduction in lung V₂₀and heart V₃₀were statistically insignificant. Plan complexity and deliverability measurements show the test plans can be delivered as planned.Conclusions.Our study demonstrated that personalizing arc parameters based on an individual patient's anatomy significantly reduces both lung and heart doses. Dose reduction is expected to reduce toxicity and improve the quality of life for these patients.

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.

Effect of Intensity Modulated Radiotherapy (IMRT) on the immunity, physical status and clinical effect of locally advanced NSCLC patients

Objectives:

To evaluate the clinical value of radiotherapy combined with Camrelizumab in treating locally advanced non-small cell lung cancer (NSCLC) patients.

Methods:

80 locally advanced NSCLC patients were randomly divided into two groups (n=40). The control group was administered with intensity modulated radiation therapy (IMRT), whereas the experimental group with Camrelizumab in addition to IMRT. All the patients underwent clinical efficacy evaluation in terms of adverse drug reaction (ADR), physical status improvement after the treatment, and changes in T lymphocyte subpopulations (incl. CD3⁺, CD4⁺, CD8⁺, CD4⁺/CD8⁺).

Results:

The efficacy was found to be 70% and 47.5 in experimental group and control group, respectively, with the former being significantly better than the latter (p=0.03). The ADR rates were 50% and 37.5% in the experimental group and control group, respectively; but the difference remained insignificant (p=0.26). As for physical status improvement, experimental group evidently excelled the control group (p=0.04). The post-treatment indicators such as CD3⁺, CD4⁺, CD8⁺, CD4⁺/CD8⁺ were significantly more improved in the experimental group than the control group (CD3⁺, p=0.02; CD4⁺, p=0.00; and CD4⁺/CD8⁺, p=0.01). However, the changes in CD8+ were not significant at all (p=0.46).

Conclusions:

The combined therapy of IMRT with Camrelizumab appeared effective in dealing with the locally advanced NSCLC patients, as such patients presented significantly better immune state and physical status improvement but not increased ADR. The therapy is both safe and effective.

Dosimetric impact of positron emission tomography-based gross tumour volume (GTV) delineation over conventional CT-based GTV delineation for carcinoma oesophagus

Aim:

The aim of the study was to find the dosimetric impact of positron emission tomography (PET)-based gross tumour volume (GTV) delineation over computed tomography (CT)-based GTV delineation for carcinoma oesophagus.

Methods:

Fifteen patients with carcinoma oesophagus were retrospectively selected. Two sets of GTVs in CT plain images were generated, one with the help of intravenous and oral contrast (GTV CT) and the other with only using PET uptake with the standardised uptake value (simple way of determining the activity in PET) (SUV) > 2.5 (GTV PET). Corresponding PTVs were generated. For all patients, rapid arc plans were generated. Changes in target volumes and critical structure doses were evaluated. The Wilcoxon signed-rank test was used for statistical analysis, and p value < 0.05 was assumed as statistically significant.

Results:

Mean reduction in GTV was 5.76 ± 19.35 cc. Mean reduction in PTV 45 Gy was 42.40 ± 76.39 cc. Mean reduction in heart mean dose was 1.53 ± 2.16 Gy. Mean reductions in left lung V20% and V10% were 2.43 ± 4.28 and 3.25 ± 5.09 Gy, respectively. Mean reductions in right lung V20% and V10% were 3.11 ± 4.91 and 2.80 ± 4.51 Gy, respectively. Mean reduction in total lung mean dose was 1.00 ± 1.19 Gy.

Finding:

PET-based GTV contouring reduces the treatment volume and critical structure doses significantly over CT-based GTV contouring for carcinoma oesophagus.

Second Malignancies after Radiation Therapy: Update on Pathogenesis and Cross-sectional Imaging Findings

A wide spectrum of second cancers occur as late complications of radiation therapy (RT) used to treat various malignancies. In addition to the type and dose of radiation, lifestyle, environmental, and genetic factors are important to the development of second malignancies in cancer survivors. Typically, RT-induced malignancies (RTIMs) are biologically aggressive cancers with a variable period of 5-10 years for hematologic malignancies and 10-60 years for solid tumors between RT and the development of the second cancer. Although carcinomas and leukemias commonly develop after low-dose RT, sarcomas occur in tissues or organs that receive high-dose RT. Angiosarcomas and unclassified pleomorphic sarcomas are the two most common RT-associated sarcomas; other sarcomas include malignant peripheral nerve sheath tumors, leiomyosarcomas, osteosarcomas, chondrosarcomas, and dedifferentiated or pleomorphic liposarcomas. Select RTIMs show tumor genetic characteristics that allow accurate diagnosis. Nearly all cutaneous angiosarcomas after RT for breast cancer and 90% of RT-associated malignant peripheral nerve sheath tumors are characterized by MYC gene amplifications and loss of H3 K27me3 expression, respectively. Classic papillary thyroid carcinomas that develop after RT frequently harbor RET/PTC rearrangements and have a favorable prognosis, despite their advanced stage at patient presentation. Select RTIMs demonstrate characteristic imaging findings and typically develop in the prior radiation field. Imaging is essential to early diagnosis, characterization, localization, and staging of RTIMs. Familiarity of radiologists with the diverse spectrum of RTIMs is essential for early diagnosis and optimal management. An invited commentary by Shapiro is available online. ^©RSNA, 2021.

A systematic review and meta-analysis of treatment-related toxicities of curative and palliative radiation therapy in non-small cell lung cancer

Treatment-related toxicity is an important component in non-small cell lung cancer (NSCLC) management decision-making. Our aim was to evaluate and compare the toxicity rates of curative and palliative radiotherapy with and without chemotherapy. This meta-analysis provides better quantitative estimates of the toxicities compared to individual trials. A systematic review of randomised trials with > 50 unresectable NSCLC patients, treated with curative or palliative conventional radiotherapy (RT) with or without chemotherapy. Data was extracted for oesophagitis, pneumonitis, cardiac events, pulmonary fibrosis, myelopathy and neutropenia by any grade, grade ≥ 3 and treatment-related deaths. Mantel–Haenszel fixed-effect method was used to obtain pooled risk ratio. Forty-nine trials with 8609 evaluable patients were included. There was significantly less grade ≥ 3 acute oesophagitis (6.4 vs 22.2%, p < 0.0001) and any grade oesophagitis (70.4 vs 79.0%, p = 0.04) for sequential CRT compared to concurrent CRT, with no difference in pneumonitis (grade ≥ 3 or any grade), neutropenia (grade ≥ 3), cardiac events (grade ≥ 3) or treatment-related deaths. Although the rate of toxicity increased with intensification of treatment with RT, the only significant difference between treatment regimens was the rate of oesophagitis between the use of concurrent and sequential CRT. This can aid clinicians in radiotherapy decision making for NSCLC.

Radiation Modalities Used in Lung Cancer: An Overview for Thoracic Surgeons

Radiation is a constantly evolving technology which plays a role in the management of lung cancer in a variety of settings: as an adjunct to surgery, definitively, and palliatively. Key aspects of radiation oncology-including acute and chronic toxicities of thoracic radiation and rationale for choosing one modality of radiation over another-may be obscure to those outside the field. We aim to provide a useful overview relevant for the thoracic surgeon of radiation technology and delivery. A review was performed of salient articles identifying radiation technologies used in lung cancer which were summarized and expounded upon with focus on integrating their history, evolution, and landmark trials establishing basis of their use. This article reviews the four fundamental means of external beam radiation employed in managing lung cancer and provides visual examples of comparison plans. We also touch on potential practice-changing developments in regards to proton therapy and radiation in the era of immunotherapy. Radiation oncology has evolved considerably over time to become a critical part of lung cancer management, particularly in early-stage inoperable disease and locally advanced disease. Maximizing tumor control while minimizing toxicity drives treatment strategies. Knowledge of these fundamentals will help the thoracic surgeon answer many questions patients pose regarding radiation.

Effects of glutamine for prevention of radiation-induced esophagitis: a double-blind placebo-controlled trial

Purpose Acute radiation-induced esophagitis (ARIE) leads to treatment delays, decreased quality of life (QOL), and secondary adverse events such as weight loss. Grade 3 ARIE occurs in 15%-30% of patients undergoing radiotherapy to the esophagus, leading to disruption or discontinuation of treatment. The purpose of this study was to assess the effects of glutamine, a common nutritional supplement, on ARIE in patients with thoracic malignancies. Patients and methods This double-blind, placebo-controlled trial enrolled patients with advanced thoracic malignancies receiving concurrent chemotherapy/radiotherapy or radiotherapy alone, with radiation doses to the esophagus ≥45 Gy. Patients were randomized (1:1) to receive 4 g of glutamine or glycine placebo twice daily. The primary objective was to determine whether glutamine decreases the severity of ARIE in these patients. Secondary objectives included assessment of the effects of glutamine on other measures of ARIE, weight, symptom burden measure assessed by the MD Anderson Symptom Inventory (MDASI-HN) questionnaire and the toxicity profile of glutamine. Results At the time of interim analysis, 53 patients were enrolled: 27 in the glutamine arm and 26 in the placebo arm. There was no difference in the incidence of esophagitis in the first 6 weeks of radiotherapy between the glutamine and placebo arms (74% versus 68%; P = 1.00). There were no significant differences between the two arms for time to onset of esophagitis. The duration of ARIE was shorter (6.3 versus 7.1 weeks; P = 0.54) and median weight loss was lower (0.9 kg versus 2.8 kg; p = 0.83) in the glutamine arm versus the placebo arm. The groups differ significantly in core symptom severity (2.1 vs 1.5, p < .03) but not in head and neck specific symptom severity (1.2 vs 1.1, p < .60) nor in symptom interference (2.1 vs 1.7, p < .22). There was no grade 3 or higher adverse event at least possibly related to glutamine. The study was terminated for futility following interim analysis. Conclusion Oral glutamine was not associated with significant improvement in severity of ARIE, weight loss, head and neck specific symptoms or symptom interference compared with placebo in patients with advanced thoracic malignancies receiving radiotherapy to the esophagus.Clinical trial information. NCT01952847, and date of registration is September 30, 2013.

Feasibility of MR-guided radiotherapy using beam-eye-view 2D-cine with tumor-volume projection

PURPOSE

Current magnetic resonance imaging (MRI) guided radiotherapy (MRgRT) applies sagittal/coronal 2D-cine to monitor major tumor motions, however, the beam eye's view (BEV) with volumetric tumor projection would be the best measure for radiation beam conformality, independent of tumor through-plane motion. The goal is to assess the feasibility, accuracy, and performance of the BEV approach.

METHODS

Beam-specific BEV 2D-cine with volume-projected tumor contours were simulated to establish a 2D/3D tumor match against a tumor-motion library based on multi-breath time-resolved (TR) 4DMRI images. Two BEV-library-matching methods were developed: (1) fast screening with tumor center-of-mass (∆COM), in-plane area ratio, and DICE similarity, and finalizing with the highest DICE score and (2) DICE screening for top-3 candidates and finalizing with rigid registration. A 4D-XCAT digital phantom and 8 lung-cancer patients were used for assessment. For each patient, 3 sets of 40 s TR-4DMRI were acquired at 2 Hz and 6 representative BEV were created with the isocenter set at tumor COM in mid-respiration. One TR-4DMRI set (40 × 2 = 80-images) was used to simulate BEV 2D-cine and the other two (160-images) were used to create a library. The matching result was validated against the ground truth within the test set. Using a leave-one-out strategy, the success rate, accuracy, and speed of tumor matching were assessed for volume-projected tumors over 11520 time-points (=8patients•3sets•80images•6BEVs).

RESULTS

Volume-projected tumor contour area on the 6 BEVs varies by 60% ± 8% and [Formula: see text] (in-plane/volume-projected) varies by 82% ± 9%. The [Formula: see text] changes with tumor shape, orientation, and through-plane motion. Method-1 produces 96% matching success (ΔCOM = 0.7 ± 0.2 mm, [Formula: see text]=1.01 ± 0.02, Dice=0.92 ± 0.02) with the computational time of 15 ± 1 ms/match, while method-2 produces 94% ± 1% success (ΔCOM = 0.2 ± 0.1 mm, [Formula: see text]=1.00 ± 0.01, Dice = 0.94 ± 0.02) with 223 ± 13 ms/match.

CONCLUSION

This study has demonstrated the feasibility, accuracy, and benefits of BEV 2D-cine imaging with tumor-volume projection, allowing real-time tumor motion monitoring and beam conformality checking. Further clinical evaluation is necessary before MRgRT applications.

Proton therapy for thoracic malignancies: a review of oncologic outcomes

Introduction: Radiotherapy is an integral component in the treatment of the majority of thoracic malignancies. By taking advantage of the steep dose fall-off characteristic of protons combined with modern optimization and delivery techniques, proton beam therapy (PBT) has emerged as a potential tool to improve oncologic outcomes while reducing toxicities from treatment.Areas covered: We review the physical properties and treatment techniques that form the basis of PBT as applicable for thoracic malignancies, including a brief discussion on the recent advances that show promise to enhance treatment planning and delivery. The dosimetric advantages and clinical outcomes of PBT are critically reviewed for each of the major thoracic malignancies, including lung cancer, esophageal cancer, mesothelioma, thymic cancer, and primary mediastinal lymphoma.Expert opinion: Despite clear dosimetric benefits with PBT in thoracic radiotherapy, the improvement in clinical outcomes remains to be seen. Nevertheless, with the incorporation of newer techniques, PBT remains a promising modality and ongoing randomized studies will clarify its role to determine which patients with thoracic malignancies receive the most benefit. Re-irradiation, advanced disease requiring high cardio-pulmonary irradiation volume and younger patients will likely derive maximum benefit with modern PBT.

Evaluation of continuous beam rescanning versus pulsed beam in pencil beam scanned proton therapy for lung tumours

The treatment of moving targets with pencil beam scanned proton therapy (PBS-PT) may rely on rescanning strategies to smooth out motion induced dosimetric disturbances. PBS-PT machines, such as Proteus®Plus (PPlus) and Proteus®One (POne), deliver a continuous or a pulsed beam, respectively. In PPlus, scaled (or no) rescanning can be applied, while POne implies intrinsic 'rescanning' due to its pulsed delivery. We investigated the efficacy of these PBS-PT delivery types for the treatment of lung tumours. In general, clinically acceptable plans were achieved, and PPlus and POne showed similar effectiveness.

The Therapeutic Potential of DNA Damage Repair Pathways and Genomic Stability in Lung Cancer

Despite advances in our understanding of the molecular biology of the disease and improved therapeutics, lung cancer remains the most common cause of cancer-related deaths worldwide. Therefore, an unmet need remains for improved treatments, especially in advanced stage disease. Genomic instability is a universal hallmark of all cancers. Many of the most commonly prescribed chemotherapeutics, including platinum-based compounds such as cisplatin, target the characteristic genomic instability of tumors by directly damaging the DNA. Chemotherapies are designed to selectively target rapidly dividing cells, where they cause critical DNA damage and subsequent cell death (1, 2). Despite the initial efficacy of these drugs, the development of chemotherapy resistant tumors remains the primary concern for treatment of all lung cancer patients. The correct functioning of the DNA damage repair machinery is essential to ensure the maintenance of normal cycling cells. Dysregulation of these pathways promotes the accumulation of mutations which increase the potential of malignancy. Following the development of the initial malignancy, the continued disruption of the DNA repair machinery may result in the further progression of metastatic disease. Lung cancer is recognized as one of the most genomically unstable cancers (3). In this review, we present an overview of the DNA damage repair pathways and their contributions to lung cancer disease occurrence and progression. We conclude with an overview of current targeted lung cancer treatments and their evolution toward combination therapies, including chemotherapy with immunotherapies and antibody-drug conjugates and the mechanisms by which they target DNA damage repair pathways.

Augmenting the therapeutic window of radiotherapy: A perspective on molecularly targeted therapies and nanomaterials

Radiation therapy is a cornerstone of modern cancer therapy alongside surgery, chemotherapy, and immunotherapy, with over half of all cancer patients receiving radiation therapy as part of their treatment regimen. Development of novel radiation sensitizers that can improve the therapeutic window of radiation therapy are sought after, particularly for tumors at an elevated risk of local and regional recurrence such as locally-advanced lung, head and neck, and gastrointestinal tumors. This review discusses clinical strategies to enhance radiotherapy efficacy and decrease toxicity, hence, increasing the overall therapeutic window. A focus is given to the molecular targets that have been identified and their associated mechanisms of action in enhancing radiotherapy. Examples include cell survival and proliferation signaling such as the EGFR and PI3K/AKT/mTOR pathways, DNA repair genes including PARP and ATM/ATR, angiogenic growth factors, epigenetic regulators, and immune checkpoint proteins. By manipulating various mechanisms of tumor resistance to ionizing radiation (IR), targeted therapies hold significant value to increase the therapeutic window of radiotherapy. Further, the use of novel nanoparticles to enhance radiotherapy is also reviewed, including nanoparticle delivery of chemotherapies, metallic (high-Z) nanoparticles, and nanoparticle delivery of targeted therapies - all of which may improve the therapeutic window of radiotherapy by enhancing the tumor response to IR or reducing normal tissue toxicity.

Treatment time to the end of thoracic radiotherapy has more predictive power for survival than radiation dose intensity in patients with limited-stage small-cell lung cancer receiving concurrent chemoradiation of more than 45 Gy

The optimal protocol for thoracic radiotherapy (TRT) in combination with chemotherapy in patients with limited-stage small-cell lung cancer (LS-SCLC) remains elusive. The present study aimed to evaluate radiation parameters in association with survival outcomes. A total of 101 patients with LS-SCLC who completed TRT at ≥45 Gy and concurrent chemotherapy were retrospectively reviewed. The median dose and duration of TRT were 50 Gy and 38 days, respectively. The median duration from the start of either therapy to the end of TRT (SER) was 60 days. The median survival for all patients was 26.9 months. The 3-year local control (LC), progression-free survival (PFS) and overall survival (OS) rates were 52.0, 29.5 and 37.6%, respectively, and the 5-year LC, PFS and OS rates were 50.1, 28.3 and 26.7%, respectively. Univariate analysis revealed that patient age, tumor stage, timing and dose of TRT, SER, prophylactic cranial irradiation (PCI), and tumor response were significantly associated with treatment outcomes. Multivariate analysis revealed that stage was the only significant prognostic factor for LC (P=0.011), PFS (P<0.001) and OS (P<0.001). Tumor response (P=0.014), PCI (P=0.007) and SER (P=0.005) were significant predictors of OS. OS was improved in patients who achieved complete response, and their SER was ≤70 days (P<0.001). Short treatment duration (SER ≤70 days) was a significant predictor of OS in patients with LS-SCLC who completed planned TRT at ≥45 Gy with concurrent chemoradiotherapy.

Flexible bronchoscopy-guided microwave ablation in peripheral porcine lung: a new minimally-invasive ablation

Background

Transbronchial lung biopsy is an important approach to diagnose peripheral lung cancer, but bronchoscopy based treatment options are limited and poorly studied. A flexible bronchoscopy-guided water-cooled microwave ablation (MWA) catheter was developed to evaluate the feasibility and safety both in ex vivo and in vivo porcine models.

Methods

Using direct penetration of the catheter through the surface of ex vivo porcine lung, ablations (n=9) were performed at 70, 80, 90 W for 10 minutes. Temperatures of the catheter and 10, 15, 20 mm away from the tip were measured. Under bronchoscopy conditions in porcine lung, ablations (n=18, 6 in ex vivo and 12 in vivo) were performed at 80 W for 5 minutes. Computed tomography (CT) was acquired perioperative, 24 hours, 2 weeks, and 4 weeks post ablation. Ablation zones were excised at 24 hours and 4 weeks respectively. Long-axis diameter (Dl) and short-axis diameter (Ds) were measured and tissues were sectioned for pathological examination.

Results

In-ex vivo lung, the temperature at 20 mm removed was over 60 °C at 80 W for 288±26 seconds. The ablations under bronchoscopic conditions were successful in-ex vivo and in vivo lung. No complications occurred during the procedures. Coagulation necrosis was visible at 24 hours, and repaired fibrous tissue was seen at 4 weeks.

Conclusions

The flexible bronchoscopy-guided water-cooled MWA is feasible and safe. This early animal data holds promise of MWA becoming a potential therapeutic tool for Peripheral Lung Cancers.

Dosimetric comparison of dose accumulation between rigid registration and deformation registration in intensity-modulated radiation therapy for large volume non-small cell lung cancer

Background

To evaluate the cumulative dose to the target volumes and organs at risk (OARs) after replanning during intensity-modulated radiation therapy (IMRT) for large volume non-small cell lung cancer (NSCLC) based on rigid registration and deformation registration technologies.

Methods

Thirty patients with large volume NSCLC who were treated with IMRT were selected, and two four-dimensional computed tomography (4DCT) scans were acquired before radiotherapy and after 20 fractions of radiotherapy. The initial treatment plan (Plan₁) based on the average density projection CT (CT_1-avg) of the first 4DCT images and the second treatment plan (Plan₂) based on CT_2-avg of the second 4DCT images were calculated. Then, the dose distributions of Plan₂ and Plan₁ were accumulated based on rigid and deformation registration technologies to obtain Plan_rig and Plan_def, respectively. Finally, the volume changes of the gross tumor volume (GTV) and OARs between the two CT scans, and the dose-volume parameters among Plan₁, Plan₂, Plan_rig and Plan_def were compared.

Results

Compared with those on the first CT, the mean GTV and heart volume on the second CT decreased by 44.2% and 5.5%, respectively, while the mean volumes of the ipsilateral lung, contralateral lung and total lung increased by 5.2%, 6.2% and 5.8%, respectively. The differences in the above volume parameters between the two CT scans were statistically significant (P<0.05). Compared with those in Plan₁, the D₉₅, D₉₈ and V_100% values of the IGTV (GTV fusion of 10 CT phases) and planning target volume (PTV) in Plan₂ did not change significantly (P>0.05), and those of Plan_rig and Plan_def decreased slightly (P<0.05). The dose-volume parameters of the spinal cord, heart, ipsilateral lung and total lung in Plan₂, Plan_rig and Plan_def were significantly lower than those in Plan₁ (P<0.05). Among these parameters, V₃₀ and the mean dose to the heart in Plan₂, Plan_rig and Plan_def decreased by 27.3%, 16.5%, and 15.3% and 15.2%, 6.6%, and 5.6% compared to those in Plan₁, respectively; V₂₀ and the mean dose to the total lung in Plan₂, Plan_rig and Plan_def decreased by 15.6%, 4.5%, and 3.7% and 15.7%, 6.2%, and 5.1% compared to those in Plan₁, respectively. Some dose-volume parameters (including D₉₅ and D₉₈ to the target volume, V₄₀ of the heart, V₂₀ and the mean dose to the ipsilateral lung and the total lung) of Plan_def were slightly higher than those in Plan_rig (P<0.05). The Dice similarity coefficients (DSCs) of the OARs after deformation registration were significantly higher than those after rigid registration (P<0.05).

Conclusions

The dose-volume parameters of OARs in Plan₂ were noticeably different from those in Plan₁, so all of these parameters have large deviations in evaluating the actual dose to the OARs. And, the dose-volume parameters obtained by deformation registration can better predict the actual dose than those obtained by rigid registration.

Management of local recurrences and regional failure in early stage non-small cell lung cancer after stereotactic body radiation therapy

Stereotactic body radiation therapy (SBRT) is a very effective way to treat early stage non-small cell lung cancer (NSCLC) and small oligometastatic lung lesions with consistently high rates of local control, but both local and regional/distant recurrences still occur. The management of recurrences remains unsettled and may entail repeat SBRT, conventionally fractionated external beam RT (EF-EBRT), chemotherapy or surgery. Most patients with local recurrences [within the initial planning target volume (PTV)] can be salvaged successfully with good cancer specific survival. Nonetheless, proximity of the initial SBRT delivery to organs at risk (ribs, blood vessels, airways) may make retreatment more difficult. With attention to detail and careful patient selection, both surgery and reirradiation can be performed safely and effectively. Strategies for management of regional (nodal) recurrences may require conventional therapies tailored to the patterns of failure. The role of immunotherapy in salvage has not been elucidated as yet. We review here data on the available literature concerning salvage of SBRT lung patients.

SPECT V/Q in Lung Cancer Radiotherapy Planning

Curative-intent lung cancer radiation therapy either alone (RT) or combined with immuno-chemotherapy is associated with potential risk of serious radiation-induced lung injury. This review provides a summary of the role of SPECT ventilation perfusion (V/Q) imaging as an emerging adjunct to lung cancer RT planning and treatment dosimetry. Denoted "functional lung avoidance RT" it is hypothesized that preferential dosimetric avoidance of physiologically functional lung may reduce the frequency of radiation-induced lung injury. SPECT V/Q imaging datasets available during the planning process allows the prioritization (or "personalization') of RT dose to minimize the volume of functional lung probabilistically exposed to injurious radiation dose. Selective escalation of target dose and adaptive planning and replanning is also enabled. The emergent importance of the tumor-lung microenvironment and its biologic relationship to local immune effectors in lung cancer provides further incentive to individualize RT planning and delivery. This review examines important normal tissue dosimetric constraints that are part of current standards-of-care and the new dosimetric parameters associated with functional lung avoidance RT. SPECT V/Q has been a valuable tool in investigating the feasibility and efficacy of functional lung avoidance RT but is yet to become main stream due to the lack of large clinical trials. It is encouraging however that functional lung avoidance is feasible in RT dose-target delineation and some of the more promising studies are discussed.

Comparison of the effect of postoperative radiotherapy with surgery alone for esophagus squamous cell carcinoma patients: A meta-analysis

BACKGROUND

This meta-analysis was conducted to evaluate the effect of postoperative radiotherapy for patients having esophagus squamous cell carcinoma after radical surgery.

METHODS

A comprehensive research was performed in Pubmed, Embase and Cochrane Library electronic databases from inception until December 10, 2017. We collected all published full articles about comparison of surgery plus postoperative radiotherapy with surgery alone.

RESULTS

Four randomized-controlled trials (RCTs) with 1050 participants and 8 non-randomized-controlled trials with 3248 participants were included and evaluated separately. The risk ratio rate and its 95% confidence interval (CI) were calculated. Both RCTs and non-randomized-controlled trials (NRCTs) groups showed a significant increase in 3-year overall survival (OS) rate (RRRCT = 0.89, 95% CI: 0.80-0.99; RRNRCT = 0.82, 95% CI: 0.76-0.88) and decrease locoregional recurrence rate (RRRCT = 0.53, 95% CI: 0.43-0.66; RRNRCT = 0.47, 95% CI: 0.32-0.69) after postoperative radiotherapy compared with surgery alone. The 5-year OS rate in the group of NRCTs was markedly enhanced (RR = 0.87, 95% CI: 0.82-0.92), while that of the RCTs group was not enhanced in a significant way (RR = 0.84, 95% CI: 0.70-1.02). Subgroup analysis based on pathological lymph node status revealed that postoperative radiotherapy could improve OS regardless of pathological lymph node status (pathological lymph node positive patients: RR5-year os-RCT = 0.81, 95% CI: 0.70-0.93; RR5-year os-NRCT = 0.87, 95% CI: 0.80-0.94; Pathological lymph node negative patients: RR3-year os-RCT = 0.76, 95% CI: 0.59-0.96; RR3-year os-NRCT = 0.52, 95% CI: 0.30-0.89). No effect on distant recurrence rate was detected. Adverse effects induced by postoperative radiotherapy were comparatively modest and tolerable.

CONCLUSION

Polled results yielded that postoperative radiotherapy was promising in improving OS and reducing the locoregional recurrence rate. More large-scale up-to-date RCTs are needed to further validate the use of postoperative radiotherapy in modern practice.

Clinical implementations of 4D pencil beam scanned particle therapy: Report on the 4D treatment planning workshop 2016 and 2017

In 2016 and 2017, the 8th and 9th 4D treatment planning workshop took place in Groningen (the Netherlands) and Vienna (Austria), respectively. This annual workshop brings together international experts to discuss research, advances in clinical implementation as well as problems and challenges in 4D treatment planning, mainly in spot scanned proton therapy. In the last two years several aspects like treatment planning, beam delivery, Monte Carlo simulations, motion modeling and monitoring, QA phantoms as well as 4D imaging were thoroughly discussed. This report provides an overview of discussed topics, recent findings and literature review from the last two years. Its main focus is to highlight translation of 4D research into clinical practice and to discuss remaining challenges and pitfalls that still need to be addressed and to be overcome.

Advances in the use of motion management and image guidance in radiation therapy treatment for lung cancer

The development of advanced radiation technologies, including intensity-modulated radiation therapy (IMRT), stereotactic body radiation therapy (SBRT) and proton therapy, has resulted in increasingly conformal radiation treatments. Recent evidence for the importance of minimizing dose to normal critical structures including the heart and lungs has led to incorporation of these advanced treatment modalities into radiation therapy (RT) for non-small cell lung cancer (NSCLC). While such technologies have allowed for improved dose delivery, implementation requires improved target accuracy with treatments, placing increasing importance on evaluating tumor motion at the time of planning and verifying tumor position at the time of treatment. In this review article, we describe issues and updates related both to motion management and image guidance in the treatment of NSCLC.

Reirradiation for locoregionally recurrent non-small cell lung cancer

Locoregional failure in non-small cell lung cancer (NSCLC) remains high, and the management for recurrent disease in the setting of prior radiotherapy is difficult. Retreatment options such as surgery or systemic therapy are typically limited or frequently result in suboptimal outcomes. Reirradiation (reRT) of thoracic malignancies may be an optimal strategy for providing definitive local control and offering a new chance of cure. Yet, retreatment with radiation therapy can be challenging for fear of excessive toxicities and the inability to safely deliver definitive (≥60 Gy) doses of reRT. However, with recent improvements in radiation delivery techniques and image-guidance, dose-escalation with reRT is possible and outcomes are encouraging. Here, we present a review of various radiation techniques, clinical outcomes and associated toxicities in patients with locoregionally recurrent NSCLC treated primarily with reRT.

A dosimetric phantom study of thoracic radiotherapy based on three-dimensional modeling of mediastinal lymph nodes

The aim of the present study was to investigate the optimal strategy and dosimetric measurement of thoracic radiotherapy based on three-dimensional (3D) modeling of mediastinal lymph nodes (MLNs). A 3D model of MLNs was constructed from a Chinese Visible Human female dataset. Image registration and fusion between reconstructed MLNs and original chest computed tomography (CT) images was conducted in the Eclipse™ treatment planning system (TPS). There were three plans, including 3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), which were designed based on 10 cases of simulated lung lesions (SLLs) and MLNs. The quality of these plans was evaluated via examining indexes, including conformity index (CI), homogeneity index and clinical target volume (CTV) coverage. Dose-volume histogram analysis was performed on SLL, MLNs and organs at risk (OARs). A Chengdu Dosimetric Phantom (CDP) was then drilled at specific MLNs according to 20 patients with thoracic tumors and of a medium-build. These plans were repeated on fused MLNs and CDP CT images in the Eclipse™ TPS. Radiation doses at the SLLs and MLNs of the CDP were measured and compared with calculated doses. The established 3D MLN model demonstrated the spatial location of MLNs and adjacent structures. Precise image registration and fusion were conducted between reconstructed MLNs and the original chest CT or CDP CT images. IMRT demonstrated greater values in CI, CTV coverage and OAR (lungs and spinal cord) protection, compared with 3D-CRT and VMAT (P<0.05). The deviation between the measured and calculated doses was within ± 10% at SLL, and at the 2R and 7th MLN stations. In conclusion, the 3D MLN model can benefit plan optimization and dosimetric measurement of thoracic radiotherapy, and when combined with CDP, it may provide a tool for clinical dosimetric monitoring.

Advances in proton therapy in lung cancer

Lung cancer remains the leading cause of cancer deaths in the United States (US) and worldwide. Radiation therapy is a mainstay in the treatment of locally advanced non-small cell lung cancer (NSCLC) and serves as an excellent alternative for early stage patients who are medically inoperable or who decline surgery. Proton therapy has been shown to offer a significant dosimetric advantage in NSCLC patients over photon therapy, with a decrease in dose to vital organs at risk (OARs) including the heart, lungs and esophagus. This in turn, can lead to a decrease in acute and late toxicities in a population already predisposed to lung and cardiac injury. Here, we present a review on proton treatment techniques, studies, clinical outcomes and toxicities associated with treating both early stage and locally advanced NSCLC.

Acquired resistance to tyrosine kinase inhibitors may be linked with the decreased sensitivity to X-ray irradiation

Acquired resistance to chemotherapy and radiation therapy is one of the major obstacles decreasing efficiency of treatment of the oncologic diseases. In this study, on the two cell lines (ovarian carcinoma SKOV-3 and neuroblastoma NGP-127), we modeled acquired resistance to five target anticancer drugs. The cells were grown on gradually increasing concentrations of the clinically relevant tyrosine kinase inhibitors (TKIs) Sorafenib, Pazopanib and Sunitinib, and rapalogs Everolimus and Temsirolimus, for 20 weeks. After 20 weeks of culturing, the half-inhibitory concentrations (IC₅₀) increased by 25 – 186% for the particular combinations of the drugs and cell types. We next subjected cells to 10 Gy irradiation, a dose frequently used in clinical radiation therapy. For the SKOV-3, but not NGP-127 cells, for the TKIs Sorafenib, Pazopanib and Sunitinib, we noticed statistically significant increase in capacity to repair radiation-induced DNA double strand breaks compared to naïve control cells not previously treated with TKIs. These peculiarities were linked with the increased activation of ATM DNA repair pathway in the TKI-treated SKOV-3, but not NGP-127 cells. Our results provide a new cell culture model for studying anti-cancer therapy efficiency and evidence that there may be a tissue-specific radioresistance emerging as a side effect of treatment with TKIs.