Acute Esophagus Toxicity in Lung Cancer Patients After Intensity Modulated Radiation Therapy and Concurrent Chemotherapy

Genetic profiling in radiotherapy: a comprehensive review

This comprehensive review explores the pivotal role of radiotherapy in cancer treatment, emphasizing the diverse applications of genetic profiling. The review highlights genetic markers for predicting radiation toxicity, enabling personalized treatment planning. It delves into the impact of genetic profiling on radiotherapy strategies across various cancer types, discussing research findings related to treatment response, prognosis, and therapeutic resistance. The integration of genetic profiling is shown to transform cancer treatment paradigms, offering insights into personalized radiotherapy regimens and guiding decisions in cases where standard protocols may fall short. Ultimately, the review underscores the potential of genetic profiling to enhance patient outcomes and advance precision medicine in oncology.

Excessive esophageal toxicity in patients with locally advanced non-small cell lung cancer treated with concurrent hypofractionated chemoradiotherapy and 3-weekly platinum doublet chemotherapy

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Concurrent full dose chemoradiotherapy (24x2.75 Gy) is toxic in multiple N2 disease.

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Toxicity after platinum doublet chemoradiation (24x2.75 Gy) is mainly esophageal.

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Fatal toxicity may be increased in patients with bulky centrally located tumors.

Introduction

Concurrent chemoradiation followed by immunotherapy is the standard of care for patients with stage III non-small cell lung cancer (NSCLC). Prior to the introduction of adjuvant immunotherapy, we treated patients with stage III NSCLC with concurrent platinum doublet chemotherapy and 66 Gy in 24 fractions. We determined the toxicity of this treatment.

Methods

A retrospective observational study was performed in a cohort of patients with stage III NSCLC, <70 years old, and WHO performance score 0–1. Patients were treated with concurrent platinum doublet chemotherapy and 66 Gy in 24 fractions. All patients were staged with a PET-scan and brain MRI-scan. Toxicity was scored using the common criteria for adverse events (CTCAE v4.03).

Results

Between 2012 and 2017, 41 patients were treated with mildly hypofractionated radiotherapy and platinum doublet chemotherapy. The median follow-up was 4.7 years. The median age was 57 and 58% of patients were male. The majority of patients had stage IIIB disease (68%). The median total Gross Tumor Volume (GTV) was 104 cc (range: 15–367 cc). The median lymph node GTV was 59 cc (10–341 cc). Five patients died: four due to an esophagus perforation or fistula, and one due to pulmonary bleeding. Grade ≥ 3 esophageal toxicity occurred in 16 patients. Five patients had late grade ≥ 3 esophageal toxicity (12%). The median overall survival was 19 months.

Conclusion

Toxicity was unexpectedly high in patients with stage III NSCLC (WHO 0–1) after concurrent platinum doublet chemotherapy and 66 Gy in 24 fractions.

Learning healthcare systems and rapid learning in radiation oncology: Where are we and where are we going?

Learning health systems and rapid-learning are well developed at the conceptual level. The promise of rapidly generating and applying evidence where conventional clinical trials would not usually be practical is attractive in principle. The connectivity of modern digital healthcare information systems and the increasing volumes of data accrued through patients' care pathways offer an ideal platform for the concepts. This is particularly true in radiotherapy where modern treatment planning and image guidance offers a precise digital record of the treatment planned and delivered. The vision is of real-world data, accrued by patients during their routine care, being used to drive programmes of continuous clinical improvement as part of standard practice. This vision, however, is not yet a reality in radiotherapy departments. In this article we review the literature to explore why this is not the case, identify barriers to its implementation, and suggest how wider clinical application might be achieved.

Duration of acute esophageal toxicity in concomitant radio-chemotherapy for non-small cell lung cancer with different fractionation schedules

OBJECTIVES

In our previous prospective trial on accelerated hypofractionated concomitant radiochemotherapy (AHRT-CHT) for non-small-cell lung cancer (NSCLC), the incidence of grade ≥3 acute esophageal toxicity (AET) was similar to that reported for conventionally fractionated concomitant radiochemotherapy (CFRT-CHT), but its duration was prolonged. Thus, we aimed to compare the duration of grade ≥3 AET between AHRT-CHT and CFRT-CHT.

METHODS

Clinical data of 76 NSCLC patients treated with CFRT-CHT (60-66 Gy/2 Gy) during 2015-2020 were retrospectively compared with the data of 92 patients treated with AHRT-CHT (58.8 Gy/2.8 Gy) in the prospective trial. The maximum grade of AET, incidence, and duration of grade ≥3 AET were the end points. Univariate and multivariate analyses were applied to correlate clinical and treatment variables with these end points.

RESULTS

Neither the maximum grade of AET (p = 0.71), nor the incidence of grade ≥3 AET (p = 0.87) differed between the two groups. The number of CHT cycles delivered (2 vs 1, p = 0.005) and higher esophagus mean BED (p = 0.009) were significant predictors for a higher maximum grade of AET; older age was a significant predictor for higher incidence of grade ≥3 AET (p = 0.03). The median duration of grade ≥3 AET in AHRT-CHT and CFRT-CHT group was 30 days (range 5-150) vs 7 days (range 3-20), respectively, p = 0.0005. In multivariate analysis, only the AHRT-CHT schedule (p=0.003) was a significant predictor for a longer duration of grade ≥3 AET.

CONCLUSION

Despite similar incidence of grade ≥3 AET, its duration is significantly prolonged in NSCLC patients treated with AHRT-CHT compared to CFRT-CHT.

ADVANCES IN KNOWLEDGE

Reporting only the rate of grade ≥3 AET in clinical trials may underestimate the real extent of the esophageal toxicity; its duration should also be routinely reported.

Hypofractionated Intensity Modulated Radiation Therapy With Concurrent Chemotherapy in Locally Advanced Non-Small Cell Lung Cancer: A Phase II Prospective Clinical Trial (GASTO1011)

PURPOSE

We aimed to explore the efficacy and toxicity of split-course hypofractionated radiotherapy with concurrent chemotherapy (HRT-CHT) in patients with locally advanced non-small cell lung cancer (LANSCLC) in this single-arm, phase II study.

METHODS

LANSCLC patients were considered eligible if their forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC%) and carbon monoxide diffusing capacity (DLCO%) were ≥40% and ≥45%, respectively. HRT-CHT using the IMRT technique was administered with 51 Gy in 17 fractions as the first course followed by a break. Patients without disease progression or persistent ≥grade 2 toxicities had an HRT-CHT of 15-18 Gy in 5-6 fractions as a boost. The primary endpoint was progression-free survival (PFS), and the secondary endpoint was overall survival (OS).

RESULTS

Eighty-nine patients were enrolled and analyzed. The median follow-up was 29.5 months for all patients and 35.3 months for the survivors. The objective response rate was 97.8%; the median PFS and OS were 11.0 months and 27.0 months, respectively. Grade 3 acute esophagitis/pneumonitis occurred in 15 (16.9%)/7 (7.9%) patients. Grade 3/5 late pneumonitis occurred in 2 (2.2%)/1 (1.1%) patients. Of the 78 (87.6%) who completed the split-course HRT-CHT per protocol, patients with better FEV1/FVC% and DLCO% after the break had significantly better OS (for the FEV/FVC1%≥80% vs 60-79% vs 41-59% groups, 2-year OS values were 57.2% vs 56.9% vs 0%, respectively, p=0.024; for the DLCO%≥80% vs 60-79% vs 45-59% groups, 2-year OS values were 70.4% vs 48.4% vs 37.5%, respectively, p=0.049).

CONCLUSIONS

Split-course HRT-CHT achieved a promising response rate and survival with tolerable toxicity in LANSCLC. Pulmonary function tests are necessary indicators for radiation treatment planning and dose escalation.

Towards the Interpretability of Machine Learning Predictions for Medical Applications Targeting Personalised Therapies: A Cancer Case Survey

Artificial Intelligence is providing astonishing results, with medicine being one of its favourite playgrounds. Machine Learning and, in particular, Deep Neural Networks are behind this revolution. Among the most challenging targets of interest in medicine are cancer diagnosis and therapies but, to start this revolution, software tools need to be adapted to cover the new requirements. In this sense, learning tools are becoming a commodity but, to be able to assist doctors on a daily basis, it is essential to fully understand how models can be interpreted. In this survey, we analyse current machine learning models and other in-silico tools as applied to medicine-specifically, to cancer research-and we discuss their interpretability, performance and the input data they are fed with. Artificial neural networks (ANN), logistic regression (LR) and support vector machines (SVM) have been observed to be the preferred models. In addition, convolutional neural networks (CNNs), supported by the rapid development of graphic processing units (GPUs) and high-performance computing (HPC) infrastructures, are gaining importance when image processing is feasible. However, the interpretability of machine learning predictions so that doctors can understand them, trust them and gain useful insights for the clinical practice is still rarely considered, which is a factor that needs to be improved to enhance doctors' predictive capacity and achieve individualised therapies in the near future.

Dosimetric parameters associated with radiation-induced esophagitis in breast cancer patients undergoing regional nodal irradiation

BACKGROUND/PURPOSE

Rates of acute esophagitis in breast cancer patients undergoing regional nodal irradiation (RNI) are under-reported. We set to identify esophageal dose-volume constraints associated with grade 2 esophagitis (G2E). We hypothesized that the G2E rate was higher with intensity modulated radiation therapy (IMRT) vs. 3D conformal radiation therapy (3DCRT).

MATERIALS/METHODS

We identified patients that received RNI (50 Gy/25 fractions) from 1/2013 to 6/2019. We retrospectively contoured the esophagus in a consistent manner and recorded esophageal mean dose, max dose, and V10-V50. Our primary endpoint was the G2E rate. Receiver operating characteristics curves analysis (e.g., Youden's J statistic) were used to determine the cutpoints for the dosimetric parameters which were then tested in logistic regression models.

RESULTS

We identified 531 patients (50% left-sided; 41% IMRT; 16.2% G2E). G2E was significantly higher in IMRT vs. 3DCRT patients (23.6% vs. 10.9%, p < 0.0001). All esophageal dosimetric parameters were significantly associated with G2E after adjusting for age and laterality. The cutpoints for esophageal mean dose, V10 and V20 were 11 Gy, 30%, and 15%, respectively. The associations between the dichotomized dose-volume parameters and G2E were OR = 3.82 (95% CI 2.28-6.40, p < 0.0001) for esophageal mean dose, OR = 5.37 (95% CI 3.01-9.58, p < 0.0001) for esophageal V10, and OR = 3.23 (95% CI 1.93-5.41, p < 0.0001) for esophageal V20.

CONCLUSION

In patients receiving RNI with modern techniques, we found that G2E occurs in >15%, and more frequently with IMRT. These data strongly support the routine contouring of the esophagus in RNI planning, and our constraints should be incorporated in future prospective protocols of RNI.

Predictive Modeling of Thoracic Radiotherapy Toxicity and the Potential Role of Serum Alpha-2-Macroglobulin

Background: To investigate the impact of alpha-2-macroglobulin (A2M), a suspected intrinsic radioprotectant, on radiation pneumonitis and esophagitis using multifactorial predictive models. Materials and Methods: Baseline A2M levels were obtained for 258 patients prior to thoracic radiotherapy (RT). Dose-volume characteristics were extracted from treatment plans. Spearman's correlation (Rs) test was used to correlate clinical and dosimetric variables with toxicities. Toxicity prediction models were built using least absolute shrinkage and selection operator (LASSO) logistic regression on 1,000 bootstrapped datasets. Results: Grade ≥2 esophagitis and pneumonitis developed in 61 (23.6%) and 36 (14.0%) patients, respectively. The median A2M level was 191 mg/dL (range: 94-511). Never/former/current smoker status was 47 (18.2%)/179 (69.4%)/32 (12.4%). We found a significant negative univariate correlation between baseline A2M levels and esophagitis (Rs = -0.18/p = 0.003) and between A2M and smoking status (Rs = 0.13/p = 0.04). Further significant parameters for grade ≥2 esophagitis included age (Rs = -0.32/p < 0.0001), chemotherapy use (Rs = 0.56/p < 0.0001), dose per fraction (Rs = -0.57/p < 0.0001), total dose (Rs = 0.35/p < 0.0001), and several other dosimetric variables with Rs > 0.5 (p < 0.0001). The only significant non-dosimetric parameter for grade ≥2 pneumonitis was sex (Rs = -0.32/p = 0.037) with higher risk for women. For pneumonitis D15 (lung) (Rs = 0.19/p = 0.006) and D45 (heart) (Rs = 0.16/p = 0.016) had the highest correlation. LASSO models applied on the validation data were statistically significant and resulted in areas under the receiver operating characteristic curve of 0.84 (esophagitis) and 0.78 (pneumonitis). Multivariate predictive models did not require A2M to reach maximum predictive power. Conclusion: This is the first study showing a likely association of higher baseline A2M values with lower risk of radiation esophagitis and with smoking status. However, the baseline A2M level was not a significant risk factor for radiation pneumonitis.

Quantifying the Interfractional motion of Esophagus Using Daily Cone Beam Computed Tomography with Oral Contrast During Radiation Therapy for Locally Advanced Non-Small Cell Lung Cancer

PURPOSE

To quantify the interfractional motion of the esophagus during fractionated radiation therapy for locally advanced non-small cell lung cancer.

METHODS AND MATERIALS

We registered simulation 4-dimensional computed tomography (CT) and daily cone beam CT (CBCT) and documented the motion of the esophagus centroid at 5-mm interval slices in right-left (RL) and anterior-posterior (AP) directions. Oral barium sulfate was administrated during CBCT to help localize the esophagus. Thirty-five patients were enrolled. Thirty-five 4-dimensional CT scans, 595 CBCT scans, and 25,970 slices were analyzed. The slice-derived motion values for all patients were presented as 2.5 to 97.5 percentiles and ranges stratified by segments. The magnitude of motion for each individual patient was defined as the standard deviation (SD) of daily motion values stratified by segments. Correlations between the magnitude of motion and clinical variables were explored.

RESULTS

The 2.5 to 97.5 percentiles of RL and AP motion were -4.2 to 7.1 and -4.4 to 5.1; -10.3 to 6.0 and -4.3 to 3.8; -8.7 to 5.5 and -6.4 to 2.8; and -9.1 to 4.7 and -5.8 to 3.3 mm for cervical, proximal, middle, and distal thoracic esophagus, respectively. The interfractional motion was direction- and location-dependent. The magnitude of RL motion was greater than that of AP motion for the 4 segments (P < .05). In the RL direction, the magnitude of motion was greater for the middle thoracic esophagus than for the cervical (median SD 2.7 vs 2.0 mm, P = .001) and proximal thoracic esophagus (median SD 2.7 vs 2.1 mm, P = .002). Patients with right lung tumor and bulky lymph nodes tended to display greater RL esophageal motion.

CONCLUSIONS

The interfractional motion of the esophagus can be considerable during radiation therapy in locally advanced non-small cell lung cancer, especially for middle thoracic esophagus in RL direction. Strategies to minimize the effect of interfractional esophageal motion on dosimetry should be considered.

The use of real-world evidence to audit normal tissue complication probability models for acute esophageal toxicity in non-small cell lung cancer patients

INTRODUCTION

The aim of this work is to assess the validity of real world data (RWD) derived from an electronic toxicity registration (ETR). As a showcase, the NTCP-models of acute esophageal toxicity (AET) for concurrent chemoradiation (CCRT) for NSCLC patients were used to validate the ETR of AET before/after dose de-escalation to the mediastinal lymph nodes.

MATERIAL AND METHODS

One hundred and one patients received 24 × 2.75 Gy and 116 patients received de-escalated dose of 24 × 2.42 Gy to the mediastinal lymph nodes. The validity and completeness of the ETR was analyzed. The grade ≥2 AET probability was defined according the V50 Gy and V60 Gy NTCP-models from literature. Validity of the models was assessed by calibration and discrimination. Furthermore, sensitivity and specificity for different cut-off points were determined.

RESULTS

The compliance of ETR was 73-80%, with sensitivity and specificity rates of 83% and 86% for grade ≥2 AET, respectively. Discrimination of both NTCP-models demonstrated a moderate accuracy (V50 model, AUC 0.71; V60-model, AUC 0.69). Dose de-escalation did not influence the accuracy of the V50-model; AUC before: 0.69, and AUC after: 0.71. For the V60-model the model-accuracy decreased after dose de-escalation; AUC before: 0.72 and AUC after: 0.62, respectively.

CONCLUSION

RWD is a useful method to audit NTCP models in clinical practice. The NTCP models to predict AET in NSCLC patients showed moderate predictive accuracy. For clinical practice, the V50Gy seems to be most stable for dose de-escalation without compromising safety and efficacy.

Dose-volume predictors of early esophageal toxicity in non-small cell lung cancer patients treated with accelerated-hyperfractionated radiotherapy

BACKGROUND AND PURPOSE

Early radiation-induced esophageal toxicity (RIET) is one of the major side effects in patients with non-small cell lung cancer (NSCLC) and can be a reason for treatment interruptions. As the age of patients with NSCLC and corresponding comorbidities continue to increase, primary radiotherapy alone is a commonly used alternative treatment in these cases. The aim of the present study is to compare dosimetric and clinical parameters from the previously reported CHARTWEL trial for their ability to predict esophagitis and investigate potential differences in the accelerated and conventional fractionation arm.

MATERIAL AND METHODS

146 patients of the Dresden cohort of the randomized phase III CHARTWEL trial were included in this post-hoc analysis. Side effects were prospectively scored weekly during the first 8 weeks from start of radiotherapy. To compare both treatment arms, recorded dose-volume parameters were adjusted for the different fractionation schedules. Logistic regression was performed to predict early RIET for the entire study group as well as for the individual treatment arms. Different dosimetric and clinical parameters were tested.

RESULTS

Patients receiving the accelerated CHARTWEL schedule experienced earlier and more severe esophagitis (e.g. 20.5% vs. 9.6% ≥grade 2 at week 3, respectively). In contrast, the median time period for recovery of grade 1 esophagitis was significantly longer for patients with conventional fractionation compared to the CHARTWEL group (median [range]: 21 [12-49] days vs. 15 [7-84] days, p = 0.028). In univariable logistic regression none of the dose-volume parameters showed a significant correlation with early RIET grade ≥ 2 in the conventional irradiation group. In contrast, for patients receiving CHARTWEL, the physical dose-volumes parameters V₄₀ and V₅₀; and re-scaled values V_EQD2,50 and V_EQD2,60 were significant predictors of early RIET grade ≥ 2. Dose-volume parameters remained different between CHARTWEL and conventional fractionation even after biological rescaling.

CONCLUSION

Our results show a more dominant dose-volume effect in the CHARTWEL arm compared to conventional fractionation, especially for higher esophageal doses. These findings support the notion that dose-volume parameters for radiation esophagitis determined in a specific and time dependent setting of field arrangements can not be easily transferred to another setting. In clinical practice esophageal volumes receiving 40 Gy or more should be strictly limited in hyperfractionated-accelerated fraction schemes.

Radioprotective effects of mistletoe extract in zebrafish embryos in vivo

Introduction: Radioprotectors can enhance the efficacy of cancer radiotherapy, but their clinical use remains uncommon. The present study aimed to assess the radioprotective potential of mistletoe extract (commercial name: Abnoba Viscum), a well-known complementary cancer medicine, in zebrafish larvae. Materials and methods: Wild-type AB zebrafish embryos at 4 h-post-fertilization were exposed to 5 Gy 9-MeV electron beam irradiation after being treated for 1 h with 4 mMl/L amifostine or 0.2 mg/ml Abnoba Viscum A, F, M, or Q. Primary endpoints were abnormality-free survival and abnormality-free rates among survivors at 5 days-post-fertilization. Results: The crude abnormality-free survival rates were 33.7%, 49.0%, 38.8%, 43.9%, 38.1%, and 52.6%, whereas abnormality-free rates among survivors were 36.4%, 49.6%, 37.8%, 45.6%, 52.0%, and 62.8% for the control (with no pharmacologic treatment), amifostine, Abnoba Viscum A, F, M, and Q groups, respectively. Abnormality-free survival rates in the amifostine and Abnoba Viscum Q groups were significantly different from those in the control (p = .040 and .012, respectively), with an odds ratio (OR) of 1.90 [95% confidence interval (CI): 1.03-3.51] and 2.20 (95% CI: 1.19-4.08), respectively. Abnormality-free rates among survivors in the amifostine and Abnoba Viscum M and Q groups were significantly different from those in the control group (p = .048, .042, and <.001, respectively), with an OR of 1.79 (95% CI: 1.00-3.20), 1.82 (95% CI: 1.02-3.26), and 2.98 (1.67-5.33), respectively. Conclusion: Abnoba Viscum Q has at least a similar radioprotective effect to that of amifostine. Mistletoe extracts have been clinically applied for a long time and their effectiveness and feasibility have been verified. Abnoba Viscum Q might be a new candidate radioprotectant to enhance cancer radiotherapy efficacy.

A Quantitative Clinical Decision-Support Strategy Identifying Which Patients With Oropharyngeal Head and Neck Cancer May Benefit the Most From Proton Radiation Therapy

PURPOSE

Developing a quantitative decision-support strategy estimating the impact of normal tissue complications from definitive radiation therapy (RT) for head and neck cancer (HNC). We developed this strategy to identify patients with oropharyngeal HNC who may benefit most from receiving proton RT.

METHODS AND MATERIALS

Recent normal tissue complication probability (NTCP) models for dysphagia, esophagitis, hypothyroidism, xerostomia, and oral mucositis were used to estimate NTCP for 33 patients with oropharyngeal HNC previously treated with photon intensity modulated radiation therapy (IMRT). Comparative proton therapy plans were generated using clinical protocols for HNC RT at a collaborating proton center. Organ-at-risk (OAR) doses from photon and proton RT plans were used to calculate NTCPs; Monte Carlo sampling 10,000 times was used for each patient to account for model parameter uncertainty. The latency and duration of each complication were modeled from calculated NTCP, accounting for age-, sex-, smoking- and p16-specific conditional survival probability. Complications were then assigned quality-adjustment factors based on severity to calculate quality-adjusted life years (QALYs) lost from each complication.

RESULTS

Based on our institutional-delivered photon IMRT doses and the achievable proton therapy doses, the average QALY reduction from all HNC RT complications for photon and proton therapy was 1.52 QALYs versus 1.15 QALYs, with proton therapy sparing 0.37 QALYs on average (composite 95% confidence interval, 0.27-2.53 QALYs). Long-term complications (dysphagia and xerostomia) contributed most to the QALY reduction. The QALYs spared with proton RT varied considerably among patients, ranging from 0.06 to 0.84 QALYs. Younger patients with p16-positive tumors who smoked ≤10 pack-years may benefit most from proton therapy, although this finding should be validated using larger patient series. A sensitivity analysis reducing photon IMRT doses to all OARs by 20% resulted in no overall estimated benefit with proton therapy with -0.02 QALYs spared, although some patients still had an estimated benefit in this scenario, ranging from -0.50 to 0.43 QALYs spared.

CONCLUSIONS

This quantitative decision-support strategy allowed us to identify patients with oropharyngeal cancer who might benefit the most from proton RT, although the estimated benefit of proton therapy ultimately depends on the OAR doses achievable with modern photon IMRT solutions. These results can help radiation oncologists and proton therapy centers optimize resource allocation and improve quality of life for patients with HNC.

Clinical, dosimetric, and position factors for radiation-induced acute esophagitis in intensity-modulated (chemo)radiotherapy for locally advanced non-small-cell lung cancer

Purpose

The purpose of this study was to estimate the relation between acute esophagitis (AE) and clinical, dosimetric, and position factors in patients with locally advanced non-small-cell lung cancer (NSCLC) receiving intensity-modulated (chemo)radiotherapy.

Materials and methods

A retrospective cohort analysis was performed to identify factors associated with Common Toxicity Criteria for Adverse Events grade 2 or worse AE (AE2+). A multivariable model was established including patient- and treatment-related variables and esophageal dose–volume histogram parameters. The esophagus was divided according to physiological anatomy, and logistic regression was used to analyze the position parameter for its correlation with AE2+.

Results

The incidence of AE2+ was 27.5%. All models included gender, concurrent chemo-radiotherapy (CCRT), position parameter, and one of the dosimetric variables. The model with mean dose showed the best goodness of fit. Gender (OR=2.47, P=0.014), CCRT (OR=3.67, P=0.015), mean dose (OR=1.33, P<0.001), and maximum radiation position (OR=1.65, P=0.016) were significantly related to AE2+.

Conclusion

Gender, concurrent chemotherapy, maximum radiation position, and mean dose were independent risk factors for AE2+. The upper part of the esophagus showed a higher sensitivity to radiation toxicity.

Revisiting the dose constraints for head and neck OARs in the current era of IMRT

Head and neck cancer poses a particular challenge in radiation therapy, whilst being an effective treatment modality it requires very high doses of radiation to provide effective therapy. This is further complicated by the fact that the head and neck region contains a large number of radiosensitive tissues, often resulting in patients experiencing debilitating normal tissue complications. In the era of intensity-modulated radiation therapy (IMRT) treatments can be delivered using non-uniform dose distributions selectively aimed at reducing the dose to critical organs-at-risk while still adequately covering the tumor target. Dose-volume constraints for the different risk organs play a vital role in one's ability to devise the best IMRT treatment plan for a head and neck cancer patient. To this end, it is pivotal to have access to the latest and most relevant dose constraints available and as such the goal of this review is to provide a summary of suggested dose-volume constraints for head and neck cancer RT that have been published after the QUANTEC reports were made available in early 2010.

Predictive relevance of ncRNAs in non-small-cell lung cancer patients with radiotherapy: a review of the published data

Radiotherapy is one of the most commonly used methods to treat non-small-cell lung cancer. However, radiotherapy, especially thoracic radiotherapy, is always accompanied by radiation-induced complications or radioresistance. In this regard, ncRNAs, including miRNAs and lncRNAs, have received considerable interest for their predictive relevance. This review article illustrates the recent findings about the possible involvement of ncRNAs, mainly miRNAs and lncRNAs, in radioresistance and radiation-induced complications and their potential use for predicting radiation-induced complications and radiotherapy response.

Twice-daily Thoracic Radiotherapy for Limited-stage Small-cell Lung Cancer Does Not Increase the Incidence of Acute Severe Esophagitis

PURPOSE

Acute esophagitis is common after thoracic radiation therapy (TRT) given with chemotherapy for limited-stage small-cell lung cancer (LS SCLC). Although twice-daily TRT to 45 Gy in 30 fractions is considered standard, some clinicians are reluctant to use this schedule because of its perceived impracticality and risk of severe esophagitis. We reviewed a single-institution experience with severe (grade ≥ 3) esophagitis after TRT with chemotherapy for LS SCLC.

PATIENTS AND METHODS

A total of 504 patients were identified as having received TRT (≥45 Gy) with platinum-containing chemotherapy for LS SCLC at MD Anderson Cancer Center in 1987 through 2012. Patients with complete or good partial response were offered prophylactic cranial irradiation. Esophagitis was scored retrospectively with the Common Terminology Criteria for Adverse Events, V3.0. Clinical variables were analyzed for possible association with acute grade ≥ 3 esophagitis.

RESULTS

At a median follow-up time of 23.9 months (range, 1.2-240.8 months), 103 (20%) patients had experienced grade ≥ 3 esophagitis. In univariate analysis, TRT dose ≥ 60 Gy was the only factor associated with severe esophagitis (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.02-3.30; P = .043); use of twice-daily TRT was not (OR, 0.96; 95% CI, 0.61-1.52; P = .867). The significance of TRT to ≥ 60 Gy was maintained in multivariate Cox regression analysis adjusted for tumor size (OR, 1.91; 95% CI, 1.05-3.46; P = .034).

CONCLUSIONS

TRT to ≥ 60 Gy predicted acute severe esophagitis, but twice-daily fractionation did not. Standard-dose 45-Gy twice-daily TRT should not be avoided for fear of severe esophagitis.

Machine learning algorithms for outcome prediction in (chemo)radiotherapy: An empirical comparison of classifiers

Purpose:

Machine learning classification algorithms (classifiers) for prediction of treatment response are becoming more popular in radiotherapy literature. General Machine learning literature provides evidence in favor of some classifier families (random forest, support vector machine, gradient boosting) in terms of classification performance. The purpose of this study is to compare such classifiers specifically for (chemo)radiotherapy datasets and to estimate their average discriminative performance for radiation treatment outcome prediction.

Methods:

We collected 12 datasets (3496 patients) from prior studies on post-(chemo)radiotherapy toxicity, survival, or tumor control with clinical, dosimetric, or blood biomarker features from multiple institutions and for different tumor sites, that is, (non-)small-cell lung cancer, head and neck cancer, and meningioma. Six common classification algorithms with built-in feature selection (decision tree, random forest, neural network, support vector machine, elastic net logistic regression, Logit-Boost) were applied on each dataset using the popular open-source R package caret. The R code and documentation for the analysis are available online (https://github.com/timodeist/classifier_selection_code). All classifiers were run on each dataset in a 100-repeated nested fivefold cross-validation with hyperparameter tuning. Performance metrics (AUC, calibration slope and intercept, accuracy, Cohen’s kappa, and Brier score) were computed. We ranked classifiers by AUC to determine which classifier is likely to also perform well in future studies. We simulated the benefit for potential investigators to select a certain classifier for a new dataset based on our study (pre-selection based on other datasets) or estimating the best classifier for a dataset (set-specific selection based on information from the new dataset) compared with uninformed classifier selection (random selection).

Results:

Random forest (best in 6/12 datasets) and elastic net logistic regression (best in 4/12 datasets) showed the overall best discrimination, but there was no single best classifier across datasets. Both classifiers had a median AUC rank of 2. Preselection and set-specific selection yielded a significant average AUC improvement of 0.02 and 0.02 over random selection with an average AUC rank improvement of 0.42 and 0.66, respectively.

Conclusion:

Random forest and elastic net logistic regression yield higher discriminative performance in (chemo)radiotherapy outcome and toxicity prediction than other studied classifiers. Thus, one of these two classifiers should be the first choice for investigators when building classification models or to benchmark one’s own modeling results against. Our results also show that an informed preselection of classifiers based on existing datasets can improve discrimination over random selection.

The potential for increased tumor control probability in non-small cell lung cancer with a hypofractionated integrated boost to the gross tumor volume

Treatment outcomes in locally advanced non-small cell lung cancer (NSCLC) to date have been poor, with normal tissue toxicity often limiting the dose that can be delivered to the tumor. Treatment intensification in NSCLC via targeted dose escalation with modern delivery techniques may offer the potential for a significant increase in tumor control probability (TCP) without a clinically significant increase in organ-at-risk (OAR) toxicity. In this planning study, 20 patients were re-planned with a volumetric modulated arc therapy (VMAT) and an inhomogeneous dose distribution with iteratively escalated doses to the gross tumor volume (iGTV) (composite GTV across multiple 4-dimensional computed tomography [4DCT] phases) in a series of 20 fraction regimes. For each plan OAR doses, target coverage and predicted TCPs were collected and compared with homogenous 3-dimensional (3D) and VMAT plans, as well as with each other. In 70% of patients, it was possible to escalate to 75 Gy in 20 fractions within OAR tolerances, opening the possibility of treating these patients to a biological effective dose (BED) of 103.1 Gy₁₀. This planning study forms the basis of a clinical trial INTENSE (Inhomogeneous Targeted Dose Escalation in Non-Small CEll Lung Cancer), CTRIAL 15-47.

Systematic Review of Normal Tissue Complication Models Relevant to Standard Fractionation Radiation Therapy of the Head and Neck Region Published After the QUANTEC Reports

There has recently been an increasing interest in model-based evaluation and comparison of different treatment options in radiation oncology studies. This is partly driven by the considerable technical advancements in radiation therapy of the last decade, leaving radiation oncologists with a multitude of options to consider. In lieu of randomized trials comparing all of these different treatment options for varying indications, which is unfeasible, treatment evaluations based on normal tissue complication probability (NTCP) models offer a practical alternative. The Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) effort, culminating in a number of reports published in 2010, provided a basis for many of the since-implemented dose-response models and dose-volume constraints and was a key component for model-based treatment evaluations. Given that 7 years have passed since the QUANTEC publications and that patient-reported outcomes have emerged as an important consideration in recent years, an updated summary of the published radiation dose-response literature, which includes a focus on patient-reported quality of life outcomes, is warranted. Here we provide a systematic review of quantitative dose-response models published after January 1, 2010 for endpoints relevant to radiation therapy for head and neck cancer, because these patients are typically at risk for a variety of treatment-induced normal tissue complications.

Subjective Global Assessment (SGA) Score Could Be a Predictive Factor for Radiation Pneumonitis in Lung Cancer Patients With Normal Pulmonary Function Treated by Intensity-Modulated Radiation Therapy and Concurrent Chemotherapy

INTRODUCTION

To investigate the relationship between malnutrition and the severity of radiation pneumonitis (RP) in patients with lung cancer with normal baseline pulmonary function and lungs' V20 < 35% treated by intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy.

MATERIALS AND METHODS

A total of 150 patients with lung cancer who received definitive IMRT (≥ 60 Gy) and concurrent chemotherapy were enrolled. In the condition of normal baseline pulmonary function and strict constraints of the irradiation dose to normal lung tissues, we recorded Eastern Cooperative Oncology Group score; concurrent chemotherapy; clinical stage; the level of albumin (ALB), hemoglobin, and C-reactive protein; Subjective Global Assessment (SGA) scores; radiation esophagitis grade; V20 of lungs; and mean lung dose. These factors were correlated with RP using univariate and multivariate regression analyses.

RESULTS

Of 150 patients, 12 patients (8.0%) developed Grade 3 to 5 RP, 37 (24.6%) patients developed grade 3 to 5 esophageal toxicity. In univariate analysis, ALB level (P = .002), radiation esophagitis (P < .001), and SGA score (P < .001) were significantly associated with RP. Multivariate analysis revealed that SGA (P < .001) was the independent predictor of RP.

CONCLUSIONS

SGA could be a predictor for RP in patients with lung cancer treated with definitive IMRT and concurrent chemotherapy.

A Novel Methodology using CT Imaging Biomarkers to Quantify Radiation Sensitivity in the Esophagus with Application to Clinical Trials

Personalized cancer therapy seeks to tailor treatment to an individual patient's biology. Therefore, a means to characterize radiosensitivity is necessary. In this study, we investigated radiosensitivity in the normal esophagus using an imaging biomarker of radiation-response and esophageal toxicity, esophageal expansion, as a method to quantify radiosensitivity in 134 non-small-cell lung cancer patients, by using K-Means clustering to group patients based on esophageal radiosensitivity. Patients within the cluster of higher response and lower dose were labelled as radiosensitive. This information was used as a variable in toxicity prediction modelling (lasso logistic regression). The resultant model performance was quantified and compared to toxicity prediction modelling without utilizing radiosensitivity information. The esophageal expansion-response was highly variable between patients, even for similar radiation doses. K-Means clustering was able to identify three patient subgroups of radiosensitivity: radiosensitive, radio-normal, and radioresistant groups. Inclusion of the radiosensitive variable improved lasso logistic regression models compared to model performance without radiosensitivity information. Esophageal radiosensitivity can be quantified using esophageal expansion and K-Means clustering to improve toxicity prediction modelling. Finally, this methodology may be applied in clinical trials to validate pre-treatment biomarkers of esophageal toxicity.

Different definitions of esophagus influence esophageal toxicity prediction for esophageal cancer patients administered simultaneous integrated boost versus standard-dose radiation therapy

We aim to evaluate whether different definitions of esophagus (DEs) impact on the esophageal toxicity prediction for esophageal cancer (EC) patients administered intensity-modulated radiation therapy with simultaneous integrated boost (SIB-IMRT) vs. standard-dose IMRT (SD-IMRT). The esophagus for 21 patients diagnosed with primary EC were defined in the following four ways: the whole esophagus, including the tumor (ESO_whole); ESO_whole within the treatment field (ESO_infield); ESO_infield, excluding the tumor (ESO_{infield-tumor}) and ESO_whole, excluding the tumor (ESO_whole-tumor). The difference in the dose variation, acute esophageal toxicity (AET) and late esophageal toxicity (LET) of four DEs were compared. We found that the mean esophageal dose for ESO_whole, ESO_infield, ESO_{infield-tumor} and ESO_whole-tumor were increased by 7.2 Gy, 10.9 Gy, 4.6 Gy and 2.0 Gy, respectively, in the SIB-IMRT plans. Radiobiological models indicated that a grade ≥ 2 AET was 2.9%, 3.1%, 2.2% and 1.6% higher on average with the Kwint model and 14.6%, 13.2%, 7.2% and 3.4% higher with the Wijsman model for the four DEs. A grade ≥ 3 AET increased by 4.3%, 7.2%, 4.2% and 1.2%, respectively. Additionally, the predicted LET increased by 0.15%, 0.39%, 1.2 × 10⁻²% and 1.5 × 10⁻³%. Our study demonstrates that different DEs influence the esophageal toxicity prediction for EC patients administered SIB-IMRT vs. SD-IMRT treatment.

Radiobiological evaluation of simultaneously dose-escalated versus non-escalated intensity-modulated radiation therapy for patients with upper thoracic esophageal cancer

OBJECTIVE

To compare the radiobiological response between simultaneously dose-escalated and non-escalated intensity-modulated radiation therapy (DE-IMRT and NE-IMRT) for patients with upper thoracic esophageal cancer (UTEC) using radiobiological evaluation.

METHODS

Computed tomography simulation data sets for 25 patients pathologically diagnosed with primary UTEC were used in this study. DE-IMRT plan with an escalated dose of 64.8 Gy/28 fractions to the gross tumor volume (GTV) and involved lymph nodes from 25 patients pathologically diagnosed with primary UTEC, was compared to an NE-IMRT plan of 50.4 Gy/28 fractions. Dose-volume metrics, tumor control probability (TCP), and normal tissue complication probability for the lung and spinal cord were compared. In addition, the risk of acute esophageal toxicity (AET) and late esophageal toxicity (LET) were also analyzed.

RESULTS

Compared with NE-IMRT plan, we found the DE-IMRT plan resulted in a 14.6 Gy dose escalation to the GTV. The tumor control was predicted to increase by 31.8%, 39.1%, and 40.9% for three independent TCP models. The predicted incidence of radiation pneumonitis was similar (3.9% versus 3.6%), and the estimated risk of radiation-induced spinal cord injury was extremely low (<0.13%) in both groups. Regarding the esophageal toxicities, the estimated grade ≥2 and grade ≥3 AET predicted by the Kwint model were increased by 2.5% and 3.8%. Grade ≥2 AET predicted using the Wijsman model was increased by 14.9%. The predicted incidence of LET was low (<0.51%) in both groups.

CONCLUSION

Radiobiological evaluation reveals that the DE-IMRT dosing strategy is feasible for patients with UTEC, with significant gains in tumor control and minor or clinically acceptable increases in radiation-induced toxicities.

Predictors for severe acute esophagitis in lung cancer patients treated with chemoradiotherapy: a systematic review

PURPOSE

To identify the risk factors for severe acute esophagitis (AE) in lung cancer patients undergoing chemoradiotherapy (CRT).

METHODS

Articles from PubMed, EMBASE, and the Cochrane Library were searched in August 2015. Articles reporting studies of the predictors for severe AE in lung cancer patients after CRT were included. Study quality was assessed using a modified quality assessment tool that was designed previously for an observational study. The effects of studies were combined with the study quality score using a best-evidence synthesis model. Severe AE incidence was also performed using the Metafor package of R-2.11.1.

RESULTS

A total of nine observational studies involving 1641 patients were included. The estimated incidence of severe AE was 14%. According to the best-evidence synthesis criteria, there were two strong-evidence risk factors for severe AE, which were the use of concurrent chemotherapy (CCT) and dose volume histogram (DVH). We also identified four limited-evidence risk factors.

CONCLUSIONS

More attention should be paid to the levels of patients' esophagus function. Although there is no conclusive evidence for severe AE in lung cancer patients after CRT, the above-mentioned factors provide evidence to guide clinicians as to which patients will have severe AE and to choose an optimal prophylactic strategy.

Oesophagus side effects related to the treatment of oesophageal cancer or radiotherapy of other thoracic malignancies

The oesophagus as a serial organ located in the central chest is frequent subject to "incidental" dose application in radiotherapy for several thoracic malignancies including oesophageal cancer itself. Especially due to the radiosensitive mucosa severe radiotherapy induced sequelae can occur, acute oesophagitis and strictures as late toxicity being the most frequent side-effects. In this review we focus on oesophageal side effects derived from treatment of gastrointestinal cancer and secondly provide an overview on oesophageal toxicity from conventional and stereotactic fractionated radiotherapy to the thoracic area in general. Available data on pathogenesis, frequency, onset, and severity of oesophageal side effects are summarized. Whereas for conventional radiotherapy the associations of applied doses to certain volumes of the oesophagus are well described, the tolerance dose to the mediastinal structures for hypofractionated therapy is unknown. The review provides available attempts to predict the risk of oesophageal side effects from dosimetric parameters of SBRT.

Overcoming toxicity-challenges in chemoradiation for non-small cell lung cancer

Concurrent chemoradiation (CCRT) is the treatment of choice for locally advanced non-small cell lung cancer (NSCLC) with a modest survival benefit over sequential chemoradiation or radiotherapy (SCRT) alone. However, this benefit is at the cost of increasing acute toxicity such as esophagitis. Previous analysis revealed several predictive parameters in dose-volume and patient characteristics which helped us to identify those patients at risk for severe esophagus toxicity. As a result, supportive care interventions including individualized patient information, dietary guidance, adequate medication, hydration and tubefeeding could be initiated. This paper discusses the challenges in overcoming chemoradiation induced acute esophageal toxicity (AET).

Dosimetric evaluation of a simple planning method for improving intensity-modulated radiotherapy for stage III lung cancer

This study aimed to evaluate the dosimetric outcomes of a base-dose-plan-compensation (BDPC) planning method for improving intensity-modulated radiotherapy (IMRT) for stage III lung cancer. For each of the thirteen included patients, three types of planning methods were applied to obtain clinically acceptable plans: (1) the conventional optimization method (CO); (2) a split-target optimization method (STO), in which the optimization objectives were set higher dose for the target with lung density; (3) the BDPC method, which compensated for the optimization-convergence error by further optimization based on the CO plan. The CO, STO and BDPC methods were then compared regarding conformity index (CI), homogeneity index (HI) of the target, organs at risk (OARs) sparing and monitor units (MUs). The BDPC method provided better HI/CI by 54%/7% on average compared to the CO method and by 38%/3% compared to the STO method. The BDPC method also spared most of the OARs by up to 9%. The average MUs of the CO, STO and BDPC plans were 890, 937 and 1023, respectively. Our results indicated that the BDPC method can effectively improve the dose distribution in IMRT for stage III lung cancer, at the expense of more MUs.

Multi-criteria optimization achieves superior normal tissue sparing in a planning study of intensity-modulated radiation therapy for RTOG 1308-eligible non-small cell lung cancer patients

PURPOSE

In this planning study, we studied the benefit of intensity-modulated radiation therapy (IMRT) with multi-criteria optimization (MCO) in locally advanced non-small cell lung carcinoma (NSCLC).

METHODS

We selected 10 consecutive patients with gross tumor within 1cm of the esophagus eligible for RTOG 1308, randomized phase II trial of 70 Gy protons vs photons. Planning was performed per protocol. In addition, a novel approach for esophagus sparing was applied by making the contralateral esophagus (CE) an avoidance structure. MCO and non-MCO plans underwent double-blinded review. Plan differences in dose-volume histogram parameters were analyzed.

RESULTS

Median plan differences were mean lung dose=0.8 Gy (p=0.01), lung V20=1.1% (p=0.06), heart V30=1.0% (p=0.03), heart V45=0.6% (p=0.03), esophagus V60=1.2% (p=0.04), and CE V45=3.2% (p=0.01), all favoring MCO over non-MCO. PTV coverage with 95% dose was ⩾98.0% for both plans. There were 5 minor protocol deviations with non-MCO plans and 2 with MCO. Median improvement of active planning time with MCO was 88 min (p<0.01). Physicians preferred 8 MCO and 2 non-MCO plans (p=0.04).

CONCLUSIONS

MCO plans yielded significant improvements in organ-at-risk sparing without compromising target coverage, consumed less dosimetrist time, and were preferred by physicians. We suggest incorporating MCO into prospective clinical trials.

Advances in dosimetry and biological predictors of radiation-induced esophagitis

OBJECTIVE

To summarize the research progress about the dosimetry and biological predictors of radiation-induced esophagitis.

METHODS

We performed a systematic literature review addressing radiation esophagitis in the treatment of lung cancer published between January 2009 and May 2015 in the PubMed full-text database index systems.

RESULTS

Twenty-eight eligible documents were included in the final analysis. Many clinical factors were related to the risk of radiation esophagitis, such as elder patients, concurrent chemoradiotherapy, and the intense radiotherapy regimen (hyperfractionated radiotherapy or stereotactic body radiotherapy). The parameters including Dmax, Dmean, V20, V30, V50, and V55 may be valuable in predicting the occurrence of radiation esophagitis in patients receiving concurrent chemoradiotherapy. Genetic variants in inflammation-related genes are also associated with radiation-induced toxicity.

CONCLUSION

Dosimetry and biological factors of radiation-induced esophagitis provide clinical information to decrease its occurrence and grade during radiotherapy. More prospective studies are warranted to confirm their prediction efficacy.

Acute esophagitis for patients with local-regional advanced non small cell lung cancer treated with concurrent chemoradiotherapy

PURPOSE

Esophagitis is common in patients treated with definitive radiotherapy for local-regional advanced non small cell lung cancer (NSCLC). The purpose of this study was to estimate the dose-effect relationship using clinical and dosimetric parameters in patients receiving intensity modulated radiotherapy (IMRT) and concomitant chemotherapy (CCT).

METHODS

Between 2009 and 2013, 117 patients with stages IIB-IIIB NSCLC were treated in a multicenter randomized phase II trial with 2 cycles of induction chemotherapy followed by IMRT and CCT. The esophagitis was prospectively scored using the Common Toxicity Criteria 3.0. Clinical and dosimetric variables were analyzed for the correlation with grade ⩾2 esophagitis through logistic regression.

RESULTS

Grade 2 esophagitis was experienced by 31 (27%). All models including gender, institution, a dosimetric parameter and a position parameter were significantly associated with esophagitis. The two models using the relative esophagus volume irradiated above 40 Gy (V40, OR=2.18/10% volume) or the length of esophagus irradiated above 40 Gy (L40, OR=4.03/5 cm) were optimal. The upper part of esophagus was more sensitive and females experienced more toxicity than men.

CONCLUSION

V40 and L40 were most effective dosimetric predictors of grade ⩾2 esophagitis. The upper part of esophagus was more sensitive.

Simultaneously modulated accelerated radiation therapy reduces severe oesophageal toxicity in concomitant chemoradiotherapy of locally advanced non-small-cell lung cancer

OBJECTIVE

The aim of this study was to evaluate the potential of simultaneously modulated accelerated radiation therapy (SMART) to reduce the incidence of severe acute oesophagitis in the treatment of unresectable locally advanced non-small-cell lung cancer (LANSCLC).

METHODS

21 patients were treated with SMART and concomitant platinum-based chemotherapy. The prescribed doses were limited to 54 Gy at 1.8 Gy per day to the zones of presumed microscopic extent while simultaneously maintaining doses of 66 Gy at 2.2 Gy per day to the macroscopic disease. The whole treatment was delivered over 30 fractions and 6 weeks. Dosimetric parameters of SMART and the standard technique of irradiation [intensity-modulated radiation therapy (IMRT)] were compared. Acute toxicity was prospectively recorded.

RESULTS

The highest grade of oesophagitis was 62% (13 patients) grade 1, 33% (7 patients) grade 2 and 5% (1 patient) grade 3. Three (14%) patients experienced acute grade 2 pneumonitis. There was no grade 4 oesophageal or pulmonary toxicity. Doses to the organs at risk were significantly reduced in SMART compared with IMRT [oesophagus: V50Gy, 28.5 Gy vs 39.9 Gy (p = 0.003); V60Gy, 7.1 Gy vs 30.7 Gy (p = 0.003); lung: V20Gy, 27.4 Gy vs 30.1 Gy (p = 0,002); heart: V40Gy, 7.3 Gy vs 10.7 Gy (p = 0.006); spine: Dmax, 42.4 Gy vs 46.4 Gy (p = 0.003)]. With a median follow-up of 18 months (6-33 months), the 1-year local control rate was 70% and the disease-free survival rate was 47%.

CONCLUSION

SMART reduces the incidence of severe oesophagitis and improves the whole dosimetric predictors of toxicity for the lung, heart and spine.

ADVANCES IN KNOWLEDGE

Our study shows that SMART optimizes the therapeutic ratio in the treatment of LANSCLC, opening a window for dose intensification.

Multivariable normal-tissue complication modeling of acute esophageal toxicity in advanced stage non-small cell lung cancer patients treated with intensity-modulated (chemo-)radiotherapy

BACKGROUND AND PURPOSE

The majority of normal-tissue complication probability (NTCP) models for acute esophageal toxicity (AET) in advanced stage non-small cell lung cancer (AS-NSCLC) patients treated with (chemo-)radiotherapy are based on three-dimensional conformal radiotherapy (3D-CRT). Due to distinct dosimetric characteristics of intensity-modulated radiation therapy (IMRT), 3D-CRT based models need revision. We established a multivariable NTCP model for AET in 149 AS-NSCLC patients undergoing IMRT.

MATERIALS AND METHODS

An established model selection procedure was used to develop an NTCP model for Grade ⩾2 AET (53 patients) including clinical and esophageal dose-volume histogram parameters.

RESULTS

The NTCP model predicted an increased risk of Grade ⩾2 AET in case of: concurrent chemoradiotherapy (CCR) [adjusted odds ratio (OR) 14.08, 95% confidence interval (CI) 4.70-42.19; p<0.001], increasing mean esophageal dose [Dmean; OR 1.12 per Gy increase, 95% CI 1.06-1.19; p<0.001], female patients (OR 3.33, 95% CI 1.36-8.17; p=0.008), and ⩾cT3 (OR 2.7, 95% CI 1.12-6.50; p=0.026). The AUC was 0.82 and the model showed good calibration.

CONCLUSIONS

A multivariable NTCP model including CCR, Dmean, clinical tumor stage and gender predicts Grade ⩾2 AET after IMRT for AS-NSCLC. Prior to clinical introduction, the model needs validation in an independent patient cohort.

Pitfalls and Challenges to Consider before Setting up a Lung Cancer Intensity-modulated Radiotherapy Service: A Review of the Reported Clinical Experience

Intensity-modulated radiotherapy (IMRT) is being increasingly used for the treatment of non-small cell lung cancer (NSCLC), despite the absence of published randomised controlled trials. Planning studies and retrospective series have shown a decrease in known predictors of lung toxicity (V20 and mean lung dose) and the maximum spinal cord dose. Potential dosimetric advantages, accessibility of technology, a desire to escalate dose or a need to meet normal organ dose constraints are some of the factors recognised as supporting the use of IMRT. However, IMRT may not be appropriate for all patients being treated with radical radiotherapy. Unique problems with using IMRT for NSCLC include organ and tumour motion because of breathing and the potential toxicity from low doses of radiotherapy to larger amounts of lung tissue. Caution should be exercised as there is a paucity of prospective data regarding the efficacy and safety of IMRT in lung cancer when compared with three-dimensional conformal radiotherapy and IMRT data from other cancer sites should not be extrapolated. This review looks at the use of IMRT in NSCLC, addresses the challenges and highlights the potential benefits of using this complex radiotherapy technique.

Incidence and predictors of severe acute esophagitis and subsequent esophageal stricture in patients treated with accelerated hyperfractionated chemoradiation for limited-stage small cell lung cancer

PURPOSE

Clinical and dosimetric predictors of severe (grade 3 or greater) acute esophageal toxicity and subsequent esophageal dilation were explored in patients with limited-stage small cell lung cancer treated with accelerated hyperfractionated chemoradiation.

METHODS AND MATERIALS

A total of 130 patients were identified who were treated to 45 Gy in 1.5-Gy twice-daily fractions with concurrent platinum-based chemotherapy between 2000 and 2009. Data on clinical, disease-related, and treatment-related variables were collected. Patients with percutaneous endoscopic gastrostomy tube insertion or intravenous hydration because of poor oral intake were designated as having acute grade 3 esophagitis. Univariate and multivariate analyses that associated treatment characteristics with esophagitis were assessed via logistic regression, and optimal cut points were identified with recursive partitioning analysis.

RESULTS

Twenty-five patients developed severe acute esophagitis, at a rate of 26% (18/69) in patients treated with earlier 3-dimensional conformal radiation therapy techniques and 11.5% (7/61) in patients treated with intensity modulated radiation therapy techniques and omission of elective nodal irradiation. The incidence of esophageal stricture was 6% overall (8 of 128 eligible) but 26% (6/23) among those who experienced prior grade 3 acute esophagitis and 2% (2/105) among those with acute esophagitis less than or equal to grade 2. Significant multivariate predictors of acute esophagitis were mean dose and volume of esophagus receiving at least 5% to 35% of the prescribed dose (V5 to V40). Patients with V5 ≥ 74% had a 44.4% risk of severe acute esophagitis (12/27) versus 12.6% (13/103) among those with V5 < 74%. V45 was the only dosimetric predictor for esophageal stricture, with 13.7% of patients in whom V45 was ≥37.5% requiring subsequent dilation.

CONCLUSIONS

Modern radiation techniques are associated with a lower frequency of severe acute esophagitis than previous paradigms. The proportion of esophagus receiving low- to moderate-range doses (mean, V5 through V40) predicts acute esophagitis, whereas the proportion of esophagus that receives high doses (V45) predicts the development of esophageal stricture that requires dilation. Patients who develop grade 3 acute esophagitis are at significant risk for subsequent esophageal stricture, whereas those with acute esophagitis of grade 2 or less display minimal risk.

Predictive SNPs for radiation-induced damage in lung cancer patients with radiotherapy: a potential strategy to individualize treatment

In the treatment of lung cancer, radiotherapy has become one of the most important therapies, despite its sometimes unpredictable side effects. As such, identifying lung cancer patients who are at high risk of developing severe radiation-induced damage (mainly radiation pneumonitis and radiation-induced esophageal toxicity) and applying effect intervention or monitoring techniques are important. Although human diversity to a certain amount is explained by clinical and dosimetric factors, the presence of specific genetic determinants also influences the occurrence of radiation-induced damage. Here we summarize the data on mechanisms of radiation pneumonitis and radiation-induced esophageal toxicity supporting the involvement of variances of genes in the evolution of radiation-induced damage. Furthermore, the available evidence from current clinical studies of genetic polymorphisms for the prediction of radiation pneumonitis and radiation-induced esophageal toxicity is discussed. Eventually, this may help to truly individualize radiotherapy, using a personal genetic profile of the most relevant genes for each lung cancer patient.

Improving target coverage and organ-at-risk sparing in intensity-modulated radiotherapy for cervical oesophageal cancer using a simple optimisation method

PURPOSE

To assess the performance of a simple optimisation method for improving target coverage and organ-at-risk (OAR) sparing in intensity-modulated radiotherapy (IMRT) for cervical oesophageal cancer.

METHODS

For 20 selected patients, clinically acceptable original IMRT plans (Original plans) were created, and two optimisation methods were adopted to improve the plans: 1) a base dose function (BDF)-based method, in which the treatment plans were re-optimised based on the original plans, and 2) a dose-controlling structure (DCS)-based method, in which the original plans were re-optimised by assigning additional constraints for hot and cold spots. The Original, BDF-based and DCS-based plans were compared with regard to target dose homogeneity, conformity, OAR sparing, planning time and monitor units (MUs). Dosimetric verifications were performed and delivery times were recorded for the BDF-based and DCS-based plans.

RESULTS

The BDF-based plans provided significantly superior dose homogeneity and conformity compared with both the DCS-based and Original plans. The BDF-based method further reduced the doses delivered to the OARs by approximately 1-3%. The re-optimisation time was reduced by approximately 28%, but the MUs and delivery time were slightly increased. All verification tests were passed and no significant differences were found.

CONCLUSION

The BDF-based method for the optimisation of IMRT for cervical oesophageal cancer can achieve significantly better dose distributions with better planning efficiency at the expense of slightly more MUs.

Risk factors of radiation-induced acute esophagitis in non-small cell lung cancer patients treated with concomitant chemoradiotherapy

Background

To analyze the clinical and dosimetric risk factors of acute esophagitis (AE) in non-small-cell lung cancer (NSCLC) patients treated with concomitant chemoradiotherapy.

Methods

Seventy-six NSCLC patients treated with concomitant chemoradiotherapy were retrospectively analyzed. Forty-one patients received concomitant chemoradiotherapy with vinorelbine/cisplatin (VC), 35 with docetaxel/cisplatin (DC). AE was graded according to criteria of the Radiation Therapy Oncology Group (RTOG). The following clinical and dosimetric parameters were analyzed: gender, age, clinical stage, Karnofsky performance status (KPS), pretreatment weight loss, concomitant chemotherapy agents (CCA) (VC vs. DC), percentage of esophagus volume treated to ≥20 (V20), ≥30 (V30), ≥40 (V40), ≥50 (V50) and ≥60 Gy (V60), and the maximum (Dmax) and mean doses (Dmean) delivered to esophagus. Univariate and multivariate logistic regression analysis were used to test the association between the different factors and AE.

Results

Seventy patients developed AE (Grade 1, 19 patients; Grade 2, 36 patients; and Grade 3, 15 patients). By multivariate logistic regression analysis, V40 was the only statistically significant factor associated with Grade ≥2 AE (p<0.001, OR = 1.159). A V40 of <23% had a 33.3% (10/30) risk of Grade ≥2 AE, which increased to 89.1% (41/46) with a V40 of ≥23% (p<0.001). CCA (p =0.01; OR = 9.686) and V50 (p<0.001; OR = 1.122) were most significantly correlated with grade 3 AE. A V50 of <26.5% had a 6.7% (3/45) risk of Grade 3 AE, which increased to 38.7% (12/31) with a V50 of ≥26.5% (p = 0.001). On the linear regression analysis, V50 and CCA were significant independent factors affecting AE duration. Patients who received concomitant chemotherapy with VC had a decreased risk of grade 3 AE and shorter duration compared with DC.

Conclusions

Concomitant chemotherapy agents have potential influence on AE. Concomitant chemotherapy with VC led to lower risk of AE compared with that using DC. V40 and V50 of esophagus can predict grade ≥2 and ≥3 AE, respectively.

Multiple comparisons permutation test for image based data mining in radiotherapy

Comparing incidental dose distributions (i.e. images) of patients with different outcomes is a straightforward way to explore dose-response hypotheses in radiotherapy. In this paper, we introduced a permutation test that compares images, such as dose distributions from radiotherapy, while tackling the multiple comparisons problem. A test statistic T_max was proposed that summarizes the differences between the images into a single value and a permutation procedure was employed to compute the adjusted p-value. We demonstrated the method in two retrospective studies: a prostate study that relates 3D dose distributions to failure, and an esophagus study that relates 2D surface dose distributions of the esophagus to acute esophagus toxicity. As a result, we were able to identify suspicious regions that are significantly associated with failure (prostate study) or toxicity (esophagus study). Permutation testing allows direct comparison of images from different patient categories and is a useful tool for data mining in radiotherapy.

[Helical tomotherapy in the treatment of malignant pleural mesothelioma: The impact of low doses on pulmonary and oesophageal toxicity]

PURPOSE

To evaluate the adjuvant treatment of malignant pleural mesothelioma by helical tomotherapy and the impact of low doses on esophageal and pulmonary toxicity.

PATIENTS AND METHODS

Between June 2007 and May 2011, 29 patients diagnosed with malignant pleural mesothelioma received adjuvant radiotherapy by helical tomotherapy. The median age was 63 years (34-72). Histologically, 83 % of patients had epithelioid malignant pleural mesothelioma. Clinically, 45 % of patients were T3 and 55 % N0. Eighty six percent of the patients were treated by extrapleural pneumonectomy and 35 % received neoadjuvant chemotherapy with platinum and pemetrexed. The median dose in the pneumonectomy cavity was 50Gy at 2Gy/fraction.

RESULTS

The mean follow-up was 2.3 years after diagnosis. Overall survival at 1 and 2 years was 65 and 36 % respectively. The median survival from diagnosis was 18 months. Median lung volumes receiving 2, 5, 10, 13, 15 and 20Gy (V2, V5, V10, V13, V15 and V20) were 100, 98, 52, 36, 19 and 5 %. The median of the mean remaining lung dose was 11Gy. Two patients died of pulmonary complications, three patients had grade 3 lung toxicity, while esophageal grade 3-4 toxicity was observed in three other patients. No significant impact of clinical characteristics and dosimetric parameters were found on pulmonary toxicity, however a V10≥50 %, a V15≥15 % and mean lung dose of 10Gy or more had a tendency to be predictive of pulmonary toxicity (P<0.1). Moreover, in our analysis, the mean lung dose seems to have a significant impact on esophageal toxicity (P=0.03) as well as low doses to the controlateral lung: V5, V10 and V13 (P<0.05).

CONCLUSION

Helical tomotherapy is a promising technique in the multimodality treatment of malignant pleural mesothelioma. Low doses received by the contralateral lung appear to be the limiting factor. A dosimetric comparison with volumetric modulated arctherapy techniques would be interesting in this setting.