Analysis of acute radiation-induced esophagitis in non-small-cell lung cancer patients using the Lyman NTCP model

Dosimetric predictors and Lyman normal tissue complication probability model of hematological toxicity in cervical cancer patients with treated with pelvic irradiation

PURPOSE

To identify dosimetric parameters associated with acute hematological toxicity (HT) and identify the corresponding normal tissue complication probability (NTCP) model in cervical cancer patients receiving helical tomotherapy (Tomo) or fixed-field intensity-modulated radiation therapy (ff-IMRT) in combination with chemotherapy, that is, concurrent chemoradiotherapy (CCRT) using the Lyman-Kutcher-Burman normal tissue complication probability (LKB-NTCP) model.

METHODS

Data were collected from 232 cervical cancer patients who received Tomo or ff-IMRT from 2015 to 2018. The pelvic bone marrow (PBM) (including the ilium, pubes, ischia, acetabula, proximal femora, and lumbosacral spine) was contoured from the superior boundary (usually the lumbar 5 vertebra) of the planning target volume (PTV) to the proximal end of the femoral head (the lower edge of the ischial tubercle). The parameters of the LKB model predicting ≥grade 2 hematological toxicity (Radiation Therapy Oncology Group [RTOG] grading criteria) (TD50 (1), m, and n) were determined using maximum likelihood analyses. Univariate and multivariate logistic regression analyses were used to identify correlations between dose-volume parameters and the clinical factors of HT.

RESULTS

In total, 212 (91.37%) patients experienced ≥grade 2 hematological toxicity. The fitted normal tissue complication probability model parameters were TD50 (1) = 38.90 Gy (95%CI, [36.94, 40.96]), m = 0.13 (95%CI [0.12, 0.16]), and n = 0.04 (95%CI [0.02, 0.05]). Per the univariate analysis, the NTCP (the use of LKB-NTCP with the set of model parameters found, p = 0.023), maximal PBM dose (p = 0.01), mean PBM dose (p = 0.021), radiation dose (p = 0.001), and V16-53 (p < 0. 05) were associated with ≥grade 2 HT. The NTCP (the use of LKB-NTCP with the set of model parameters found, p = 0.023; AUC = 0.87), V16, V17, and V18 ≥ 79.65%, 75.68%, and 72.65%, respectively (p < 0.01, AUC = 0.66∼0.68), V35 and V36 ≥ 30.35% and 28.56%, respectively (p < 0.05; AUC = 0.71), and V47 ≥ 13.43% (p = 0.045; AUC = 0.80) were significant predictors of ≥grade 2 hematological toxicity from the multivariate logistic regression analysis.

CONCLUSIONS

The volume of the PBM of patients treated with concurrent chemoradiotherapy and subjected to both low-dose (V16-18 ) and high-dose (V35,36 and V47 ) irradiation was associated with hematological toxicity, depending on the fractional volumes receiving the variable degree of dosage. The NTCP were stronger predictors of toxicity than V16-18 , V35, 36 , and V47 . Hence, avoiding radiation hot spots on the PBM could reduce the incidence of severe HT.

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.

Lyman-Kutcher-Burman normal tissue complication probability modeling for radiation-induced esophagitis in non-small cell lung cancer patients receiving proton radiotherapy

PURPOSE

To develop and test an Lyman-Kutcher-Burman (LKB) normal tissue complication probability (NTCP) model to predict radiation-induced esophagitis (RE) in non-small cell lung cancer (NSCLC) patients receiving passive-scattering proton therapy (PSPT).

MATERIAL AND METHODS

We retrospectively reviewed 328 NSCLC patients receiving PSPT at our institution. Esophagitis severity was graded by physicians according to the Common Toxicity Criteria for Adverse Events version 3.0, and the primary endpoint was grade ≥2 RE within 6 months from the first treatment. LKB model parameters (n, m, and TD₅₀) were determined using maximum likelihood estimation. Overall performance of the model was quantified by Nagelkerke's R² and the scaled Brier score. Discriminative ability was evaluated using the area under the receiver operating curve (AUC), and calibration was assessed with the Hosmer-Lemeshow goodness-of-fit test. Bootstrap internal validation was performed to assess the model uncertainty and generalizability.

RESULTS

Grade 2-3 RE was observed in 136 (41.5%) patients, and no grade 4-5 RE was reported. The optimal LKB parameters were: n = 0.24, m = 0.51, and TD₅₀ = 44.83 Gy (relative biological effectiveness). The optimism-corrected AUC was 0.783, and the Hosmer-Lemeshow test showed significant agreement between predicted and observed morbidity. Bootstrap validation verified that the model was robust to similar future populations.

CONCLUSION

Our LKB NTCP model to predict grade ≥2 RE in NSCLC patients who received PSPT showed good predictive performance and robustness to similar future populations, and a smaller volume effect than the previously observed in photon-treated populations. External validation of the model is warranted.

Analysis of Hepatitis B Virus Reactivation After Radiotherapy in Patients With Hepatocellular Carcinoma Using the Lyman NTCP Model

Purpose:

To analyze the correlation of hepatitis B virus reactivation with patient-related and treatment-related dose–volume factors and to describe the feasibility of hepatitis B virus reactivation analyzed by a normal tissue complication probability model for patients with hepatocellular carcinoma treated with radiotherapy.

Materials and Methods:

Ninety patients with hepatitis B virus-related hepatocellular carcinoma treated with radiotherapy were enrolled in this retrospective study and were followed from June 2009 to December 2015. Of the 90 patients, 78 had received conventional fractionation radiotherapy to a mean dose of 39.6 to 50.4 Gy and 12 patients were scheduled to receive hypofractionation. The physical doses were converted into 2 Gy equivalents for analysis. The parameters, TD₅₀ (1), n, and m, of the Lyman-Kutcher-Burman normal tissue complication probability model were derived using maximum likelihood estimation. Bootstrap and leave-one-out were employed to against model overfitting and improve the model stability.

Results:

Radiation-induced liver diseases were 17.8%, hepatitis B virus reactivation was 22.2%, and hepatitis B virus reactivation-induced hepatitis was 21.1%, respectively. In multivariate analysis, the V_5Gy was associated with hepatitis B virus reactivation; TD₅₀ (1), m, and n were 32.3, 0.55, and 0.71 Gy, respectively, for hepatitis B virus reactivation. Bootstrap and leave-one-out results showed that the hepatitis B virus parameter fits were extremely robust.

Conclusion:

A Lyman-Kutcher-Burman normal tissue complication probability model has been established to predict hepatitis B virus reactivation for patients with hepatocellular carcinoma who received radiotherapy.

A prospective, three-arm, randomized trial of EGCG for preventing radiation-induced esophagitis in lung cancer patients receiving radiotherapy

BACKGROUND AND PURPOSE

This trial investigated whether epigallocatechin-3-gallate (EGCG), a radioprotector, could be effective in the prevention and treatment of acute radiation-induced esophagitis (ARIE).

METHODS AND MATERIALS

This is a phase II study of EGCG combined with chemoradiation in unresectable stage III non-small-cell lung cancer or limited stage small cell lung cancer. Patients were randomized into a prophylactic EGCG group (arm A), a therapeutic EGCG group after the occurrence of esophagitis (arm B) or conventional therapy group (arm C). Esophagitis grades, pain and dysphagia scores were recorded weekly. Adjusted esophagitis index (AEI), pain index (API) and dysphagia index (ADI) were calculated to reflect changes in esophagitis grade, pain score and dysphagia score throughout treatment.

RESULTS

A total of 83 patients were eligible for toxicity analysis (arm A vs arm B vs arm C: N = 28:27:28). There was no significant difference in the baseline characteristics among three arms of the patients. The difference in the maximum esophagitis grade among three groups was statistically significant (P = 0.004). The maximum ARIE for patients with EGCG was significantly lower than for those with conventional therapy. The mean AEI of arm A was lower than that of arm B, while the mean AEI of arm C was the highest (arm A vs arm B, P = 0.028; arm B vs arm C, P = 0.002). Furthermore, API and ADI were significantly lower in patients receiving EGCG than in conventionally treated patients.

CONCLUSION

The application of EGCG could effectively alleviate acute radiation esophagitis in advanced lung cancer without obvious side effects. Prophylactic application of EGCG had a slight advantage over therapeutic use in treatment of acute esophagitis.

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.

Differences in Normal Tissue Response in the Esophagus Between Proton and Photon Radiation Therapy for Non-Small Cell Lung Cancer Using In Vivo Imaging Biomarkers

PURPOSE

To determine whether there exists any significant difference in normal tissue toxicity between intensity modulated radiation therapy (IMRT) or proton therapy for the treatment of non-small cell lung cancer.

METHODS AND MATERIALS

A total of 134 study patients (n=49 treated with proton therapy, n=85 with IMRT) treated in a randomized trial had a previously validated esophageal toxicity imaging biomarker, esophageal expansion, quantified during radiation therapy, as well as esophagitis grade (Common Terminology Criteria for Adverse Events version 3.0), on a weekly basis during treatment. Differences between the 2 modalities were statically analyzed using the imaging biomarker metric value (Kruskal-Wallis analysis of variance), as well as the incidence and severity of esophagitis grade (χ² and Fisher exact tests, respectively). The dose-response of the imaging biomarker was also compared between modalities using esophageal equivalent uniform dose, as well as delivered dose to an isotropic esophageal subvolume.

RESULTS

No statistically significant difference in the distribution of esophagitis grade, the incidence of grade ≥3 esophagitis (15 and 11 patients treated with IMRT and proton therapy, respectively), or the esophageal expansion imaging biomarker between cohorts (P>.05) was found. The distribution of imaging biomarker metric values had similar distributions between treatment arms, despite a slightly higher dose volume in the proton arm (P>.05). Imaging biomarker dose-response was similar between modalities for dose quantified as esophageal equivalent uniform dose and delivered esophageal subvolume dose. Regardless of treatment modality, there was high variability in imaging biomarker response, as well as esophagitis grade, for similar esophageal doses between patients.

CONCLUSIONS

There was no significant difference in esophageal toxicity from either proton- or photon-based radiation therapy as quantified by esophagitis grade or the esophageal expansion imaging biomarker.

Radiomic analysis in contrast-enhanced CT: predict treatment response to chemoradiotherapy in esophageal carcinoma

Objectives

To investigate the capability of computed-tomography (CT) radiomic features to predict the therapeutic response of Esophageal Carcinoma (EC) to chemoradiotherapy (CRT).

Methods

Pretreatment contrast-enhanced CT images of 49 EC patients (33 responders, 16 nonresponders) who received with CRT were retrospectively analyzed. The region of tumor was contoured by two radiologists. A total of 214 features were extracted from the tumor region. Kruskal-Wallis test and receiver operating characteristic (ROC) analysis were performed to evaluate the capability of each feature on treatment response classification. Support vector machine (SVM) and artificial neural network (ANN) algorithms were used to build models for prediction of the treatment response. The statistical difference between the performances of the models was assessed using McNemar's test.

Results

Radiomic-based classification showed significance in differentiating responders from nonresponders. Five features were found to discriminate nonresponders from responders (AUCs from 0.686 to 0.727). Considering these features, two features (Histogram2D_skewness: P = 0.015. Histogram2D_kurtosis: P = 0.039) were significant for differentiating SDs (stable disease) from PRs (partial response) and one feature (Histogram2D_skewness: P = 0.027) for differentiating SDs from CRs (complete response). Both classifiers showed potential in predicting the treatment response with higher accuracy (ANN: 0.972, SVM: 0.891). No statistically significant difference was observed in the performance of the two classifiers (P = 0.250).

Conclusions

CT-based radiomic features can be used as imaging biomarkers to predict tumor response to CRT in EC patients.

An integrated strategy of biological and physical constraints in biological optimization for cervical carcinoma

Background

For cervical carcinoma cases, this study aimed to evaluate the quality of intensity-modulated radiation therapy (IMRT) plans optimized by biological constraints. Furthermore, a new integrated strategy in biological planning module was proposed and verified.

Methods

Twenty patients of advanced stage cervical carcinoma were enrolled in this study. For each patient, dose volume optimization (DVO), biological model optimization (BMO) and integrated strategy optimization (ISO) plans were created using same treatment parameters. Different biological models were also used for organ at risk (OAR) in BMO plans, which include the LKB and Poisson models. Next, BMO plans were compared with their corresponding DVO plans, in order to evaluate BMO plan quality. ISO plans were also compared with DVO and BMO plans, in order to verify the performance of the integrated strategy.

Results

BMO plans produced slightly inhomogeneity and less coverage of planning target volume (PTV) (V95=96.79, HI = 0.10: p < 0.01). However, the tumor control probability (TCP) value, both from DVO and BMO plans, were comparable. For the OARs, BMO plans produced lower normal tissue complication probability (NTCP) of rectum (NTCP = 0.11) and bladder (NTCP = 0.14) than in the corresponding DVO plans (NTCP = 0.19 and 0.18 for rectum and bladder; p < 0.01 for rectum and p = 0.03 for bladder). V95, D98, CI and HI values that were produced by ISO plans (V95 = 98.31, D98 = 54.18Gy, CI = 0.76, HI = 0.09) were greatly better than BMO plans (V95 = 96.79, D98 = 53.42Gy, CI = 0.71, HI = 0.10) with significant differences. Furthermore, ISO plans produced lower NTCP values of rectum (NTCP = 0.14) and bladder (NTCP = 0.16) than DVO plans (NTCP = 0.19 and 0.18 for rectum and bladder, respectively) with significant differences.

Conclusions

BMO plans produced lower NTCP values of OARs compared to DVO plans for cervical carcinoma cases, and resulted in slightly less target coverage and homogeneity. The integrated strategy, proposed in this study, could improve the coverage, conformity and homogeneity of PTV greater than the BMO plans, as well as reduce the NTCP values of OARs greater than the DVO plans.

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.

The benefit of using bladder sub-volume equivalent uniform dose constraints in prostate intensity-modulated radiotherapy planning

Background

To assess the benefits of bladder wall sub-volume equivalent uniform dose (EUD) constraints in prostate cancer intensity-modulated radiotherapy (IMRT) planning.

Methods

Two IMRT plans, with and without EUD constraints on the bladder wall, were generated using beams that deliver 80 Gy to the prostate and 46 Gy to the seminal vesicles and were compared in 53 prostate cancer patients. The bladder wall was defined as the volume between the external manually delineated wall and a contraction of 7 mm apart from it. The bladder wall was then separated into two parts: the internal-bladder wall (bla-in) represented by the portion of the bladder wall that intersected with the planning target volume (PTV) plus 5 mm extension; the external-bladder wall (bla-ex) represented by the remaining part of the bladder wall. In the IMRT plan with EUD constraints, the values of “a” parameter for the EUD models were 10.0 for bla-in and 2.3 for bla-ex. The plans with and without EUD constraints were compared in terms of dose–volume histograms, 5-year bladder and rectum normal tissue complication probability values, as well as tumor control probability (TCP) values.

Results

The use of bladder sub-volume EUD constraints decreased both the doses to the bladder wall (V₇₀: 22.76% vs 19.65%, D_mean: 39.82 Gy vs 35.45 Gy) and the 5-year bladder complication probabilities (≥LENT/SOMA Grade 2: 20.35% vs 17.96%; bladder bleeding: 10.63% vs 8.64%). The doses to the rectum wall and the rectum complication probabilities were also slightly decreased by the EUD constraints compared to physical constraints only. The minimal dose and the V_76Gy of PTV_prostate were, however, slightly decreased by EUD optimization, nevertheless without significant difference in TCP values between the two plans, and the PTV parameters finally respected the Groupe d’Etude des Tumeurs Uro-Génitales recommendations.

Conclusion

Separating the bladder wall into two parts with appropriate EUD optimization may reduce bladder toxicity in prostate IMRT. Combining biological constraints with physical constraints in the organs at risk at the inverse planning step of IMRT may improve the dose distribution.

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.

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.

Contrasting analytical and data-driven frameworks for radiogenomic modeling of normal tissue toxicities in prostate cancer

BACKGROUND AND PURPOSE

We explore analytical and data-driven approaches to investigate the integration of genetic variations (single nucleotide polymorphisms [SNPs] and copy number variations [CNVs]) with dosimetric and clinical variables in modeling radiation-induced rectal bleeding (RB) and erectile dysfunction (ED) in prostate cancer patients.

MATERIALS AND METHODS

Sixty-two patients who underwent curative hypofractionated radiotherapy (66 Gy in 22 fractions) between 2002 and 2010 were retrospectively genotyped for CNV and SNP rs5489 in the xrcc1 DNA repair gene. Fifty-four patients had full dosimetric profiles. Two parallel modeling approaches were compared to assess the risk of severe RB (Grade⩾3) and ED (Grade⩾1); Maximum likelihood estimated generalized Lyman-Kutcher-Burman (LKB) and logistic regression. Statistical resampling based on cross-validation was used to evaluate model predictive power and generalizability to unseen data.

RESULTS

Integration of biological variables xrcc1 CNV and SNP improved the fit of the RB and ED analytical and data-driven models. Cross-validation of the generalized LKB models yielded increases in classification performance of 27.4% for RB and 14.6% for ED when xrcc1 CNV and SNP were included, respectively. Biological variables added to logistic regression modeling improved classification performance over standard dosimetric models by 33.5% for RB and 21.2% for ED models.

CONCLUSION

As a proof-of-concept, we demonstrated that the combination of genetic and dosimetric variables can provide significant improvement in NTCP prediction using analytical and data-driven approaches. The improvement in prediction performance was more pronounced in the data driven approaches. Moreover, we have shown that CNVs, in addition to SNPs, may be useful structural genetic variants in predicting radiation toxicities.

How does four-dimensional computed tomography spare normal tissues in non-small cell lung cancer radiotherapy by defining internal target volume?

BACKGROUND

To investigate how the four-dimensional computed tomography (4DCT) technique spares normal tissues in non-small cell lung cancer (NSCLC) radiotherapy by defining individualized internal target volume (ITV).

MATERIALS AND METHODS

Gross tumor volume (GTV) and clinical target volume (CTV) were contoured on all 10 respiratory phases of 4DCT scans in 10 patients with peripheral NSCLC. Both 3D and 4D treatment plans were performed for each patient using planning target volume (PTV)3D (derived from a single CTV plus conventional margins) and PTV4D (derived from 4D internal target volume, which included all 10 CTVs plus setup margins). Dose volume histogram and normal tissue complication probability (NTCP) values were compared for the lung, heart, and spinal cord between 3D and 4D treatment plans.

RESULTS

The average PTV of the 4D (127.56 ± 70.79) was less than the 3D plans (147.65 ± 76.89). The 4D spared more surrounding normal tissues than the 3D plans, especially in the lung. Compared with 3D plans, V5, V10, V20 and V30 of the total lung decreased from 41.25%, 37.75%, 24.25%, 17.00% to 38.13%, 33.00%, 21.25%, 15.13%, respectively. Without increasing the NTCP of the lung significantly, the 4D plans allowed us to increase the average prescription dose from 60 Gy to 66.00 ± 4.62 Gy.

CONCLUSIONS

4DCT based plans can reduce the target volumes, spare more normal tissues, and allow dose escalation compared with 3D plans in NSCLC radiotherapy.

Acute phase response before treatment predicts radiation esophagitis in non-small cell lung cancer

BACKGROUND AND PURPOSE

Radiation esophagitis (RE) represents an inflammatory reaction to radiation therapy (RT). We hypothesized that aspects of the physiologic acute phase response (APR) predicts RE.

MATERIAL AND METHODS

We retrospectively analyzed 285 patients with non-small cell lung cancer (NSCLC) treated with definitive radiation. The primary analysis was the association of pretreatment lab values reflective of the APR with symptomatic (grade ⩾ 2) RE. Univariate and multivariate odds ratios (ORs) were calculated to test associations of clinical and pretreatment lab values with RE. Optimal cutpoints and multivariable risk stratification groupings were determined via recursive partitioning analysis.

RESULTS

Pretreatment platelet counts were higher and hemoglobin levels lower in patients who developed RE (P<0.05). Based on these two pre-treatment risk factors, an APR score was defined as 0 (no risk factors), 1 (either risk factor), or 2 (both risk factors). APR score was significantly associated with RE in both univariate (OR = 2.3 for each point, 95% confidence interval [CI] 1.5-3.4, P = 0.001) and multivariate (OR = 2.1, 95% CI 1.3-3.4, P = 0.002) analyses.

CONCLUSIONS

The APR score may represent a novel metric to predict RE. However, pending validation in an independent dataset, caution is advised when interpreting these results given their retrospective and thus exploratory nature.

A phase I study of concurrent chemotherapy and thoracic radiotherapy with oral epigallocatechin-3-gallate protection in patients with locally advanced stage III non-small-cell lung cancer

BACKGROUND AND PURPOSE

Patients with unresectable stage III non-small-cell lung cancer receiving concurrent chemoradiotherapy often develop esophagitis that may lead to unplanned treatment interruptions, which may severely reduce rates of locoregional tumor control and survival. No effectivetreatment that would reduce the incidence and severity of this complication has been identified up to now. Although acceleration of normal tissue protection using epigallocatechin-3-gallate (EGCG) has been reported, its actual clinical practicability remains obscure.

METHODS AND MATERIALS

This is a phase I study of EGCG in combination with standard chemoradiation in surgically unresectable stage III non-small-cell lung cancer. Chemotherapy (cisplatin and etoposide) was given concurrently with radiation. EGCG solution was swallowed three times a day after the occurrence of grade 2 esophagitis at six concentration levels and dose escalation followed a standard phase I design. Esophageal toxicity and patient-reported pain was recorded weekly.

RESULTS

Twenty-four patients with AJCC stage IIIA (six) and IIIB (eighteen) completed the course of therapy. Twelve had squamous histology, ten adenocarcinoma, and two not specified. Patients were treated in six cohorts at six dose levels of EGCG. RT was not interrupted with a median dose of 64 Gy. There were no dose-limiting toxicities reported in all EGCG dosing tiers. Dramatic regression of esophagitis to grade 0/1 was observed in 22 of 24 patients, whereas grade 2 esophagitis persisted in 2 of 24 patients at the end of radiotherapy. The pain score was also reduced from a mean of 4.58 (N=24), 1.29 (N=24), 1.42 (N=24), 0.96 (N=23) to 1.13 (N=16) every week in turn.

CONCLUSION

We conclude that the oral administration of EGCG is feasible, safe and effective. The phase II recommended concentration is 440 μmol/L.

Acute radiation esophagitis caused by high-dose involved field radiotherapy with concurrent cisplatin and vinorelbine for stage III non-small cell lung cancer

Purpose of this study is to obtain dose-volume histogram (DVH) predictors and threshold values for radiation esophagitis caused by high-dose involved field radiotherapy (IFRT) with concurrent chemotherapy in patients with stage III non-small cell lung cancer (NSCLC). Thirty-two patients treated by 66 Gy/33 Fr, 72 Gy/36 Fr, and 78 Gy/39 Fr thoracic radiotherapy without elective nodal irradiation plus concurrent cisplatin and vinorelvine were reviewed. Acute radiation esophagitis was evaluated according to common terminology criteria for adverse events version 4.0, and correlations between grade 2 or worse radiation esophagitis and DVH parameters were investigated. Grade 0-1, 2, 3, and 4-5 of radiation esophagitis were seen in 11 (34.4%), 20 (62.5%), 1 (3.1%), and 0 (0%) of the patients, respectively. Multivariate analysis revealed that whole esophagus V35 is a predictor of radiation esophagitis (OR = 0.74 [95%CI; 0.60-0.91], p = 0.006). There is a significant difference (38.4% vs. 89.4%, p = 0.027) in the cumulative rates of acute esophagitis according to V35 values of more than 20% versus less. As compared with other factors concerning patient and tumor and treatment factors, V35 ≤ 20% of the esophagus was an independent predictor (HR 5 0.29 [95%CI; 0.09-0.85], p 5 0.025). In conclusion, whole esophagus V35 < 20% is proposed in high-dose IFRT with concurrent chemotherapy for stage III NSCLC patients.

[Esophageal toxicity of radiation therapy: clinical risk factors and management]

Acute radiation-induced esophagitis includes all clinical symptoms (odynophagia, dysphagia) occurring within 90 days after thoracic irradiation start. Its severity can be graded using RTOG and CTCAE scales. The clinical risk factors are: age, female gender, initial performance status, pre-therapeutic body mass index, pre-therapeutic dysphagia, tumoral and nodal stage, delivered dose, accelerated hyperfractionned radiotherapy, concomitant association of chemotherapy to radiotherapy and response to the treatment. The dosimetric parameters predictive of esophagitis are: mean dose, V(20Gy), V(30Gy), V(40Gy), V(45Gy) and V(50Gy). Amifostine is the only drug to have a proven radioprotective efficacy (evidence level C, ESMO recommendation grade III). The medical management of esophagitis associates a diet excluding irritant food, medication against gastroesophageal reflux, analgesic treatment according to the WHO scale and management of dehydration and denutrition by enteral feeding.