Patterns of CT lung injury and toxicity after stereotactic radiotherapy delivered with helical tomotherapy in early stage medically inoperable NSCLC

CT patterns and serial CT Changes in lung Cancer patients post stereotactic body radiotherapy (SBRT)

Background

To evaluate computed tomography (CT) patterns of post-SBRT lung injury in lung cancer and identify time points of serial CT changes.

Materials and methods

One hundred eighty-three tumors in 170 patients were evaluated on sequential CTs within 29 months (median). Frequencies of post-SBRT CT patterns and time points of initiation and duration were assessed. Duration of increase of primary lesion or surrounding injury without evidence of local recurrence and time to stabilization or local recurrence were evaluated.

Results

Post-SBRT CT patterns could overlap in the same patient and were nodule-like pattern (69%), consolidation with ground glass opacity (GGO) (41%), modified conventional pattern (39%), peribronchial/patchy consolidation (42%), patchy GGO (24%), diffuse consolidation (16%), “orbit sign” (21%), mass-like pattern (19%), scar-like pattern (15%) and diffuse GGO (3%). Patchy GGO started at 4 months post-SBRT. Peribronchial/patchy consolidation and consolidation with GGO started at 4 and 5 months respectively. Diffuse consolidation, diffuse GGO and orbit sign started at 5, 6 and 8 months respectively. Mass-like, modified conventional and scar-like pattern started at 8, 12 and 12 months respectively. Primary lesion (n = 11) or surrounding injury (n = 85) increased up to 13 months. Primary lesion (n = 119) or surrounding injury (n = 115) started to decrease at 4 and 9 months respectively. Time to stabilization was 20 months. The most common CT pattern at stabilization was modified conventional pattern (49%), scar-like pattern (23%) and mass-like pattern (12%). Local recurrence (n = 15) occurred at a median time of 18 months.

Conclusion

Different CT patterns of lung injury post-SBRT appear in predictable time points and have variable but predictable duration. Familiarity with these patterns and timeframes of appearance helps differentiate them from local recurrence.

Strategies to develop radiomics and machine learning models for lung cancer stage and histology prediction using small data samples

Predictive models based on radiomics and machine-learning (ML) need large and annotated datasets for training, often difficult to collect. We designed an operative pipeline for model training to exploit data already available to the scientific community. The aim of this work was to explore the capability of radiomic features in predicting tumor histology and stage in patients with non-small cell lung cancer (NSCLC). We analyzed the radiotherapy planning thoracic CT scans of a proprietary sample of 47 subjects (L-RT) and integrated this dataset with a publicly available set of 130 patients from the MAASTRO NSCLC collection (Lung1). We implemented intra- and inter-sample cross-validation strategies (CV) for evaluating the ML predictive model performances with not so large datasets. We carried out two classification tasks: histology classification (3 classes) and overall stage classification (two classes: stage I and II). In the first task, the best performance was obtained by a Random Forest classifier, once the analysis has been restricted to stage I and II tumors of the Lung1 and L-RT merged dataset (AUC = 0.72 ± 0.11). For the overall stage classification, the best results were obtained when training on Lung1 and testing of L-RT dataset (AUC = 0.72 ± 0.04 for Random Forest and AUC = 0.84 ± 0.03 for linear-kernel Support Vector Machine). According to the classification task to be accomplished and to the heterogeneity of the available dataset(s), different CV strategies have to be explored and compared to make a robust assessment of the potential of a predictive model based on radiomics and ML.

Comparison of Radiation Pneumonitis in Lung Cancer Patients Treated with HT versus IMRT and Circulating Lymphocyte Subsets as Predicting Risk Factors

Purpose

We sought to compare the symptomatic radiation pneumonitis (RP) in lung cancer patients treated with helical tomotherapy (HT) versus intensity-modulated radiotherapy (IMRT), and examine the predictive value of circulating lymphocyte subsets affecting the occurrence of RP.

Patients and Methods

Circulating lymphocyte subsets, clinical characteristics, dosimetric parameters and pulmonary function were collected from 130 lung cancer patients treated with HT (n = 53) or IMRT (n = 77) from 2016 through 2020. Symptomatic RP was compared between groups. Binary logistic regression was used to identify predictors of RP.

Results

The IMRT group had larger planning target volume (319.9 vs 240.8 cc, P = 0.041); more ECOG performance status 0–1 (96.1% vs 79.2%, P = 0.002); more stage III–IV disease (94.8% vs 37.6%, P = 0.028); and more combined systemic therapy (85.7% vs 69.8%, P = 0.022). Grade ≥2 RP were comparable between IMRT and HT groups (16.9% vs 15.1%, P = 0.785). For stage III–IV disease, IMRT was associated with lower lung V10 (31.9% vs 35.8%, P = 0.047) and lower incidence of grade 5 RP (0% vs 9.1%, P = 0.018). All lymphocyte subsets reduced after radiotherapy. The decrease degree of total T cell count and CD4⁺ T cell count were larger after IMRT than HT (P = 0.043, P = 0.021). In univariate analysis, the smoking status, lower baseline FEV1, and higher total T cell count, higher CD8⁺ T cell count, lower total B cell count, lower CD4⁺/CD8⁺ ratio after radiotherapy were associated with the development of grade ≥2 RP. The higher CD8⁺T cell count after radiotherapy was the only risk factor associated with grade ≥2 RP in multivariable analysis (OR 1.003; 95% CI: 1.000–1.005; P = 0.044).

Conclusion

IMRT was associated with lower lung V10 and less grade 5 RP than HT for stage III–IV lung cancer. Higher CD8⁺ T cell count after radiotherapy was associated with an increased risk of RP. HT may better preserve total T cell and CD4⁺ T cell than IMRT.

Gamma Radiation-Induced Rib Necrosis and Stereotactic Radiosurgery Failure

Stereotactic radiosurgery, or SRS, uses focused beams of gamma radiation targeted to specific areas of the body and has been used for multiple forms of non-small cell lung cancer. In this article, the authors describe two incidental cases of osteonecrosis in patients who had previously undergone stereotactic radiosurgery with recurrence of tumor. While this is a known side effect of traditional radiation therapy, it has not been described in the context of stereotactic radiosurgery. Further, these lesions were immediately deep to a rib, which may have shielded the lesion, and led to SRS failure. Osteonecrosis of the rib is a rare clinical entity but has been found to occur with glucocorticoid use, bisphosphonates, radiation therapy, and radiofrequency ablation. In the authors' review of the literature on SRS for lung cancer and intrathoracic pathology, rib osteonecrosis was not described and has not been mentioned as a possible side effect. Patients who have undergone thoracic stereotactic radiotherapy may develop side effects of traditional radiotherapy. We identified two patients who developed rib osteonecrosis though that has not been previously described as an adverse effect of stereotactic radiotherapy. The patients described in this case did not have any radiographic evidence of disease on imaging, suggesting that further research is warranted on the diagnosis and management of this rare disease entity.

Left Ventricular Systolic Dysfunction Is a Possible Independent Risk Factor of Radiation Pneumonitis in Locally Advanced Lung Cancer Patients

Objectives: To assess the association between left ventricular (LV) systolic and diastolic dysfunction and grade ≥2 radiation pneumonitis (RP) for locally advanced lung cancer patients receiving definitive radiotherapy. Materials and Methods: A retrospective analysis was carried out for 260 lung cancer patients treated with definitive radiotherapy between 2015 and 2017. RP was evaluated according to Radiation Therapy Oncology Group (RTOG) toxicity criteria. Logistic regression analysis, 10-fold cross validation, and external validation were performed. The prediction model's discriminative performance was evaluated using the area under the receiver operating characteristic curve (AUC), and calibration of the model was assessed by the Hosmer-Lemeshow test and the calibration curve. Results: Within the first 6 months after radiotherapy, 70 patients (26.9%) developed grade ≥2 RP. Reduced left ventricular ejection fraction (LVEF) before radiotherapy was detected in 53 patients (20.4%). The odds ratio (OR) of developing RP for patients with LVEF <50% was 3.42 [p < 0.001, 95% confidence interval (CI), 1.85-6.32]. Multivariate analysis showed that forced expiratory volume in the first second/forced vital capacity (FEV1/FVC), LVEF, Eastern Cooperative Oncology Group (ECOG) performance status, chemotherapy, and mean lung dose (MLD) were significantly associated with grade ≥2 RP. The AUC of a model including the above five variables was 0.835 (95% CI, 0.778-0.891) on 10-fold cross validation and 0.742 (95% CI, 0.633-0.851) on the external validation set. The p-value for the Hosmer-Lemeshow test was 0.656 on 10-fold cross validation and 0.534 on the external validation set. Conclusion: LV systolic dysfunction is a possible independent risk factor for RP in locally advanced lung cancer patients receiving definitive radiotherapy.

Hypo-fractionated stereotactic radiation therapy for lung malignancies by means of helical tomotherapy: report of feasibility by a single-center experience

BACKGROUND

Several experiences in the literature report SBRT as an effective treatment option for medically inoperable early stage non-small cell lung cancer (NSCLC) and oligometastatic disease. The optimal fractionation schedules and total dose remain controversial. In this study, we evaluated the safety in terms of toxicity and efficacy of using of 8-10 fractions schedules with Helical Tomotherapy (HT) for primary and metastatic lung lesions.

METHODS

Between March 2014 and May 2016, a total of 39 patients (median age 72 years, range 26-91) were treated with HT-SBRT for malignant lung lesions: 22 patients with early stage NSCLC, 17 with oligometastases. Patients received 8-10 fractions with lower daily dose for central and ultracentral lesions. Treatment-related toxicity was evaluated using CTCAE v 4.0 scale. Local control (LC), overall survival (OS) and toxicity rates were prospectively collected.

RESULTS

Median duration of RT was 15 days (range 10-26 days) and no interruption occurred. With a median follow-up of 13 months (range 3-29), we reported one G2 pneumonitis (2.6%) and one G2 chest pain (2.6%); no ≥ G2 esophagitis was registered. Actuarial local control rate was 95.5% both at 12 and 24 months for early stage NSCLC and 92.9% both at 12 and 24 months for metastatic patients. OS rate was 94.4 and 92.3% at 1 year, and 94.4 and 83.9% at 2 years in primary and metastatic group, respectively.

CONCLUSIONS

The use of 8-10 fractions schedule HT-SBRT for lung malignancies results in high LC and OS rates with minimal toxicities reported.

No differences in radiological changes after 3D conformal vs VMAT-based stereotactic radiotherapy for early stage non-small cell lung cancer

OBJECTIVE

To compare patterns of acute and late radiological lung injury following either 3D conformal or image-guided volumetric modulated arc therapy stereotactic radiotherapy for Stage I non-small-cell lung cancer.

METHODS

We included 148 patients from a prospective mono-institutional stereotactic body radiation therapy (SBRT) series (time interval 2004-2014), treated with prescription BED_{10 Gy} (at 80%) in the range 100-120 Gy. The first 95 patients (2004-2010) were planned with 3D-CRT, with a stereotactic body frame. The second cohort (2010-2014) included 53 patients, planned with volumetric IMRT on a smaller planning target volume generated from a patient's specific internal target volume, with a frameless approach through cone-beam CT guidance. Acute and late radiological modifications were scored based on modified Kimura's and Koenig's classifications, respectively.

RESULTS

Median follow-up time was 20.5 months. The incidence of acute radiological changes was superimposable between the groups: increased density was observed in 68.4 and 64.2% of patients for 3D-CRT and VMAT, respectively, and patchy ground glass opacity in 23.7 and 24.5%, respectively; diffuse ground glass opacity was 2.6 vs 9.4%, respectively, and patchy consolidation 2.6 vs 1.9%, respectively. Late changes occurred in approximately 60% of patients: modified conventional pattern was the most frequent modification (25 vs 32.6%, respectively); other patterns were less common (mass-like 19.6 vs 17.4%, and scar-like 13 vs 10.9%, respectively).

CONCLUSION

Results of the present study indicate that the pattern of radiological lung changes following SBRT for peripheral early stage non-small-cell lung cancer is not influenced by the different techniques used for planning and delivery. Advances in knowledge: This comparative observational study shows that smaller margins, image guidance and most importantly dose distribution do not change the pattern of radiological injury after lung SBRT; the same scoring system can be used, and expected incidence is similar.

Constraints for symptomatic radiation pneumonitis of helical tomotherapy hypofractionated simultaneous multitarget radiotherapy for pulmonary metastasis from hepatocellular carcinoma

BACKGROUND AND PURPOSE

This study was aimed to identify the clinical and dosimetric parameters that predict symptomatic radiation pneumonitis (SRP, radiation pneumonitis≥2 grade) in patients with pulmonary metastasis from hepatocellular carcinoma (HCC) after helical tomotherapy (HT) hypofractionated simultaneous multitarget radiotherapy.

MATERIALS AND METHODS

62 patients with 407 pulmonary metastases from HCC were consecutively treated with HT. The median radiation dose was a 49.7Gy in 4.0Gy/fraction to 95% of the planning target volume (PTV). The associations between the clinical and dosimetric data and incidences of SRP were analyzed. The dose-pneumonitis relationship was analyzed based on Biologically Effective Dose (BED).

RESULTS

Univariate analysis showed that the gross tumor volume (GTV), PTV, median lung dose (MLD), the number of pulmonary metastatic lesions (NPML), and the percentage of non-target normal lung (NTNL) volume receiving more than a BED of 3-50Gy (V_BED3-50) were associated with SRP. Multivariate logistic regression analysis showed that V_BED20 and NPML were significant parameters (both P<0.001) CONCLUSIONS: Our findings indicated that SRP can be predicted with NPML>5 and V_BED20≥30.4% with the α/β ratio of 3Gy.

Treatment outcomes and patterns of radiologic appearance after hypofractionated image-guided radiotherapy delivered with helical tomotherapy (HHT) for lung tumours

OBJECTIVE

To evaluate treatment outcomes and patterns of CT lung injury after hypofractionated image-guided radiotherapy delivered with helical tomotherapy (HHT) in a series of inoperable lung lesions.

METHODS

68 patients who were medically inoperable (69 lesions) without evidence of viable extrathoracic disease were included. Dose prescription was driven by tumour location (hilar/pericentral vs peripheral) and/or target volume. 52% of the lesions received a biological equivalent dose (BED10) ≥100 Gy. Assessment of tumour response was based on the Response Evaluation Criteria in Solid Tumours 1.1 criteria coupled with fluorine-18 fludeoxyglucose/positron emission tomography-CT. Toxicity monitoring was focused on treatment-related pulmonary adverse events according to the Common Terminology Criteria for Adverse Events v. 4.0. Acute and late events were classified as radiation pneumonitis (RP) and radiation fibrosis (RF), respectively. Survival curves were calculated using the Kaplan-Meier method. Univariate and multivariate analyses of survival were performed using the Cox proportional hazards model.

RESULTS

After a median follow-up of 12 months (range, 3-31 months), no instances of ≥Grade 4 RP was documented, and clinically severe (Grade 3) RP occurred in 5.8% of the patients. 2 (3%) patients developed a late severe (≥Grade 3) symptomatic RF. No specific pattern of CT lung injury was demonstrated, in both acute and late settings. Median overall survival (OS) and progression-free survival (PFS) for the entire population were 30.8 and 14.1 months, respectively. At multivariate analysis (MVA), BED10 ≥ 100 Gy and KPS ≥ 90 emerged as significant prognostic factors for OS (p = 0.01 and p = 0.001, respectively), and BED10 ≥ 100 Gy for PFS (p = 0.02).

CONCLUSION

Our findings show that HHT adjusted for tumour location and/or target volume is an effective treatment with an acceptable toxicity profile in patients who are medically inoperable with lung tumours and is not associated with a specific pattern of lung injury. Therefore, it can represent a viable option when conventional stereotactic ablative radiotherapy facilities are not available. Advances in knowledge: The present study is among the largest series addressing the role of HHT for inoperable lung tumours. This technique is safe and effective and is not associated with a specific pattern of lung injury, at least at early and average time points.

Risk of radiation-induced pneumonitis after helical and static-port tomotherapy in lung cancer patients and experimental rats

BACKGROUND

Radiotherapy (RT) is one of the major non-operative treatment modalities for treating lung cancer. Tomotherapy is an advanced type of intensity-modulated radiotherapy (IMRT) in which radiation may be delivered in a helical fashion. However, unexpected pneumonitis may occur in patients treated with tomotherapy, especially in combination with chemotherapy, as a result of extensive low-dose radiation of large lung volumes. The aim of our study was to investigate the risk of radiation-induced pneumonitis after helical-mode and static-mode tomotherapy in patients with lung cancer and in an animal model.

METHOD

A total of 63 patients with primary lung cancer who were treated with static or helical tomotherapy with or without concurrent chemoradiotherapy (CCRT) were analyzed. Additionally, rats with radiation-induced pulmonary toxicity, which was induced by the application of helical or static tomography with or without CCRT, were evaluated.

RESULTS

Helical-mode tomotherapy resulted in a significantly higher rate of late radiation pneumonitis in lung cancer patients than static-mode tomotherapy when evaluated by the Radiation Therapy Oncology Group (RTOG) and National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) scoring system. In the animal model, helical tomotherapy alone induced significantly higher expression of interleukin (IL)-1α, IL-1β, IL-6, and transforming growth factor (TGF)-β in lung specimens, especially on the untreated side, compared to static tomotherapy alone. Additionally, rats treated with helical tomotherapy and CCRT demonstrated significantly higher expression of inflammatory cytokines compared to those treated with static tomotherapy and CCRT.

CONCLUSION

Rat models treated with tomotherapy with or without CCRT could present similar patterns of pulmonary toxicity to those shown in lung cancer patients. The models can be used in further investigations of radiation induced pulmonary toxicity.