Predicting Overall Survival After Stereotactic Ablative Radiation Therapy in Early-Stage Lung Cancer: Development and External Validation of the Amsterdam Prognostic Model

Development and validation of a prognostic nomogram in patients aged ≥65 years with stage I-II non-small cell lung cancer treated with stereotactic body radiotherapy

INTRODUCTION

This study aims to discern the efficacy and toxicity of stereotactic body radiotherapy (SBRT) in older adults with stage I-II non-small cell lung cancer (NSCLC) and establish a prognostic nomogram for these patients.

MATERIALS AND METHODS

One hundred forty-two patients (aged ≥65 years) with clinically-confirmed stage I-II NSCLC treated with SBRT from 2009 to 2020 were enrolled in the study. Primary end points included overall survival (OS), progression free survival (PFS), cumulative incidences of local failure (LF), regional failure (RF), distant failure (DF), and toxicity. A nomogram for OS was developed and validated internally using one thousand bootstrap resamplings.

RESULTS

The median times to LF, RF, and DF were 22.1 months, 26.9 months and 24.1 months, respectively. The 1-, 3-, and 5-year PFS rates from the start of SBRT were 79.4 %, 53.1 %, and 38.9 %, respectively. Performance status, pre-SBRT platelet to lymphocyte ratio (PLR), and planning tumor volume (PTV) were predictive of PFS. The 1-, 3-, and 5-year OS rates from the start of SBRT were 90.8 %, 67.9 % and 47.6 %, respectively. In multivariate analysis, good performance status, a low level of pre-SBRT PLR, and small tumor size were associated with better prognosis, all of which were included in the nomogram. The model showed optimal discrimination, with a C-index of 0.651 and good calibration. The most common adverse reactions were grade 1-2, such as anemia, cough, and fatigue.

DISCUSSION

SBRT is a reasonable treatment modality for early-stage NSCLC in older adults. It achieved good survival outcomes and low toxicity. The proposed nomogram may be able to estimate individual outcomes for these patients.

Exploring published and novel pre-treatment CT and PET radiomics to stratify risk of progression among early-stage non-small cell lung cancer patients treated with stereotactic radiation

PURPOSE

Disease progression after definitive stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) occurs in 20-40% of patients. Here, we explored published and novel pre-treatment CT and PET radiomics features to identify patients at risk of progression.

MATERIALS/METHODS

Published CT and PET features were identified and explored along with 15 other CT and PET features in 408 consecutively treated early-stage NSCLC patients having CT and PET < 3 months pre-SBRT (training/set-aside validation subsets: n = 286/122). Features were associated with progression-free survival (PFS) using bootstrapped Cox regression (Bonferroni-corrected univariate predictor: p ≤ 0.002) and only non-strongly correlated predictors were retained (|Rs|<0.70) in forward-stepwise multivariate analysis.

RESULTS

Tumor diameter and SUVmax were the two most frequently reported features associated with progression/survival (in 6/20 and 10/20 identified studies). These two features and 12 of the 15 additional features (CT: 6; PET: 6) were candidate PFS predictors. A re-fitted model including diameter and SUVmax presented with the best performance (c-index: 0.78; log-rank p-value < 0.0001). A model built with the two best additional features (CTspiculation1 and SUVentropy) had a c-index of 0.75 (log-rank p-value < 0.0001).

CONCLUSIONS

A re-fitted pre-treatment model using the two most frequently published features - tumor diameter and SUVmax - successfully stratified early-stage NSCLC patients by PFS after receiving SBRT.

Survival prediction for stage I-IIIA non-small cell lung cancer using deep learning

BACKGROUND AND PURPOSE

The aim of this study was to develop and evaluate a prediction model for 2-year overall survival (OS) in stage I-IIIA non-small cell lung cancer (NSCLC) patients who received definitive radiotherapy by considering clinical variables and image features from pre-treatment CT-scans.

MATERIALS AND METHODS

NSCLC patients who received stereotactic radiotherapy were prospectively collected at the UMCG and split into a training and a hold out test set including 189 and 81 patients, respectively. External validation was performed on 228 NSCLC patients who were treated with radiation or concurrent chemoradiation at the Maastro clinic (Lung1 dataset). A hybrid model that integrated both image and clinical features was implemented using deep learning. Image features were learned from cubic patches containing lung tumours extracted from pre-treatment CT scans. Relevant clinical variables were selected by univariable and multivariable analyses.

RESULTS

Multivariable analysis showed that age and clinical stage were significant prognostic clinical factors for 2-year OS. Using these two clinical variables in combination with image features from pre-treatment CT scans, the hybrid model achieved a median AUC of 0.76 [95 % CI: 0.65-0.86] and 0.64 [95 % CI: 0.58-0.70] on the complete UMCG and Maastro test sets, respectively. The Kaplan-Meier survival curves showed significant separation between low and high mortality risk groups on these two test sets (log-rank test: p-value < 0.001, p-value = 0.012, respectively) CONCLUSION: We demonstrated that a hybrid model could achieve reasonable performance by utilizing both clinical and image features for 2-year OS prediction. Such a model has the potential to identify patients with high mortality risk and guide clinical decision making.

Novel Harmonization Method for Multi-Centric Radiomic Studies in Non-Small Cell Lung Cancer

The purpose of this multi-centric work was to investigate the relationship between radiomic features extracted from pre-treatment computed tomography (CT), positron emission tomography (PET) imaging, and clinical outcomes for stereotactic body radiation therapy (SBRT) in early-stage non-small cell lung cancer (NSCLC). One-hundred and seventeen patients who received SBRT for early-stage NSCLC were retrospectively identified from seven Italian centers. The tumor was identified on pre-treatment free-breathing CT and PET images, from which we extracted 3004 quantitative radiomic features. The primary outcome was 24-month progression-free-survival (PFS) based on cancer recurrence (local/non-local) following SBRT. A harmonization technique was proposed for CT features considering lesion and contralateral healthy lung tissues using the LASSO algorithm as a feature selector. Models with harmonized CT features (B models) demonstrated better performances compared to the ones using only original CT features (C models). A linear support vector machine (SVM) with harmonized CT and PET features (A1 model) showed an area under the curve (AUC) of 0.77 (0.63–0.85) for predicting the primary outcome in an external validation cohort. The addition of clinical features did not enhance the model performance. This study provided the basis for validating our novel CT data harmonization strategy, involving delta radiomics. The harmonized radiomic models demonstrated the capability to properly predict patient prognosis.

Predicting 2-year survival in stage I-III non-small cell lung cancer: the development and validation of a scoring system from an Australian cohort

Background

There are limited data on survival prediction models in contemporary inoperable non-small cell lung cancer (NSCLC) patients. The objective of this study was to develop and validate a survival prediction model in a cohort of inoperable stage I-III NSCLC patients treated with radiotherapy.

Methods

Data from inoperable stage I-III NSCLC patients diagnosed from 1/1/2016 to 31/12/2017 were collected from three radiation oncology clinics. Patient, tumour and treatment-related variables were selected for model inclusion using univariate and multivariate analysis. Cox proportional hazards regression was used to develop a 2-year overall survival prediction model, the South West Sydney Model (SWSM) in one clinic (n = 117) and validated in the other clinics (n = 144). Model performance, assessed internally and on one independent dataset, was expressed as Harrell’s concordance index (c-index).

Results

The SWSM contained five variables: Eastern Cooperative Oncology Group performance status, diffusing capacity of the lung for carbon monoxide, histological diagnosis, tumour lobe and equivalent dose in 2 Gy fractions. The SWSM yielded a c-index of 0.70 on internal validation and 0.72 on external validation. Survival probability could be stratified into three groups using a risk score derived from the model.

Conclusions

A 2-year survival model with good discrimination was developed. The model included tumour lobe as a novel variable and has the potential to guide treatment decisions. Further validation is needed in a larger patient cohort.

Radiation Therapy Planning of Thoracic Tumors: A Review of Challenges Associated With Lung Toxicities and Potential Perspectives of Gallium-68 Lung PET/CT Imaging

Despite the introduction of new radiotherapy techniques, such as intensity modulated radiation therapy or stereotactic body radiation therapy, radiation induced lung injury remains a significant treatment related adverse event of thoracic radiation therapy. Functional lung avoidance radiation therapy is an emerging concept in the treatment of lung disease to better preserve lung function and to reduce pulmonary toxicity. While conventional ventilation/perfusion (V/Q) lung scintigraphy is limited by a relatively low spatial and temporal resolution, the recent advent of ⁶⁸Gallium V/Q lung PET/CT imaging offers a potential to increase the accuracy of lung functional mapping and to better tailor lung radiation therapy plans to the individual's lung function. Lung PET/CT imaging may also improve our understanding of radiation induced lung injury compared to the current anatomical based dose–volume constraints. In this review, recent advances in radiation therapy for the management of primary and secondary lung tumors and in V/Q PET/CT imaging for the assessment of functional lung volumes are reviewed. The new opportunities and challenges arising from the integration of V/Q PET/CT imaging in radiation therapy planning are also discussed.

Use of comorbidity indices in patients with any cancer, breast cancer, and human epidermal growth factor receptor-2-positive breast cancer: A systematic review

Objective

To identify comorbidity indices that have been validated in cancer populations, with a focus on breast cancer and human epidermal growth factor receptor-2-positive (HER2+) breast cancer.

Study design and setting

A systematic review of the literature on the use of comorbidity indices in any cancer, breast cancer, and HER2+ breast cancer using Ovid and PubMed.

Results

The final data set comprised 252 articles (252 any cancer, 39 breast cancer, 7 HER2+ breast cancer). The most common cancers assessed were hematologic and breast, and the most common comorbidity index used was the Charlson Comorbidity Index (CCI) or a CCI derivative. Most validity testing of comorbidity indices used predictive validity based on survival outcomes. Hazard ratios for survival outcomes generally found that a higher comorbidity burden (measured by CCI) increased mortality risk in patients with breast cancer. All breast-cancer studies that validated comorbidity indices used CCI-based indices. Only one article validated a comorbidity index in HER2+ breast cancer.

Conclusion

CCI-based indices are the most appropriate indices to use in the general breast-cancer population. There is insufficient validation of any comorbidity index in HER2+ breast cancer to provide a recommendation, indicating a future need to validate these instruments in this population.

Integration of Risk Survival Measures Estimated From Pre- and Posttreatment Computed Tomography Scans Improves Stratification of Patients With Early-Stage Non-small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy

PURPOSE

To predict overall survival of patients receiving stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (ES-NSCLC), we developed a radiomic model that integrates risk of death estimates and changes based on pre- and posttreatment computed tomography (CT) scans. We hypothesize this innovation will improve our ability to stratify patients into various oncologic outcomes with greater accuracy.

METHODS AND MATERIALS

Two cohorts of patients with ES-NSCLC uniformly treated with SBRT (a median dose of 50 Gy in 4-5 fractions) were studied. Prediction models were built on a discovery cohort of 100 patients with treatment planning CT scans, and then were applied to a separate validation cohort of 60 patients with pre- and posttreatment CT scans for evaluating their performance.

RESULTS

Prediction models achieved a c-index up to 0.734 in predicting survival outcomes of the validation cohort. The integration of the pretreatment risk of survival measures (risk-high vs risk-low) and changes (risk-increase vs risk-decrease) in risk of survival measures between the pretreatment and posttreatment scans further stratified the patients into 4 subgroups (risk: high, increase; risk: high, decrease; risk: low, increase; risk: low, decrease) with significant difference (χ² = 18.549, P = .0003, log-rank test). There was also a significant difference between the risk-increase and risk-decrease groups (χ² = 6.80, P = .0091, log-rank test). In addition, a significant difference (χ² = 7.493, P = .0062, log-rank test) was observed between the risk-high and risk-low groups obtained based on the pretreatment risk of survival measures.

CONCLUSION

The integration of risk of survival measures estimated from pre- and posttreatment CT scans can help differentiate patients with good expected survival from those who will do more poorly following SBRT. The analysis of these radiomics-based longitudinal risk measures may help identify patients with early-stage NSCLC who will benefit from adjuvant treatment after lung SBRT, such as immunotherapy.

The development and external validation of an overall survival nomogram in medically inoperable centrally located early-stage non-small cell lung carcinoma

BACKGROUND AND PURPOSE

Current nomograms predicting survival prognosis after stereotactic body radiation therapy (SBRT) in non-small cell lung cancer (NSCLC) are based on peripherally located tumors. However, patients with a central lung tumor tend to be older, the tumor is often larger and fraction-schedules are risk-adapted. Therefore, we developed and externally validated a nomogram to predict overall survival (OS) in patients having centrally located early-stage NSCLC treated with SBRT.

MATERIALS AND METHODS

Patients who underwent SBRT for centrally located NSCLC were identified and baseline characteristics were obtained. A nomogram was built to predict 6-month, 1-, 2- and 3-year OS using Cox proportional hazards model. The model building procedure was validated using bootstrap sampling. To determine generalizability, external validation was performed on a cohort of patients with central NSCLC treated with SBRT from another center. Discriminatory ability was measured with the concordance index (C-index) and calibration plots were used to compare Kaplan-Meier-estimated and nomogram-predicted OS.

RESULTS

The nomogram was built on data of 220 patients and consisted of the following variables: PTV, age, WHO performance status, tumor lobe location and ultracentral location. The C-index of the nomogram (corrected for optimism) was moderate at 0.64 (95% confidence interval (CI) 0.59-0.69). Calibration plots showed favorable predictive accuracy. The external validation showed acceptable validity with a C-index of 0.62 (95% CI 0.61-0.64).

DISCUSSION

We developed and externally validated the first nomogram to estimate the OS-probability in patients with centrally located NSCLC treated with SBRT. This nomogram is based on 5 patient and tumor characteristics and gives an individualized survival prediction.

Validating impact of pretreatment tumor growth rate on outcome of early-stage lung cancer treated with stereotactic body radiation therapy

BACKGROUND

To assess correlation of pretreatment specific growth rate (SGR) value of 0.43 × 10^-2 with overall and failure-free survival of patients with early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT).

METHODS

A retrospective chart review of 160 patients with pathologically confirmed stage I NSCLC treated with SBRT between June 2010 and December 2012 in a large, tertiary cancer institute was undertaken. Both diagnostic and archived planning CT were uploaded to the treatment planning system to determine tumor volume at diagnosis (GTV1) and planning time (GTV2). The time (t) between both CTs was recorded. SGR was calculated using GTV1, GTV2, and t. The median SGR (0.43 × 10^-2 ) from our previous data was used to group patients into low and high SGR cohorts. Log-rank test was used to compare overall (OS) and failure-free survivals (FFS) of SGR groups.

RESULTS

The median time interval between diagnostic and planning CT scans was 87 days. The median OS was 38 and 66 months for high and low SGR cohorts, respectively (P = 0.03). The median FFS was 27 and 55 months for high and low SGR cohorts, respectively (P = 0.005). High SGR (P < 0.05), male gender (P = <0.01), and GTV2 (P = <0.05) were associated with poorer FFS.

CONCLUSIONS

High SGR was associated with poorer outcome in patients with early-stage NSCLC treated with SBRT. SGR can be used in conjunction with other well-known predictive factors to formulate a practical predictive model to identify subgroups of the patient at higher risk of recurrence after SBRT.

Oncologic Outcomes of Surgery Versus SBRT for Non-Small-Cell Lung Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

The optimal treatment of stage I non-small-cell lung carcinoma is subject to debate. The aim of this study was to compare overall survival and oncologic outcomes of lobar resection (LR), sublobar resection (SR), and stereotactic body radiotherapy (SBRT).

METHODS

A systematic review and meta-analysis of oncologic outcomes of propensity matched comparative and noncomparative cohort studies was performed. Outcomes of interest were overall survival and disease-free survival. The inverse variance method and the random-effects method for meta-analysis were utilized to assess the pooled estimates.

RESULTS

A total of 100 studies with patients treated for clinical stage I non-small-cell lung carcinoma were included. Long-term overall and disease-free survival after LR was superior over SBRT in all comparisons, and for most comparisons, SR was superior to SBRT. Noncomparative studies showed superior long-term overall and disease-free survival for both LR and SR over SBRT. Although the papers were heterogeneous and of low quality, results remained essentially the same throughout a large number of stratifications and sensitivity analyses.

CONCLUSION

Results of this systematic review and meta-analysis showed that LR has superior outcomes compared to SBRT for cI non-small-cell lung carcinoma. New trials are underway evaluating long-term results of SBRT in potentially operable patients.

Development and external validation of a nomogram to predict overall survival following stereotactic body radiotherapy for early-stage lung cancer

BACKGROUND

Prognostication tools for early-stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT) are currently lacking. The purpose of this study was to develop and externally validate a nomogram to predict overall survival in individual patients with peripheral early-stage disease.

METHODS

A total of 587 NSCLC patients treated with biologically effective dose > 100 Gy₁₀ were eligible. A Cox proportional hazards model was used to build a nomogram to predict 6-month, 1-year, 3-year and 5-year overall survival. Internal validation was performed using bootstrap sampling. External validation was performed in a separate cohort of 124 NSCLC patients with central tumors treated with SBRT. Discriminatory ability was measured by the concordance index (C-index) while predictive accuracy was assessed with calibration slope and plots.

RESULTS

The resulting nomogram was based on six prognostic factors: age, sex, Karnofsky Performance Status, operability, Charlson Comorbidity Index, and tumor diameter. The slope of the calibration curve for nomogram-predicted versus Kaplan-Meier-estimated overall survival was 0.77. The C-index of the nomogram (corrected for optimism) was moderate at 0.64. In the external validation cohort, the model yielded a C-index of 0.62.

CONCLUSIONS

We established and validated a nomogram which can provide individual survival predictions for patients with early stage lung cancer treated with SBRT. The nomogram may assist patients and clinicians with treatment decision-making.

Definitive Management of Presumed Synchronous Early Stage Non-Small Cell Lung Cancers: Outcomes and Utility of Stereotactic Ablative Radiation Therapy

PURPOSE

Management of synchronous early-stage non-small cell lung cancer (NSCLC) remains controversial because resection is not always feasible. This study evaluates efficacy and patterns of failure after SABR for synchronous early-stage NSCLC.

METHODS AND MATERIALS

From 2005 to 2015, patients presenting with ≥2 synchronous NSCLC tumors (T1a-T2b) and receiving SABR to ≥1 lesion were reviewed. The most common prescriptions were 50 Gy in 4 or 70 Gy in 10 fractions. Patients underwent multidisciplinary management with workup including chest computed tomography and positron emission tomography/computed tomography, plus brain imaging and endoscopic bronchial ultrasound for most patients to rule out mediastinal and distant disease. Synchronous lesions were defined as multiple ipsilateral or contralateral intrapulmonary lesions diagnosed within 6 months.

RESULTS

Of 912 patients treated with SABR for early-stage NSCLC at our institution, 82 (9%) presented with synchronous disease, with a total of 169 lesions. SABR was delivered to 142 lesions (84%), with 57 patients (69.5%) receiving SABR for all sites. Median overall survival (OS) and progression-free survival (PFS) were 5.1 and 2.7 years, respectively. At a median follow-up of 58 months, OS was 67% and 52% at 3 and 5 years, and corresponding PFS was 47% and 29%. Thirty-nine patients (48%) had progression, with 21 (26%) experiencing distant failure, and intralobar recurrence was among the first failure for 15 patients (18%). Of the 142 SABR-treated sites, these included 6 in-field (4%) and 4 marginal (3%) recurrences. There were no grade ≥3 adverse events. Among patients receiving SABR for all sites, there were no differences in OS (P = .946), PFS (P = .980), local control (P = .683), regional and distant control (P = .656), or toxicity (P = .791). On multivariable analysis, ipsilateral synchronous disease was associated with greater regional and distant failure (hazard ratio, 2.691; P = .025).

CONCLUSIONS

Synchronous NSCLC can be managed with definitive local therapy. With high control rates and favorable outcomes, SABR is an effective and feasible treatment for synchronous early-stage NSCLC.

Predicting 5-Year Progression and Survival Outcomes for Early Stage Non-small Cell Lung Cancer Treated with Stereotactic Ablative Radiation Therapy: Development and Validation of Robust Prognostic Nomograms

PURPOSE

Our purpose was to develop predictive nomograms for overall survival (OS), progression-free survival (PFS), and time-to-progression (TTP) at 5 years in patients with early-stage non-small cell lung cancer (ES-NSCLC) treated with stereotactic ablative radiation therapy (SABR).

METHODS AND MATERIALS

The study cohort included 714 ES-NSCLC patients treated with SABR from 2004-2015 with median follow-up of 59 months, divided into training and testing sets (8:2), with the former used for nomogram development. The least absolute shrinkage and selection operator were initially employed to screen for predictors of OS, PFS, and TTP, and identified predictors were subsequently applied toward Cox proportional hazards regression modeling. Significant predictors (P < .05) on multivariable regression were then used to develop nomograms, which were validated via evaluation of concordance indexes (C-index) and calibration plots. Finally, Kaplan-Meier method and Gray's test were employed to compare and confirm differences in outcomes among various groups and explore prognostic factors associated with local versus distant disease progression.

RESULTS

Significant predictors of both OS and PFS at 5 years included age, sex, Charlson comorbidity index, diffusing capacity of carbon monoxide, systemic immune-inflammation index, and tumor size (P ≤ .01 for all). Eastern Cooperative Oncology Group performance status predicted for OS as well (P = .01), and both tumor size (P < .01) and minimum biological equivalent dose to 95% of planning target volume (PTV D95 BED₁₀; P < .01) were predictive of TTP. The C-indexes for the OS, PFS, and TTP nomograms were 0.73, 0.68, and 0.60 in the training data set and 0.72, 0.66, and 0.59 in the testing data set, respectively. Tumor size > 2.45 cm and PTV D95 BED₁₀ < 113 Gy were significantly associated with both local and distant progression.

CONCLUSIONS

These prognostic nomograms can accurately predict for OS, PFS, and TTP at 5 years after SABR for ES-NSCLC and may thus help identify high-risk patients who could benefit from additional systemic therapy.

Prediction of early mortality following stereotactic body radiotherapy for peripheral early-stage lung cancer

BACKGROUND/PURPOSE

To investigate prognostic factors for death within 6 months of stereotactic body radiotherapy (SBRT) for patients with peripheral early-stage non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This analysis included 586 NSCLC patients with peripheral tumors treated with SBRT. Potential patient and tumor prognostic factors, including the Charlson Comorbidity Index (CCI) and Cumulative Illness Rating Scale (CIRS), were analyzed by logistic regression analysis for association with early mortality (death <6 months after SBRT). Additionally, CCI and CIRS were compared with respect to their predictive ability for early mortality by comparing multivariate models with each comorbidity index, and assessing their respective discriminatory abilities (C-index).

RESULTS

A total of 36 patients (6.1%) died within 6 months of the start of SBRT. With a median follow-up of 25 months, 3-year overall survival was 54%. CIRS and tumor diameter were significant predictors of early mortality on multivariate analysis (p = .001). Patients with a CIRS score of 8 or higher and a tumor diameter over 3 cm had a 6-month survival of 70% versus 97% for those lacking these two features (p < .001). CCI was not predictive for early mortality on univariate nor multivariate analysis; the model containing CCI had a C-index of 0.65 versus 0.70 for the model containing CIRS.

CONCLUSION

CIRS and tumor diameter predict for early-mortality in peripheral early-stage NSCLC treated with SBRT. CIRS may be a more useful comorbidity index than CCI in this population when assessing short-term life expectancy.

Defining Optimal Comorbidity Measures for Patients With Early-Stage Non-small cell lung cancer Treated With Stereotactic Body Radiation Therapy

PURPOSE

Comparison of overall survival (OS) between stereotactic body radiation therapy (SBRT) and other treatments for early-stage non-small cell lung cancer is confounded by differences in age, performance status, and medical comorbidity. We sought to define the most robust measurement for this population among 5 indices: age, Eastern Cooperative Oncology Group performance status, Adult Comorbidity Evaluation 27, Charlson Comorbidity Index (CCI), and age-adjusted CCI (CCIa).

METHODS AND MATERIALS

A total of 548 patients with stage I non-small cell lung cancer treated with SBRT were analyzed. Patients were divided into high- and low-risk groups for OS for each index using the log-rank test. Continuous and dichotomized models were compared via Akaike information criterion and the Vuong test. Multivariate Cox regression modeling was used with demographic information to determine the independent prognostic value of the continuous and dichotomized versions of the indices. The best was used to stratify the patients into as many significantly different cohorts as possible.

RESULTS

Optimal cut-points between high-risk and low-risk OS groups for age, Eastern Cooperative Oncology Group status, Adult Comorbidity Evaluation 27, CCI, and CCIa were ≥75 years, ≥1, ≥3, ≥3, and ≥6 with hazard ratios for death of 1.23 (95% confidence interval, 1.00-1.50), 1.66 (1.28-2.15), 1.37 (1.12-1.67), 1.43 (1.17-1.76), and 1.47 (1.20-1.80), respectively. Dichotomizing did not result in a significant loss of prognostic power. Although there was no significant difference in prognostic power among the indices, CCIa best predicted OS. CCIa divided the patients into 3 cohorts with median OS of 42 months, 33 months, and 23 months for scores of ≤5, 6 to 7, and ≥8, respectively.

CONCLUSIONS

CCIa was the best indicator of OS in every model employed with no loss of prognostic power with dichotomization. Dichotomization of CCIa (≥6) could be implemented in future comparisons of SBRT with OS. No cohort could be identified with a median survival of less than a year, for which treatment could be deemed futile.

Nomograms for predicting disease progression in patients of Stage I non-small cell lung cancer treated with stereotactic body radiotherapy

Objective

Non-local progression is a major concern in non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT). Herein we aimed to create a pre-treatment prognostic nomogram for patients with Stage I NSCLC receiving SBRT.

Methods

We retrospectively studied 182 eligible patients. Patients were randomly divided into a model (70%) group and a validation (30%) group. In the model group, thirteen parameters consisting of patient, treatment, and tumor factors were studied and multivariate Cox proportional hazards regression was performed to identify independent predictors for survival outcome, based on which we developed clinical nomogram. The nomogram was externally validated in the validation group.

Results

Multivariate analysis showed that tumor size (P = 0.011) was the only factor correlated with 2-year overall survival, whereas 2-year locoregional control (LRC) was significantly related to tumor size (P = 0.024) and the maximum standardized uptake value (SUVmax) (P = 0.044), so does 2-year progression-free survival (PFS) (tumor size: P = 0.026; SUVmax: P = 0.038). Nomogram for 2-year LRC and 2-year PFS were created based on aforementioned results. The C-indexes for the nomograms to predict 2-year LRC and PFS were 0.816 and 0.804, respectively, in model group, and were 0.729 and 0.731, respectively, in the validation group. Calibration plots also showed that the model performed well.

Conclusions

Tumor of larger size and higher SUVmax predisposed patients to early onset of locoregional and distant progression. The nomogram developed in our study would be helpful in clinical decision-making and selection of patients who may benefit from more rigorous follow-up and aggressive systemic treatment plan.

Predictors of Early Mortality in Cancer-Associated Thrombosis: Analysis of the RIETE Database

Cancer-associated thrombosis (CT) carries a high, heterogeneous, and poorly predicted likelihood of mortality. Thus, we aimed to define predictors of 30-day mortality in 10,025 patients with CT. In a randomly selected derivation cohort, we used recursive partitioning analysis to detect variables that select for a risk of mortality within 30 days. In a validation cohort, we evaluated our results using Cochran–Armitage test. The most common types of cancer were lung (16%), breast (14%), and colorectal (14%); median age was 69 years (range, 14–101); most had metastatic disease (63%); 13% of patients died within 30 days. In the derivation cohort ( n  = 6,660), a white blood cell (WBC) count in the highest quartile predicted early mortality (odds ratio, 7.8; 95% confidence interval [CI], 4.6–13.1); and the presence of metastatic disease, pulmonary embolism (PE), and immobility defined the risk of those with normal WBC count. We defined death risk according four sequential questions: (1) Does the patient have an elevated WBC count? (Yes, group D). (2) If no, does the patient have metastasis? (No, group A). (3) If yes, is the patient immobile? (Yes, group D). (4) If no, does the patient have a PE? (Yes, group C; no, group B). In the validation cohort ( n  = 3,365), the 30-day risk of death was 2.9% in group A (95% CI, 1.9–4.3), compared with 25% in group D (95% CI, 22.5–27.5), and there was a rate escalation between groups ( p for trend < 0.01). In conclusion, with four sequential questions, the risk of death in CT can be easily stratified. An elevated WBC count at baseline predicted 30-day mortality better than metastases, PE, or immobility.

Tumor Control and Toxicity for Common Stereotactic Body Radiation Therapy Dose-Fractionation Regimens in Stage I Non-Small Cell Lung Cancer

PURPOSE

To examine the impact of stereotactic body radiation therapy (SBRT) dose on outcomes in early-stage non-small cell lung cancer in a large single-institution series.

METHODS AND MATERIALS

We reviewed 600 patients treated from 2003 to 2012 for early-stage non-small cell lung cancer. The SBRT dose was at physician discretion on the basis of tumor size and location. Peripheral tumors were treated to 60 Gy in 3 fractions (homogeneous planning), 48-50 Gy in 4-5 fractions, or 30-34 Gy in 1 fraction. Central tumors were treated to 50 Gy in 5 fractions, 60 Gy in 8 fractions, or 50 Gy in 10 fractions. Patient, tumor, and treatment factors were assessed for their impact on patterns of failure, toxicity, and survival.

RESULTS

An SBRT dose of 54-60 Gy in 3 fractions was associated with a statistically significant lower rate of local failure (LF) (4.3% at 2 years) compared with 30-34 Gy in 1 fraction (21%), 48-50 Gy in 4-5 fractions (15.5%), and 50-60 Gy in 8-10 fractions (13.3%). Lower pre-SBRT hemoglobin and higher positron emission tomography standardized uptake value were also associated with LF. Nodal failure, distant failure, and overall survival were similar between fractionation groups. Pulmonary toxicity (crude rate, any grade) was slightly higher for 3 fractions (5.0%) compared with 1 (3.2%) or 4-5 fractions (3.8%). Chest wall toxicity was also higher for 3 (23.7%) compared with 1 (8.6%) or 4-5 (7.7%) fraction regimens.

CONCLUSIONS

Although higher biologically equivalent dose SBRT (150-180 Gy₁₀) may be associated with slightly lower LF, it was also associated with mildly increased toxicity and no difference in other patterns of failure or overall survival.

Comparison of particle beam therapy and stereotactic body radiotherapy for early stage non-small cell lung cancer: A systematic review and hypothesis-generating meta-analysis

PURPOSE

To assess hypo-fractionated particle beam therapy (PBT)'s efficacy relative to that of photon stereotactic body radiotherapy (SBRT) for early stage (ES) non-small cell lung cancer (NSCLC).

METHODS

Eligible studies were identified through extensive searches of the PubMed, Medline, Google-scholar, and Cochrane library databases from 2000 to 2016. Original English publications of ES NSCLC were included. A meta-analysis was performed to compare the survival outcome, toxicity profile, and patterns of failure following each treatment.

RESULTS

72 SBRT studies and 9 hypo-fractionated PBT studies (mostly single-arm) were included. PBT was associated with improved overall survival (OS; p=0.005) and progression-free survival (PFS; p=0.01) in the univariate meta-analysis. The OS benefit did not reach its statistical significance after inclusion of operability into the final multivariate meta-analysis (p=0.11); while the 3-year local control (LC) still favored PBT (p=0.03).

CONCLUSION

Although hypo-fractionated PBT may lead to additional clinical benefit when compared with photon SBRT, no statistically significant survival benefit from PBT over SBRT was observed in the treatment of ES NSCLC in this hypothesis-generating meta-analysis after adjusting for potential confounding variables.

Stereotactic Body Radiation Therapy in Octo- and Nonagenarians for the Treatment of Early-Stage Lung Cancer

PURPOSE

To determine the safety and efficacy of lung stereotactic body radiation therapy (SBRT) in octo- and nonagenarians and to compare their outcomes with those of younger patients.

METHODS AND MATERIALS

Patients with primary lung cancer treated with SBRT were identified from a multi-institutional (5 institutions) database of 1083 cases. Details of patient factors, treatment specifics, toxicity, and clinical outcomes were extracted from the database. All events were calculated from the end of radiation therapy. Estimates of local recurrence, regional recurrence, and distant metastases were calculated using the competing risk method. Cause-specific survival (CSS) and overall survival (OS) were calculated using the Kaplan-Meier method. Outcomes were compared for those aged <70, 70 to 79, and ≥80 years. Univariable and multivariable analyses were performed to determine associations with CSS and OS in patients aged ≥80 years.

RESULTS

The median (range) follow-up was 1.7 (1-10) years, and median age was 75 (41-94) years. There were 305 patients aged <70 years (28%), 448 aged 70 to 79 years (41%), and 330 aged ≥80 years (30%). There was no difference in 2-year local recurrence (4.2% vs 5.4% vs 3.7%, respectively, P=.7), regional recurrence (10.4% vs 7.8% vs 5.3%, P=.1), distant metastases (12.2% vs 7.7% vs 9.5%, P=.2), or CSS (90.6% vs 90.3% vs 90.4%, P=.6). Those aged ≥80 years had significantly lower 2-year OS (73.6% vs 67.2% vs 63.3%, P<.01). The grade 3+ pneumonitis rate was 1.3% versus 1.6% versus 1.5% (P=1.0) in patients aged <70, 70 to 79, and ≥80 years, respectively. The 90-day mortality rates for patients aged <70, 70 to 79, and ≥80 years were 1.3%, 2.5%, and 2.4% (P=.01), respectively. In patients aged ≥80 years OS was associated with T category (hazard ratio 1.7; P<.01).

CONCLUSION

Stereotactic body radiation therapy is a safe treatment modality in elderly patients (aged ≥80 years). Despite larger tumor volumes, the tumor control outcomes were comparable to those in younger patients treated with SBRT. All patients with early-stage lung cancer, regardless of age, should be considered for treatment with SBRT.

What do radiation oncologists require for future advancements in lung SBRT?

Stereotactic Body Radiotherapy (SBRT) is a well established therapeutic option for patients affected with peripheral early stage non-small cell lung cancer (NSCLC), given the positive clinical evidence accumulated so far on its efficacy and safety. SBRT is regarded as the best choice for inoperable patients, and could also be offered as an alternative to surgery to selected operable patients. More recently, its use for lung metastases progressively increased, and SBRT is now regarded as a low toxic and highly effective local therapy for lung oligometastases from different primary tumors, especially colorectal cancer. Improved planning and delivery techniques have facilitated over the years its use on large and/or centrally located primary tumors, and multiple nodules. Given the successful applications and the current wide dissemination of this technique, clinicians are now faced with an increasingly complex and multi-variable decision process. Some clinically relevant factors are still uncertain, and strategies are needed to reduce the risk of both local and distant failures. Secondly, aspects related to target delineation, dose prescription, image guidance and treatment planning still need to be fully addressed; this may hamper, at least for now, the standardization of SBRT procedures through different Institutions making any kind of direct outcomes comparison difficult. We here aim to provide a perspective on the current role of lung SBRT and its critical aspects, highlighting the potential future developments.