The Association of Incidental Radiation Dose to the Heart Base with Overall Survival and Cardiac Events after Curative-intent Radiotherapy for Non-small Cell Lung Cancer: Results from the NI-HEART Study

AIMS

Cardiac disease is a dose-limiting toxicity in non-small cell lung cancer radiotherapy. The dose to the heart base has been associated with poor survival in multiple institutional and clinical trial datasets using unsupervised, voxel-based analysis. Validation has not been undertaken in a cohort with individual patient delineations of the cardiac base or for the endpoint of cardiac events. The purpose of this study was to assess the association of heart base radiation dose with overall survival and the risk of cardiac events with individual heart base contours.

MATERIALS AND METHODS

Patients treated between 2015 and 2020 were reviewed for baseline patient, tumour and cardiac details and both cancer and cardiac outcomes as part of the NI-HEART study. Three cardiologists verified cardiac events including atrial fibrillation, heart failure and acute coronary syndrome. Cardiac substructure delineations were completed using a validated deep learning-based autosegmentation tool and a composite cardiac base structure was generated. Cox and Fine-Gray regressions were undertaken for the risk of death and cardiac events.

RESULTS

Of 478 eligible patients, most received 55 Gy/20 fractions (96%) without chemotherapy (58%), planned with intensity-modulated radiotherapy (71%). Pre-existing cardiovascular morbidity was common (78% two or more risk factors, 46% one or more established disease). The median follow-up was 21.1 months. Dichotomised at the median, a higher heart base Dmax was associated with poorer survival on Kaplan-Meier analysis (20.2 months versus 28.3 months; hazard ratio 1.40, 95% confidence interval 1.14-1.75, P = 0.0017) and statistical significance was retained in multivariate analyses. Furthermore, heart base Dmax was associated with pooled cardiac events in a multivariate analysis (hazard ratio 1.75, 95% confidence interval 1.03-2.97, P = 0.04).

CONCLUSIONS

Heart base Dmax was associated with the rate of death and cardiac events after adjusting for patient, tumour and cardiovascular factors in the NI-HEART study. This validates the findings from previous unsupervised analytical approaches. The heart base could be considered as a potential sub-organ at risk towards reducing radiation cardiotoxicity.

Simulation CT Features and Radiation Cardiotoxicity in Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Radiation cardiotoxicity is a significant clinical dilemma in non-small cell lung cancer (NSCLC) radiation therapy (RT). Baseline cardiovascular (CV) status may influence the risk of cardiotoxicity, and may be ascertainable from the appearance of the heart on simulation computed tomography (CT). We examined the association of CT features with incidental heart dose and risk of cardiac events in NSCLC.

MATERIALS/METHODS

Patients treated with curative-intent RT between 2015 and 2020 at a regional center were identified. Clinical notes were interrogated for baseline patient and CV health details, and follow-up CV events. Cardiac events were verified by a cardiologist. A deep learning-based auto-segmentation tool was applied, allowing extraction of a pre-specified list of volume parameters in a programming environment. CAC was graded as none, mild, moderate and severe in patients with a non-contrast scan. The craniocaudal relationship of the PTV and heart (Feng atlas) were annotated.

RESULTS

A total of 478 patients were included, with a median age of 70 and Charlson Index of 5. The median mean heart dose was 6.3 Gy (IQR 2.7-11.4). The median lung V20 was 20.0% (IQR 14.8-27.1). Cardiovascular risk factors were common, with most patients having 2 (39%) or 3 (31%). A history of previous cardiac events was common, including myocardial infarction (14%), arrhythmia (11%) or heart failure (9%). A total of 6.9% and 7.1% patients developed a new atrial arrhythmia (AA) or heart failure (HF) after completing RT. The volume metrics with the highest AUC for AA and HF events were the left atrium (LA) (AUC 0.67, p = 0.0002) and left ventricle:right ventricle (LV:RV) ratio (AUC 0.66, p = 0.0021). Kaplan-Meier analysis for cardiac events dichotomizing at the optimal cut-point for maximum sensitivity and specificity demonstrated significantly different rates for both AA (LA 109cc, HR 3.35, 95% CI 1.64-6.83, p = 0.0009) and HF (LV:RV ratio 1.61, HR 2.37, 95% CI 1.19-4.74, p = 0.0143). Only 2 patients with non-contrast scans developed a myocardial infarction, both had mild CAC. The incidence of pooled cardiac events was not significantly different between patients with no (n = 2/21, 9.5%), mild (n = 10/38, 26.3%), moderate (n = 8/53, 15.1%) and severe (n = 7/24, 29.2%) CAC (p = 0.3916). Where the inferior border of the PTV was above the superior border of the heart, mean heart dose was significantly lower than compared with overlap of levels (1.9 Gy v 9.7 Gy, p<0.0001), and this was true for 3DCRT (n = 139, p<0.001), IMRT (n = 94, p<0.001) and VMAT (n = 145, p<0.001) patients.

CONCLUSION

LA volume and LV:RV volume ratio are predictive for the development of AA and HF respectively. CAC grade did not differentiate patients by risk of cardiac events. Where the craniocaudal level of the PTV doesn't overlap with the level of the heart, the cardiac dose is likely to be very low. Several simulation CT features are associated with cardiac events following treatment for NSCLC and prospective evidence of cardiac risk could enable medical optimization prior to RT.

Patient-Level and Endpoint-Specific Clinico-Dosimetric Analysis of the Cardiac Base as a Mediator of Radiation Cardiotoxicity in Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Cardiac disease is a dose-limiting toxicity in non-small cell lung cancer (NSCLC) radiation therapy. Radiation dose to the cardiac base is associated with poor overall survival in several clinical studies, but has not been validated in a non-dose escalated cohort, or with individual patient delineations. In this study we examined the impact of cardiac base dose on overall survival (OS) and cardiac events (CEs), and interrogated the relationships of the substructures comprising the heart base with OS and CEs.

MATERIALS/METHODS

Patients with stage I-III NSCLC treated with curative-intent radiation therapy between 2015 and 2020 at a regional cancer center were identified. Clinical notes were examined for baseline patient, tumor and cardiac details, and both cancer and cardiac outcomes. Three cardiologists verified CEs. Cardiac delineations were completed using a validated deep learning-based autosegmentation tool. Cox and Fine and Gray regressions were undertaken for the risk of death and CEs respectively, accounting for pre-specified evidence-based dose metrics and clinically relevant cardiac covariates.

RESULTS

Most patients received 55 Gy/20# (n = 461/478, 96%) without chemotherapy (58%), planned with VMAT (51%) or IMRT (20%). Pre-existing cardiovascular morbidity was common, with 78% having ≥2 risk factors, and 46% having >1 established cardiac disease. The median follow-up was 21.1 months. Dichotomized at the median, higher heart base Dmax was associated with poorer survival on Kaplan-Meier analysis (21.6 months (95% CI 19.3-24.9) versus 29.4 months (95% CI 21.6-36.6), p = 0.021), and remained significant when statistically compared in published multivariate models. In a multivariate analysis for pooled acute CEs, heart base Dmax was associated with CEs (HR 1.75, 95% CI 1.01-1.06, p = 0.04), but this was not the case for individual CEs. Using Fine and Gray models to account for the competing risk of death, left main coronary maximum dose was associated with atrial fibrillation (p = 0.024), proximal right coronary artery V15 (p = 0.023) and mean dose (p = 0.032), and the right atrium mean dose (p = 0.029) were associated with heart failure. No dose-volume metrics were significantly associated with acute coronary syndrome. None of the constituent base substructures dose were significantly associated with death.

CONCLUSION

Dose to the heart base was associated with increased mortality and an increased pooled cardiac event rate. Accounting for endpoint-specific clinical covariates, only select constituent substructures of the heart base were associated with CEs and no substructures were independently associated with survival. Together, these findings are suggestive of possible interplay between the constituent base substructures in their mediation of radiation cardiotoxicity.

Neutrophil-Lymphocyte Ratio and Absolute Lymphocyte Count as Prognostic Markers in Patients Treated with Curative-intent Radiotherapy for Non-small Cell Lung Cancer

AIMS

The neutrophil-lymphocyte ratio (NLR) and the absolute lymphocyte count (ALC) have been proposed as prognostic markers in non-small cell lung cancer (NSCLC). The objective of this study was to examine the association of NLR/ALC before and after curative-intent radiotherapy for NSCLC on disease recurrence and overall survival.

MATERIALS AND METHODS

A retrospective study of consecutive patients who underwent curative-intent radiotherapy for NSCLC across nine sites in the UK from 1 October 2014 to 1 October 2016. A multivariate analysis was carried out to assess the ability of pre-treatment NLR/ALC, post-treatment NLR/ALC and change in NLR/ALC, adjusted for confounding factors using the Cox proportional hazards model, to predict disease recurrence and overall survival within 2 years of treatment.

RESULTS

In total, 425 patients were identified with complete blood parameter values. None of the NLR/ALC parameters were independent predictors of disease recurrence. Higher pre-NLR, post-NLR and change in NLR plus lower post-ALC were all independent predictors of worse survival. Receiver operator curve analysis found a pre-NLR > 2.5 (odds ratio 1.71, 95% confidence interval 1.06-2.79, P < 0.05), a post-NLR > 5.5 (odds ratio 2.36, 95% confidence interval 1.49-3.76, P < 0.001), a change in NLR >3.6 (odds ratio 2.41, 95% confidence interval 1.5-3.91, P < 0.001) and a post-ALC < 0.8 (odds ratio 2.86, 95% confidence interval 1.76-4.69, P < 0.001) optimally predicted poor overall survival on both univariate and multivariate analysis when adjusted for confounding factors. Median overall survival for the high-versus low-risk groups were: pre-NLR 770 versus 1009 days (P = 0.34), post-NLR 596 versus 1287 days (P ≤ 0.001), change in NLR 553 versus 1214 days (P ≤ 0.001) and post-ALC 594 versus 1287 days (P ≤ 0.001).

CONCLUSION

NLR and ALC, surrogate markers for systemic inflammation, have prognostic value in NSCLC patients treated with curative-intent radiotherapy. These simple and readily available parameters may have a future role in risk stratification post-treatment to inform the intensity of surveillance protocols.

Reducing the Risk of Death From Pneumocystis jirovecii Pneumonia After Radical Radiation Therapy to the Lung

AIMS

Lung cancer is the leading cause of cancer death. Radiotherapy given in the curative setting is associated with a 3% risk of death from Pneumocystis jirovecii pneumonia (PJP). Prolonged courses of high-dose steroids also increase the risk of PJP. International guidelines recommend the use of chemoprophylaxis with trimethoprim-sulfamethoxazole for patients at high risk. We assessed the effect of an intervention designed to reduce the impact of PJP.

MATERIALS AND METHODS

Prophylaxis guidelines were introduced in 2016. Case records of patients treated with radical radiotherapy were examined for the periods 2014 to 2015 (pre-intervention) and 2017 to 2018 (post-intervention). In total, 247 patients were treated pre-intervention and 334 post-intervention.

RESULTS

Freedom from PJP death at 1 year was 96% before intervention and 99% after (hazard ratio 0.3, 95% confidence interval 0.1-0.9, P = 0.029). Although the rate of use of chemoprophylaxis according to the guideline rose from 1% to 13% (P = 0.003), the use of high-dose steroids also fell from 35% to 16% (P < 0.00001).

CONCLUSIONS

Reducing radiotherapy-associated infections is an important component of radical treatment in lung cancer. Highlighting chemoprophylaxis guidelines reduced the death rate from PJP, with an associated more judicious use of steroids. Advocating prophylaxis in patients with lymphocyte count <0.6 × 109/l is the next intervention to be studied.

Predicting the Risk of Disease Recurrence and Death Following Curative-intent Radiotherapy for Non-small Cell Lung Cancer: The Development and Validation of Two Scoring Systems From a Large Multicentre UK Cohort

AIMS

There is a paucity of evidence on which to produce recommendations on neither the clinical nor the imaging follow-up of lung cancer patients after curative-intent radiotherapy. In the 2019 National Institute for Health and Care Excellence lung cancer guidelines, further research into risk-stratification models to inform follow-up protocols was recommended.

MATERIALS AND METHODS

A retrospective study of consecutive patients undergoing curative-intent radiotherapy for non-small cell lung cancer from 1 October 2014 to 1 October 2016 across nine UK trusts was carried out. Twenty-two demographic, clinical and treatment-related variables were collected and multivariable logistic regression was used to develop and validate two risk-stratification models to determine the risk of disease recurrence and death.

RESULTS

In total, 898 patients were included in the study. The mean age was 72 years, 63% (562/898) had a good performance status (0-1) and 43% (388/898), 15% (134/898) and 42% (376/898) were clinical stage I, II and III, respectively. Thirty-six per cent (322/898) suffered disease recurrence and 41% (369/898) died in the first 2 years after radiotherapy. The ASSENT score (age, performance status, smoking status, staging endobronchial ultrasound, N-stage, T-stage) was developed, which stratifies the risk for disease recurrence within 2 years, with an area under the receiver operating characteristic curve (AUROC) for the total score of 0.712 (0.671-0.753) and 0.72 (0.65-0.789) in the derivation and validation sets, respectively. The STEPS score (sex, performance status, staging endobronchial ultrasound, T-stage, N-stage) was developed, which stratifies the risk of death within 2 years, with an AUROC for the total score of 0.625 (0.581-0.669) and 0.607 (0.53-0.684) in the derivation and validation sets, respectively.

CONCLUSIONS

These validated risk-stratification models could be used to inform follow-up protocols after curative-intent radiotherapy for lung cancer. The modest performance highlights the need for more advanced risk prediction tools.

Association between minimum inhibitory concentration, beta-lactamase genes and mortality for patients treated with piperacillin/tazobactam or meropenem from the MERINO study

INTRODUCTION

This study aims to assess the association of piperacillin/tazobactam and meropenem minimum inhibitory concentration (MIC) and beta-lactam resistance genes with mortality in the MERINO trial.

METHODS

Blood culture isolates from enrolled patients were tested by broth microdilution and whole genome sequencing at a central laboratory. Multivariate logistic regression was performed to account for confounders. Absolute risk increase for 30-day mortality between treatment groups was calculated for the primary analysis (PA) and the microbiologic assessable (MA) populations.

RESULTS

320 isolates from 379 enrolled patients were available with susceptibility to piperacillin/tazobactam 94% and meropenem 100%. The piperacillin/tazobactam non-susceptible breakpoint (MIC > 16 mg/L) best predicted 30-day mortality after accounting for confounders (odds ratio 14.9, 95% CI 2.8 - 87.2). The absolute risk increase for 30-day mortality for patients treated with piperacillin/tazobactam compared with meropenem was 9% (95% CI 3% - 15%) and 8% (95% CI 2% - 15%) for the original PA population and the post-hoc MA populations, which reduced to 5% (95% CI -1% - 10%) after excluding strains with piperacillin/tazobactam MIC values > 16 mg/L. Isolates co-harboring ESBL and OXA-1 genes were associated with elevated piperacillin/tazobactam MICs and the highest risk increase in 30-mortality of 14% (95% CI 2% - 28%).

CONCLUSION

After excluding non-susceptible strains, the 30-day mortality difference was from the MERINO trial was less pronounced for piperacillin/tazobactam. Poor reliability in susceptibility testing performance for piperacillin/tazobactam and the high prevalence of OXA co-harboring ESBLs suggests meropenem remains the preferred choice for definitive treatment of ceftriaxone non-susceptible E. coli and Klebsiella.

Geometric and Dosimetric Evaluation of a Commercially Available Auto-segmentation Tool for Gross Tumour Volume Delineation in Locally Advanced Non-small Cell Lung Cancer: a Feasibility Study

AIMS

To quantify the reliability of a commercially available auto-segmentation tool in locally advanced non-small cell lung cancer using serial four-dimensional computed tomography (4DCT) scans during conventionally fractionated radiotherapy.

MATERIALS AND METHODS

Eight patients with serial 4DCT scans (n = 44) acquired over the course of radiotherapy were assessed. Each 4DCT had a physician-defined primary tumour manual contour (MC). An auto-contour (AC) and a user-adjusted auto-contour (UA-AC) were created for each scan. Geometric agreement of the AC and the UA-AC to the MC was assessed using the dice similarity coefficient (DSC), the centre of mass (COM) shift from the MC and the structure volume difference from the MC. Bland Altman analysis was carried out to assess agreement between contouring methods. Dosimetric reliability was assessed by comparison of planning target volume dose coverage on the MC and UA-AC. The time trend analysis of the geometric accuracy measures from the initial planning scan through to the final scan for each patient was evaluated using a Wilcoxon signed ranks test to assess the reliability of the UA-AC over the duration of radiotherapy.

RESULTS

User adjustment significantly improved all geometric comparison metrics over the AC alone. Improved agreement was observed in smaller tumours not abutting normal soft tissue and median values for geometric comparisons to the MC for DSC, tumour volume difference and COM offset were 0.80 (range 0.49-0.89), 0.8 cm³ (range 0.0-5.9 cm³) and 0.16 cm (range 0.09-0.69 cm), respectively. There were no significant differences in dose metrics measured from the MC and the UA-AC after Bonferroni correction. Variation in geometric agreement between the MC and the UA-AC were observed over the course of radiotherapy with both DSC (P = 0.035) and COM shift from the MC (ns) worsening. The median tumour volume difference from the MC improved at the later time point.

CONCLUSIONS

These findings suggest that the UA-AC can produce geometrically and dosimetrically acceptable contours for appropriately selected patients with non-small cell lung cancer. Larger studies are required to confirm the findings.

Quantitation of Tebuconazole in Liquid and Solid Formulations by Capillary GC: Collaborative Study

A capillary gas chromatographic method has been developed for quantitation of tebuconazole (Folicur, Elite, Raxil, Lynx) in liquid and solid formulations. Tebuconazole is a broad-spectrum, systemic foliar fungicide used to control diseases of wheat, barley, peanut, and grasses grown for seed. Samples are dissolved in acetone and analyzed by capillary gas chromatography (GC) with dicyclohexyl phthalate as internal standard. Twenty-two laboratories from 11 countries participated in a collaborative study of the method. Each collaborator was provided reference standard, internal standard, and blind duplicate samples from 6 formulations: aqueous flowable (F), aqueous emulsifiable concentrate (EW), emulsifiable concentrate for seed treatment (ES), flowable for seed treatment (FS), wettable powder (WP), and dry flowable (DF). Collaborators were instructed to use peak area measurements for quantitation. The seed treatment flowable formulation required confirmation of accurate integration values by the collaborator. Relative standard deviation values for reproducibility (RSDR) for analysis of the formulations were as follows: 3.6 lb/gal F, 1.22; 250 g/L EW, 1.13; 15 g/L ES, 2.40; 25 g/L FS, 2.65; 25% WP, 0.96; 25% DF, 0.72; 45% DF, 0.72. The capillary GC method for quantitation of tebuconazole in fungicide formulations has been adopted first action by AOAC INTERNATIONAL.

Differential Relapse Patterns for Non-small Cell Lung Cancer Subtypes Adenocarcinoma and Squamous Cell Carcinoma: Implications for Radiation Oncology

AIMS

Curative-intent (radical) radiotherapy aims to control local disease and cure non-small cell lung cancer (NSCLC). The predominant subtypes of NSCLC are adenocarcinoma and squamous cell carcinoma (SCC). The radiotherapy paradigm offered to patients does not differ according to these two subtypes. Relapse patterns and disease control rates for adenocarcinoma and SCC treated with radical radiotherapy were determined.

MATERIALS AND METHODS

A radical radiotherapy database covering the period from 2004 to June 2016 was examined to determine the first sites of relapse and the actuarial local and distant control rates.

RESULTS

In total, 537 patients with known pathological subtype were treated over the period. In 39 (7%), the site of first relapse was uncertain. Of the remainder, 203 (41%) had adenocarcinoma and 295 (59%) had SCC. At a median follow-up of 16.4 months, 58% had relapsed. There was a difference in relapse patterns (chi-squared test P < 0.0005), with a higher rate of first relapse locally in SCC (42% of all patients versus 24%) and a higher rate of first relapse in the brain for adenocarcinoma (14% versus 3%). The actuarial local control rate was worse for SCC (hazard ratio 0.6, 95% confidence interval 0.5-0.9, P = 0.002). The brain metastasis-free survival was worse for adenocarcinoma (hazard ratio 4.1, 95% confidence interval 2.2-7.5, P < 0.0001).

CONCLUSION

There is a difference in relapse patterns between NSCLC histological subtypes, indicating that these are distinct entities. This may have implications for follow-up policy and strategies to improve disease control.

Neurotoxicity from immune-checkpoint inhibition in the treatment of melanoma: a single centre experience and review of the literature

Background

Treatment with immune checkpoint inhibitors (ICPi) has greatly improved survival for patients with advanced melanoma in recent years. Anti-CTLA-4 and anti-PD1 antibodies have been approved following large Phase III trials. Immune-related neurological toxicity of varying severity has been reported in the literature. The cumulative incidence of neurotoxicity among ipilimumab, nivolumab and pembrolizumab is reported as <1% in published clinical trials. We aimed to identify the incidence of neurotoxicity in our institution across anti-CTLA4 and anti-PD-1 antibodies, including the combination of ipilimumab with nivolumab. We also review the existing literature and propose an investigation and management algorithm.

Methods

All patients with advanced melanoma treated with ipilimumab, nivolumab, pembrolizumab or the combination of ipilimumab and nivolumab (ipi + nivo), managed at the Royal Marsden Hospital between September 2010 and December 2015, including patients on (published) clinical trials were included. Medical records for each patient were reviewed and information on neurotoxicity recorded. A systematic search strategy was performed to collate existing reports of neurological toxicity.

Results

In total, 413 immunotherapy treatment episodes in 352 patients were included, with median follow-up of 26.7 months. Ten cases of neurotoxicity were recorded, affecting 2.8% of patients overall, ranging from grade 1 to 4, affecting both central and peripheral nervous systems. A rate of 14% was noted with ipi + nivo. Three of five patients commenced on corticosteroids responded to these. Six patients had made a full recovery at the time of reporting. A favorable radiological response was found in 7 of the 10 cases. Unusual presentations are described in detail.

Conclusions

Neurological toxicity is not uncommon, and may be more frequent in patients treated with combination ipi + nivo. Patterns of presentation and response to treatment are varied. A prompt and considered approach is required to optimize outcomes in this group of patients.

Cardiotoxicity Following Cancer Treatment

More than half of those born after 1960 will develop cancer during their lifetime. Fortunately, owing to improved diagnosis and treatment, cure rates have risen steadily over the last three decades. With an increased survivorship, more will experience adverse effects of cancer therapeutics on the heart. As the oncologist's focus begins to encompass the issues of cancer survivorship, awareness of the management of cardiac toxicity would be prudent for all physicians looking after patients with cancer.