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.

Is community treatment best? a randomised trial comparing delivery of cancer treatment in the hospital, home and GP surgery

BACKGROUND

Care closer to home is being explored as a means of improving patient experience as well as efficiency in terms of cost savings. Evidence that community cancer services improve care quality and/or generate cost savings is currently limited. A randomised study was undertaken to compare delivery of cancer treatment in the hospital with two different community settings.

METHODS

Ninety-seven patients being offered outpatient-based cancer treatment were randomised to treatment delivered in a hospital day unit, at the patient's home or in local general practice (GP) surgeries. The primary outcome was patient-perceived benefits, using the emotional function domain of the EORTC quality of life (QOL) QLQC30 questionnaire evaluated after 12 weeks. Secondary outcomes included additional QOL measures, patient satisfaction, safety and health economics.

RESULTS

There was no statistically significant QOL difference between treatment in the combined community locations relative to hospital (difference of -7.2, 95% confidence interval: -19·5 to +5·2, P=0.25). There was a significant difference between the two community locations in favour of home (+15·2, 1·3 to 29·1, P=0.033). Hospital anxiety and depression scale scores were consistent with the primary outcome measure. There was no evidence that community treatment compromised patient safety and no significant difference between treatment arms in terms of overall costs or Quality Adjusted Life Year. Seventy-eight percent of patients expressed satisfaction with their treatment whatever their location, whereas 57% of patients preferred future treatment to continue at the hospital, 81% at GP surgeries and 90% at home. Although initial pre-trial interviews revealed concerns among health-care professionals and some patients regarding community treatment, opinions were largely more favourable in post-trial interviews.

INTERPRETATION

Patient QOL favours delivering cancer treatment in the home rather than GP surgeries. Nevertheless, both community settings were acceptable to and preferred by patients compared with hospital, were safe, with no detrimental impact on overall health-care costs.