Regional Lung Function Profiles of Stage I and III Lung Cancer Patients: An Evaluation for Functional Avoidance Radiation Therapy

Abstract

Purpose 4DCT-ventilation is an exciting imaging modality that uses 4DCT data to calculate lung function maps. The development of clinical trials is underway to use 4DCT-ventilation imaging to preferentially spare functional lung in patients undergoing radiotherapy. The purpose of this work was to generate data to aide with clinical trial design by retrospectively characterizing dosimetric and functional profiles for patients with different stages of lung cancer disease Methods and Materials A total of 118 lung cancer patients (36% stage I and 64% stage III) from 2 institutions were used for the study. A 4DCT-ventilation map was calculated using the patient’s 4DCT imaging, deformable image registration, and a density-change based algorithm. In order to assess each patient’s spatial ventilation profile both quantitative and qualitative metrics were developed including an observer-based defect observation and metrics based on the ventilation in each lung third. For each patient we used the clinical doses to calculate weighted mean lung doses (fMLD) and metrics that assessed the interplay between the spatial location of the dose and high-functioning lung. Results Both qualitative and quantitative metrics revealed a significant difference in functional profiles between the 2 stage groups (p<0.01). We determined that 65% of stage III and 28% of stage I patients had ventilation defects. Average fMLD was 19.6 Gy and 5.4 Gy for stage III and I patients respectively with both groups containing patients with large spatial overlap between dose and high-function regions. Conclusion Our 118 patient retrospective study found that 65% stage III patients have regionally variant ventilation profiles that are suitable for functional avoidance. Our results suggest that regardless of disease stage, it is possible to have unique spatial interplay between dose and high-functional lung highlighting the importance of evaluating the function of each patient and developing a personalized functional avoidance treatment approach.

4‐Dimensional computed tomography‐based ventilation and compliance images for quantification of radiation‐induced changes in pulmonary function

“…Relatively high heterogeneous lung ventilation profiles were observed in the patients, which is supported by recent literature that stage III lung cancer patients have a more heterogeneous function compared to stage I patients …”

Future cancer research priorities in the USA: a Lancet Oncology Commission

“…262 Finally, four-dimensional CT scanning methods to characterise breathing-related motion for radiotherapy planning could also be applied to derive a quantitative estimate of regional lung function. 263,264 A clinical trial is underway (NCT02528942) to assess the use of this information to avoid unnecessary exposure of highly functional regions of lung during radiotherapy in patients with locally advanced primary lung cancer.…”

Functional Image-guided Radiotherapy Planning for Normal Lung Avoidance

“…Despite this, a large scale study of ventilation defects has been conducted [95] and several attempts have been made to modify lung treatment plans based upon local volume expansion [96 99] or intensity based metrics [33,100,101].…”