Reduction in Tumor Volume by Cone Beam Computed Tomography Predicts Overall Survival in Non-Small Cell Lung Cancer Treated With Chemoradiation Therapy

Abstract

Purpose We sought to evaluate whether tumor response using cone beam computed tomography (CBCT) performed as part of the routine care during chemoradiation therapy (CRT) could forecast the outcome of unresectable, locally advanced, non-small cell lung cancer (NSCLC). Methods and Materials We manually delineated primary tumor volumes (TV) of patients with NSCLC who were treated with radical CRT on days 1, 8, 15, 22, 29, 36, and 43 on CBCTs obtained as part of the standard radiation treatment course. Percentage reductions in TV were calculated and then correlated to survival and pattern of recurrence using Cox proportional hazard models. Clinical information including histologic subtype was also considered in the study of such associations. Results We evaluated 38 patients with a median follow-up time of 23.4 months. The median TV reduction was 39.3% (range, 7.3%-69.3%) from day 1 (D1) to day 43 (D43) CBCTs. Overall survival was associated with TV reduction from D1 to D43 (hazard ratio [HR] 0.557, 95% CI 0.39–0.79, P=.0009). For every 10% decrease in TV from D1 to D43, the risk of death decreased by 44.3%. For patients whose TV decreased ≤39.3 or <39.3%, log-rank test demonstrated a separation in survival (P=.02), with median survivals of 31 months versus 10 months, respectively. Neither local recurrence (HR 0.791, 95% CI 0.51–1.23, P=.29), nor distant recurrence (HR 0.78, 95% CI 0.57–1.08, P=.137) correlated with TV decrease from D1 to D43. Histologic subtype showed no impact on our findings. Conclusions TV reduction as determined by CBCT during CRT as part of routine care predicts post-CRT survival. Such knowledge may justify intensification of RT or application of additional therapies. Assessment of genomic characteristics of these tumors may permit a better understanding of behavior or prediction of therapeutic outcomes.

Cone-beam computed tomography in lung stereotactic ablative radiation therapy: predictive parameters of early response

“…Another potential application of CBCT could be the ability to assess tumour volume changes during RT. 16,17 The issue of tumour volume reduction during conventional RT is well recognized in the scenario of adaptive strategy in head and neck cancer. In fact, this topic was largely investigated to minimize healthy tissue toxicity, focalizing the high dose to a smaller tumour volume.…”

“…[27][28][29][30][31] Concerning lung RT, in a small series of 38 patients affected by unresectable NSCLC and treated with concomitant chemo-conventional RT, tumour volume response evaluated by means of weekly CBCT was associated with a longer OS. 17 Unfortunately, no measured CBCT cut-off tumour response was determined for a better understanding of the behaviour or prediction of therapeutic outcomes. Conversely, Brink et al 32 showed a rather controversial result that greater tumour reduction during RT is unfavourable in terms of locoregional control and OS for nonadenocarcinoma histologies, supposing that the rapid tumour shrinkage during RT could be an indicator of tumour aggressiveness (in terms of high kinetic proliferative).…”

Cone‐beam CT radiomics features might improve the prediction of lung toxicity after SBRT in stage I NSCLC patients

“…Previous studies found that changes in tumor density and volume obtained from CBCT images predicted treatment response to chemoradiation therapy in advanced NSCLC patients. A reduction in tumor volume on CBCT during definitive chemoradiotherapy correlated with improved disease control and overall survival of stage III–IV non‐small cell lung cancer patients . These studies have reported inconsistent time points, CBCT‐measured tumor volumes and/or density changes associated with the clinical outcomes.…”

“…These images can provide data on the day‐to‐day changes of the tumor and normal tissue during the course of irradiation . Previous studies have shown that tumor volume reduction and CT number changes in CBCT images could potentially predict the treatment response for lung cancer . However, these findings were inconsistent and inconclusive.…”

Image guided radiation therapy may result in improved local control in locally advanced lung cancer patients

“…IGRT can be employed to track tumor volumes throughout treatment, which can have implications for overall survival. 17,18 Adaptive radiotherapy, which utilizes IGRT to evaluate throughout therapy with the potential to shrink field sizes, is dependent on IGRT and is aimed towards improving the therapeutic ratio for these patients. These strategies depend on the principle that proper identification of the target improves local control, which is supported by this study.…”