OA24.02 Locally Advanced Non-Small Cell Lung Cancer: RadioTherapy with Adaptive Strategy (LARTIA Trial)

Abstract

Anatomical change of tumor contour during radiotherapy contributes to target missing. Adaptation of tumor volume could however result in an increased incidence of recurrences in the area of target reduction. This study aims to investigate the incidence of failure of adaptive approach in evaluating the risk of local recurrence in the area excluded during replanning. In this prospective study, LA-NSCLC patients treated with concomitant chemoradiation underwent weekly chest-CT simulation during therapy. In case of tumor shrinkage, a new tumor volume (TV) was delineated and a new treatment plan outlined (replanning). Patterns of failure were classified as: in field (persistence or recurrence in TV post-replanning), marginal (recurrence in the area of initial TV excluded from the post-replanning TV) and out of field (recurrence outside of initial TV). Toxicity, OS, and PFS were reported. A total of 217 NSCLC patients were treated in our center from 2012 to 2014. In 50 cases a target volume reduction was recorded and replanning outlined. A mean initial and replanning CTV of 154.9cc and 90.7cc were reported with an average CTV shrinkage of 42% between simulation CT and replanning CT. With a median follow-up of 20.5 months, 30% of patients experienced local failure which was in field, marginal and out of filed in 20%, 6% and 4% of cases respectively. Acute G3 pulmonary and esophageal toxicity was reported in 2% and 4% of patients respectively. The possibility to reduce toxicity and the documented low rate of marginal failures makes the adaptive approach a modern option for future randomized studies. The best scenario to confirm tumor activity is its application in neoadjuvant chemoradiation trials.