Prognostic potential of initial CT changes for progression-free survival in gefitinib-treated patients with advanced adenocarcinoma of the lung: a preliminary analysis

Objectives: We aimed to determine whether initial tumour responses measured during short-term follow-up computed tomography (CT) examinations after baseline examinations would correlate with clinical outcomes in patients with non-small cell lung cancer (NSCLC) who received epidermal growth factor receptor (EGFR)-targeted therapy. Methods: A total of 86 gefitinib-treated patients with advanced adenocarcinoma of the lung were retrospectively reviewed. All patients underwent baseline and short-term follow-up CT examinations. The new response criteria (NRC) by Lee et al. were used for the response evaluations. A Cox proportional hazards multiple regression model and Kaplan–Meier survival analyses were used to evaluate correlations between the initial tumour changes and progression-free and overall survival (PFS, OS). Results: Better separation and smaller p values were observed for both PFS and OS when good and poor disease responses (as defined by NRC) were compared after excluding tumours with characteristic morphologies. Early tumour changes correlated with PFS in a size-dependent manner. Moreover, a stronger association was observed between size changes and PFS when characteristic morphology was also considered. Conclusions: Initial changes in tumour size during short-term post-treatment CT examinations could act as a potential prognostic imaging surrogate for PFS in gefitinib-treated patients with advanced adenocarcinoma of the lung. Key points: • Initial responses to gefitinib on computed tomography significantly correlate with clinical outcomes. • Regardless of morphology, size decrease greater than 30 % predicts prolonged progression-free and overall survival. • Combination of size and morphological changes yields prognostic independence regarding progression-free survival.