1463PPrognostic and predictive value of 18F-PET/CT on the response to treatment in locally advanced non-small cell lung cancer (NSCLC)

Abstract Background PET/CT is an essential component in the initial assessment of locally advanced NSCLC. However, the role of PET/CT in the assessment of response to therapies is not well established. Methods We reviewed all stage III NSCLC patients assessed at our centre between January 2009 and March 2018, selecting those with PET/CT evaluation at diagnosis and after treatment (chemotherapy and/or radiotherapy). We evaluated the prognostic differences between mayor PET/CT response (reduction of ≥ 50% of initial SUVmax), minor PET response (reduction of Results We reviewed 249 patients. In 92,3% an initial PET/CT evaluation was carried out. 117 patients (46.9%) had a PET/CT re-evaluation after an initial chemotherapy and/or radiotherapy treatment. We observed a higher risk of disease progression in patients with a minor PET/CT response (HR 1.97; IC95% 1.2-3.2) and without a response (HR 2.3; IC95% 1.4-4.6, p 2.5 presented a sensitivity of only 42.9% and a specificity of 87.5%. Conclusions PET/CT response after induction therapy was a good prognosticator for PFS and OS in stage III NSCLC patients. However, response evaluation by PET/CT should be interpreted with caution due to its lack of precision. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure V. Calvo de Juan: Honoraria (self): BMS; Honoraria (self): MSD; Honoraria (self): AstraZeneca; Honoraria (self): Boerhinger; Honoraria (self): Roche. M. Provencio: Honoraria (self), Research grant / Funding (institution): BMS; Honoraria (self): MSD; Honoraria (self): AstraZeneca; Honoraria (self), Research grant / Funding (institution): Boerhinger. All other authors have declared no conflicts of interest.