Predictive value of 18F-FDG PET/CT on survival in locally advanced rectal cancer after neoadjuvant chemoradiation.

ABSTRACT

OBJECTIVE: To evaluate the prognostic value of 18F-FDG PET/CT in terms of survival in patients with locally advanced rectal cancer (LARC) who had undergone surgery preceded by neoadjuvant chemoradiotherapy (nCRT). Moreover, the existence of correlation between Overall Survival (OS) and Disease Free Survival (DFS) with pathological staging ((y)pTNM and TRG) was evaluated. PATIENTS AND METHODS: A total of 58 patients with biopsy-proven of LARC were included. All patients underwent conventional diagnostic/staging procedures to characterize the rectal lesion. The first whole-body 18F-FDG PET/CT was performed 1 week before the beginning of nCRT (baseline scan). The second 18F-FDG PET/CT was scheduled at 5-6 weeks from nCRT completion (post-nCRT scan). Survival was evaluated in 3 different restaging classification systems, based on focusing only on primary lesion (TRG), loco-regional evaluation (ypTNM) and whole-body 18F-FDG PET/CT evaluation (VRA). RESULTS: Among the 58 patients at the end of the observation, 46/58 patients (79.3%) were alive and 12/58 (20.7%) were dead. This work demonstrated a higher percentage of patients with TRG complete response (39.7%) compared to literature (24.6%), with longer Overall Survival (OS) and Disease Free Survival (DFS) in responders even if without statistically significant differences. CONCLUSIONS: The present study highlights the predictive and prognostic potential role of 18F-FDG PET/CT in assisting physicians on personalized decision in the selective risk-adapted treatment strategy, and to schedule the correct follow-up approach.