Prognostic significance of post-treatment standardized uptake value (pSUV) of positron emission tomography (PET) to predict overall survival (OS) and relapse-free survival (RFS) in patients with esophageal or gastroesophageal cancer treated with definitive chemoradiotherapy.

Abstract

4055 Background: The value of PET after definitive chemoradiotherapy is still unclear. We hypothesized that the post-treatment pSUV and the percentage decrease SUV from baseline (dSUV) would correlate with patient outcome. Methods: We performed retrospective study, selecting patients with advanced E-GEC who had pre- and post-treatment PET, endoscopic ultrasonography (EUS) and were treated with definitive chemoradiation at MD Anderson Cancer Center between 2002 to early 2008. Correlations were performed between clinical variables, pSUV, and dSUV. Results: We analyzed 209 consecutive E-GEC patients treated with definitive chemoradiation for outcome; of these 180 had baseline PET and 161 had post-treatment PET performed 5 to 6 weeks after the completion of definitive chemoradiotherapy for additional analyses. The median OS and relapse free survival (RFS) for all patients was 20.7 months (95% CI; 18.8 to 26.3) and 11.2 months (95% CI; 9.44 to 14.34). Patients with clinical complete response (cCR, 68.9%) which assessed by EUS, PET and clinical parameters lived longer than those not achieving a cCR (P < 0.001). The median pSUV and dSUV were 4.3 (range, 0 to 19.9) and 76.85% (range -177 to 100), respectively. In the univariate analysis, continuous pSUV and dichotomized pSUV cut off by median were associated with OS (Cox model, P = 0.01; log-rank test, P = 0.01) and RFS (Cox model P=0.0004, log-rank test, P = 0.0004). In the multivariate model, continuous pSUV was an independent prognosticator of OS (p = 0.003) and RFS (p < 0.001). dSUV were not associated with OS (P = 0.096) and RFS (P = 0.082) in the univariate analysis. Conclusions: The higher SUV after chemoradiotherapy, the poorer are OS and RFS of gastroesophageal cancer patients treated with definitive chemoradiotherapy. Post chemoradiation PET may become useful in guiding individualized therapy.