Prognostic and Predictive Value of FDG-PET as an Aid in Oesophageal Cancer Management

18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is widely used for cancer staging before treatment and detection of recurrence during post-treatment surveillance. It is increasingly being recognised that tumour FDG uptake values may not only be prognostic, but could have predictive value to assess for treatment response during and after neoadjuvant therapy in oesophageal cancer (OC). This review focusses on the available evidence concerning the prognostic or predictive role of FDG-PET and evaluates the potential value of FDG-PET in guiding treatment decisions in OC. The correlation between pretreatment maximum standardised uptake value (SUVmax) and prognosis has been demonstrated by multiple studies, although the results are inconsistent and sometimes conflicting. With regard to the predictive value for FDG-PET, post-SUVmax after neoadjuvant chemotherapy appears to hold better promise compared to chemoradiotherapy due to the confounding effect of radiation oesophagitis. Since a number of studies have demonstrated that FDG-PET can discriminate responders from non-responders to induction chemotherapy, the predictive value of FDG-PET imaging was evaluated prospectively and the initial results of CALGB 80803 suggested that changing chemotherapy regimen based on FDG-PET response to induction chemotherapy may improve pathologic complete response rate in PET non-responders when an alternative chemotherapy is used. Furthermore, additional research has suggested that FDG-PET response after induction chemotherapy or neoadjuvant chemotherapy may enrich a patient subset who may potentially avoid subsequent surgery after chemoradiotherapy. However, the majority of reports published on FDG-PET in OC are limited to small, retrospective, and single-institutional studies. Therefore, much of the current evidence-to-date is still hypothesis-generating and would require vigorous validation before FDG-PET could become part of routine clinical practice to direct treatment decisions.