Positron emission tomography imaging for gastroesophageal junction tumors.

Positron emission tomography (PET) is now widely used in the initial evaluation of esophageal and gastroesophageal junction tumors. It can detect otherwise occult metastases, affecting staging and treatment in a significant proportion of patients. The intensity of PET uptake before treatment has been correlated with outcomes, but it remains uncertain whether PET is an independent prognostic factor for survival. An emerging application for PET is the assessment of response to induction chemotherapy or chemoradiotherapy. In particular, PET has the ability to discriminate treatment responders from nonresponders early in the course of induction chemotherapy. This can form the basis for further treatment decisions, such as a change in chemotherapy or the addition of concurrent radiotherapy, and this approach is now being tested in prospective trials. PET after concurrent chemoradiotherapy may also provide information regarding the utility of surgical resection. PET data can affect radiotherapy target definition, which may lead to improved tumor coverage in cases where the true extent of disease is not accurately reflected by computed tomography or endoscopic imaging.