Imaging in evaluation of response to neo-adjuvant treatment

Adenocarcinoma of the gastroesophageal junction (GEJ) has shown better overall prognosis when treated with neoadjuvant therapy prior to surgery; studies have demonstrated that preoperative administration of these therapies can double the median overall survival in comparison to surgery alone. Even though histology remains the gold standard for the evaluation of treatment response, there is the impelling need of a non-invasive tool which can predict early on patient response; identifying responder or non-responder status during (or even before) neoadjuvant therapy becomes fundamental. The few studies which specifically deal with the role of guideline endorsed computed tomography (CT) in assessing tumor response after neoadjuvant therapy specifically in patients with GEJ carcinoma have been inconclusive. Conventional CT, which evaluates dimensional criteria, and PET, used to assess in vivo metabolic response, currently used for diagnosis and staging may be used in conjunction with quantitative parameters derived from magnetic resonance imaging (MRI) or hybrid systems which reveal different aspects of tumour growth, biology and aid staging. Therefore, the unique characteristics of each modality may provide information to tailor-treatment based on response during neoadjuvant treatment. We provide a brief overview of imaging techniques used in clinical practice to evaluate GEJ tumor response and the use of radiomics as an additional quantitative diagnostic tool.