Klin Onkol 2021; 34(2): 113-119. DOI: 10.48095/ccko2021113.
Background: Preoperative chemoradiotherapy (CRT) and perioperative chemotherapy (CHMT) are a standard of care for distal esophageal and gastroesophageal junction adenocarcinomas. PET/CT using 18F-fluorodeoxyglucose (18F-FDG-PET/CT) is one of the basic staging examinations with a certain prognostic significance and has recently been studied for the possibility of showing prognostic or predictive results suitable for the individualization of treatment strategy. Purpose: The aim of this review is to map the role of 18-FDG-PET/CT in predicting the response to CHMT and CRT, which could be a starting point for personalized treatment. Content: The change in metabolic activity in the maximum standardized uptake value is most often used to quantify the treatment response; total lesion glycolysis is a volumetric parameter. A method for standardizing measurements was offered in the PERCIST system. Several studies have been published showing that the decrease in metabolic activity after chemotherapy correlates with a surrogate measure of the treatment outcome, which is the degree of tumor regression in the resected tissue, but also with survival or time to progression. The cut-off value separating sensitive and resistant tumors varied from 33 to 78%, the measurement took place either at the end of neoadjuvant treatment or „early“, about 2 weeks after the first cycle of CHMT. However, this value has not yet been validated and the parameters of sensitivity, specificity and negative and positive predictive values for the prediction of treatment outcome fluctuated significantly. In the case of preoperative CRT, PET/CT could not predict the complete response to the treatment with satisfactory accuracy. Studies using early metabolic response to change the treatment strategies in non-responders have not yet shown whether changing the treatment in patients without an early metabolic response to CHMT will improve survival. In the case of randomization, a standard arm with a continuation of the original CHMT was never used. Conclusion: Evaluation of an early PET-based response has the potential to modify the treatment in patients who have not demonstrated an early response to CHMT. However, this is not an approach suitable for routine practice outside of clinical trials. So far, it seems possible to use an early metabolic response for small, exploratory studies evaluating new agents and their combinations in the preoperative treatment of localized esophageal cancer or gastroesophageal junction cancer.
