Effects of neoadjuvant radio-chemotherapy on 18F-FDG-PET in esophageal carcinoma

Aim. To investigate whether results of [F-18]-fluorodeoxy-image-glucose (FDG) positron emission tomography (PET) of esophageal cancer (EC) before and after neoadjuvant radio-chemotherapy correlate with histopathology after esophageal resection. Methods. Twenty consecutive patients with EC without distant metastases were examined twice with 18F-FDG-PET during primary staging and after neoadjuvant radio-chemotherapy. FDG standardised uptake values (SUV) were correlated with the histopathological findings (percentage of viable tumour cells, tumour regression grade 1–5). Results. Regression analysis revealed a slight (not significant) positive correlation between SUVpre (R=0.41, p=0.08) and SUVpost (R=0.37, p=0.11) and the percentage of viable tumour cells in the resectate. Although all patients showed a significant decrease in SUV after radio-chemotherapy (p<0.01), the percentual decrease of the SUV after therapy (ΔSUV%) did not significantly differ between the TRG-groups. In 12 of 20 patients (60%), therapy-induced esophagitis was detected in post-therapeutic PET images. Conclusion. In EC, a higher pre-therapeutic SUV might be correlated with a higher fraction of vital tumour cells remaining after radio-chemotherapy. Applying the neoadjuvant therapy protocol and the study design used in this examination, there is no correlation between decrease in SUV and histopathology.