The role of qualitative and quantitative analysis of F18-FDG positron emission tomography in predicting pathologic response following chemoradiotherapy in patients with esophageal carcinoma.

OBJECTIVE: The aim of this study was to determine if a qualitative and quantitative assessment of pre- and post-chemoradiotherapy (CRT) F18-FDG PET scans of esophageal cancer patients could predict for residual disease in esophagectomy specimens.

METHODS: We retrospectively reviewed the records of esophageal cancer patients who had undergone CRT at a single institution. Analysis was limited to esophagectomy patients with both pre- and post-CRT F18-FDG PET scans. The maximum standardized uptake value (SUV), location, and measured length of esophagus with increased F18-FDG uptake were obtained from the PET scan before and 3-4 weeks following CRT (preoperatively). The pattern of F18-FDG uptake was qualitatively assigned a category of diffuse, focal, or diffuse with focal component.

RESULTS: Fifty-seven patients with localized esophageal carcinoma underwent F18-FDG PET/CT scans as part of their initial staging and post-CRT restaging workup, followed by esophagectomy. The pathologic complete response (pCR) rate was 25%. The presence of a focal component on post-CRT PET predicted residual disease on univariate analysis (86% vs. 64%), and achieved significance when controlling for SUV and presence of diabetes on MVA (OR = 5.59, p = 0.028). There was no significant relationship between pre- or post-CRT SUV, tumor histology, or length of increased F18-FDG uptake and presence of residual disease. SUV and focality did not interact significantly to predict residual disease.

CONCLUSIONS: Qualitative but not quantitative PET imaging can help predict increased likelihood of residual tumor in esophageal cancer patients following CRT; however, it is not sensitive enough to solely rule out the presence of residual disease. Additional investigation with a larger cohort of patients is warranted.