PET produces early measure of response to chemotherapy for esophagogastric junction cancer

A German study has found that FDG PET can differentiate between responders and nonresponders two weeks after the initiation of neoadjuvant chemotherapy for advanced adenocarcinoma of the esophagogastric junction.

"This is the first study to apply PET results from early metabolic response assessment to clinical decision-making in the treatment of common solid tumors," said Dr. Ken Herrmann, a resident in the nuclear medicine department at the Technical University in Munich. The study was initiated by Dr. Florian Lordick in the university's surgery department. Results were presented in June at the 2007 Society of Nuclear Medicine meeting.

F-18 FDG PET was performed on 110 patients with potentially R0 resectable adenocarcinoma of the esophagogastric junction to assess for metabolic response.

Patients with a greater than 35% decrease in tumor standardized uptake value (SUV) after two weeks of neoadjuvant platin/5-fluorouracil-based chemotherapy compared with baseline were defined as metabolic responders. They continued on chemotherapy for 12 weeks before surgery.

Patients with less than a 35% SUV decrease were classified as metabolic nonresponders. Chemotherapy was stopped after the initial two weeks for nonresponders, and they proceeded to immediate surgery. Follow-up CT scans and endoscopy were performed every three months in the first year and every six months thereafter.

The overall response rate after two weeks of the chemotherapy was 49%. A total of 104 patients underwent resection (subtotal esophagectomy 70%, extended gastrectomy 30%).

Major histologic remissions (less than 10% residual tumor) were observed in 58% of metabolic responders versus none for the metabolic nonresponders (P

After a median follow-up of 2.3 years, metabolic responders have obtained a significantly better median event-free survival of 29.7 months versus 14.1 months for metabolic nonresponders (P

"The outcome for metabolic responders turned out to be remarkably favorable, compared with metabolic nonresponders," Herrmann said.

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