A PET-guided treatment algorithm was proven feasible, according to the results of the MUNICON II trial, published in this month’s Journal of Nuclear Medicine. However, by comparing the groups of non-responding patients in the current trial and the previous published MUNICON I trial, increased histopathologic response was observed after salvage radiochemotherapy, but the study’s primary endpoint to increase the R0 resection rate was not met.
Previous studies demonstrated that chemotherapy-induced changes in tumor glucose metabolism measured with 18F-FDG PET identify patients who benefit from preoperative chemotherapy and those who do not, according to the authors. The prognosis for chemotherapy metabolic non-responders is poorer than for metabolic responders.
Therefore, Christian Meyer zum Büschenfelde, MD, from the Technische Universität München in Munich, and colleagues initiated this prospective MUNICION (Metabolic response evalUatioN for Individualisation of neoadjuvant Chemotherapy in Esophageal and esophagogastric adeNocarcinoma) II trial to improve the clinical outcome of metabolic non-responders using a salvage neoadjuvant radiochemotherapy.
Specifically, in the MUNICON II trial, neoadjuvant chemotherapy was switched to neoadjuvant radiochemotherapy in metabolic non-responding patients to improve the histopathologic response, R0 resection rate and prognosis of patients with gastroesophageal cancer.
The researchers included 56 patients with locally advanced adenocarcinomas of the esophagogastric junction from Sept. 28, 2005, until Nov. 28, 2008. They assessed the tumor glucose uptake by 18F-FDG PET before chemotherapy and 14 days after initiation of chemotherapy. PET non-responders received salvage neoadjuvant radiochemotherapy, whereas metabolic responders received neoadjuvant chemotherapy for three months before surgery.
According to the authors, 33 patients were metabolic responders and 23 were non-responders. Resection was performed on 54 patients. R0 resection rate was 82 percent in metabolic responders and 70 percent in metabolic non-responders.
Büschenfelde and colleagues observed major histologic remissions in 12 metabolic responders (36 percent) and six non-responders (26 percent). The one-year progression-free rate was 74 percent in PET responders and 57 percent in metabolic non-responders.
The one-year overall survival was comparable between the groups (approximately 80 percent), and two-year overall survival was estimated to be 71 percent in metabolic responders and 42 percent in PET non-responders.
Based on these findings, the researchers concluded that the “prognosis of the subgroup of PET non-responders remains poor, indicating their different tumor biology.
“Salvage neoadjuvant radiochemotherapy in metabolic non-responders leads to local remissions in a considerable number of patients, but was not able to change the clinical course in general because of the systemic disease,” Büschenfelde et al wrote. “Future investigations could address whether the prognosis can be improved by adding other systemically active drugs.”