A prospective study, MUNICON II, has shown that detecting early metabolic response to chemotherapy by positron emission tomography (PET) imaging prior to surgery is useful in determining a patient?s prognosis for locally advanced adenocarcinoma of the esophagogastric junction. Researchers also found that those who did not respond to chemotherapy did not benefit from additional radiation. The study results were presented during the eighth annual Gastrointestinal Cancers Symposium, which will be held January 20-22, 2011, at The Moscone West Building in San Francisco.
?We confirmed that PET testing after two weeks of chemotherapy is a very important prognostic tool. This approach can help a physician distinguish patients who are responding to chemotherapy from those who are not, and who can therefore be spared from the unnecessary toxicities of treatment that is unlikely to improve their outcome,? said lead researcher Florian Lordick, MD, PhD, Director of the Department of Hematology and Oncology at Klinikum Braunschweig in Brunswick, Germany, and senior lecturer at Hannover Medical School.
Earlier studies have shown that using PET imaging with fluorodeoxyglucose (FDG) can help detect response to chemotherapy given prior to surgery to shrink tumors in patients with locally advanced adenocarcinoma of the esophagogastric junction. Tumors accumulate glucose as a result of increased proliferation and glucose demand. FDG-PET can detect the glucose uptake in tumor tissue. When tumors are treated successfully with chemotherapy, a sharp decrease in glucose uptake in the tumor can be seen and measured by PET. If the tumor is not sensitive to chemotherapy and continues to grow, no change in PET imaging will be observed.
In the study, 56 patients with locally advanced esophagogastric cancer were divided into responders and non-responders on the basis of PET results after two weeks of chemotherapy. For patients who had a metabolic response, treatment continued for three additional months before surgery. For those without a PET response early during chemotherapy, therapy was changed and radiation was given before surgery to reduce the tumor size and increase the likelihood of completely removing the cancer.
There were 33 patients who responded to chemotherapy and 23 patients who did not, as measured by PET. Of the 33 responders, 27 (82%) patients were able to undergo curative surgery (surgery to remove all evidence of disease) compared to 16 (70%) of the non-responders. After a median follow-up time of 38 months, the median event-free survival and median overall survival of the non-responders were 15.4 months and 18.3 months, respectively. The responders had yet to reach median event-free survival and median overall survival after 38 months.
While PET can be used to guide treatment in other cancers, such as lymphoma and lung cancer, Dr. Lordick believes this is the first attempt to implement treatment changes on the basis of early PET findings.
?What?s unfortunate is that the results of our study also indicate that for early metabolic non-responders, there is not yet an effective salvage treatment that could improve their poor prognosis. We?re continuing to look for more effective ways to treat this group of patients,? Dr. Lordick said. Next, the researchers plan to confirm the prognostic and predictive value of PET in a randomized, multicenter, multinational trial called IMAGE. In addition, they will look for new treatment approaches for those patients who have poor prognoses based on the lack of early metabolic responses in chemotherapy.
For more information:
Lordick F, Meyer Zum Bueschenfelde C, Herrmann K, Geinitz H, Schuster T, et al. PET-guided treatment in locally advanced adenocarcinoma of the esophagogastric junction (AEG): The MUNICON-II study. Abstract #3