A new paradigm to individualize treatment of esophageal and gastroesophageal junction (GEJ) cancers, researchers have shown that positron emission tomography (PET) can help guide chemotherapy decisions for patients and improve outcomes.
Karyn A. Goodman lead author was discussing initial results from the phase 2 CALGB 80803 study at a presscast ahead of the 2017 Gastrointestinal Cancers Symposium in San Francisco, California.
Preoperative chemoradiotherapy is an accepted standard of care for patients with operable esophageal or GEJ adenocarcinoma, but the optimal chemotherapy is undefined, Dr Goodman explained: Several chemotherapy options could be used.
So her team decided to assess chemotherapy responsiveness with PET early on — right after induction therapy, so that another chemotherapy can still be tried during concurrent radiotherapy.
The study was conducted in 257 patients with stage II to III esophageal and GEJ adenocarcinoma, all of whom underwent PET and then were randomly assigned to one of two induction chemotherapy regimens: modified FOLFOX-6 (oxaliplatin, leucovorin, 5-fluoroucil) or carboplatin/paclitaxel.
PET was repeated after the first few cycles of induction therapy. If there was tumor shrinkage as assessed by PET, then patients continued with the same chemotherapy regimen.
However, if the PET scan revealed that the induction chemotherapy regimen was not working, chemotherapy was changed to the other regimen. Overall, 39 of 129 patients who received FOLFOX-6 induction chemotherapy and 49 of 128 patients who received carboplatin/paclitaxel switched chemotherapy regimens after PET.
Overall, this strategy enabled 18.0% of the patients who were initial nonresponders (14 of 78; as assessed by PET) to move on to another chemotherapy regimen and ultimately achieve a pathologic complete response (pCR) upon completion of chemoradiotherapy.
The primary endpoint of the study was pCR (as indicated by PET) among the patients who crossed over to alternative chemotherapy. Overall, the pCR rate was 26.0% among all PET responders (31 of 120) and 22.7% (45 of 198) among all patients who were evaluable in the study.
Dr Goodman pointed out that in prior studies, where presurgery chemotherapy was not changed based on a PET scan, the pCR rate among patients with tumors not responsive to induction chemotherapy was only 5%. In other words, the new results are a substantial improvement over historical outcomes.
Dr Goodman acknowledged that the new approach of using a PET assessment lengthens a patient's time before surgery but emphasized that the results show that the information obtained from the PET scan improves the efficacy of treatment, as shown by the higher pCR rate that was achieved.
PET scans may prove to be a valuable tool to help oncologists fine-tune the use of chemotherapy for esophageal cancer Dr Goodman struck a more convinced note about the usefulness of this strategy.
The new study "shows the benefit of a new paradigm" to individualize multimodality therapy, she said. Further early response assessment using PET can be incorporated into future studies to identify more effective regimens for esophageal and GEJ cancers, she added.