PET scans used to assess tumor response to initial chemotherapy allowed clinicians to tailor additional treatments for patients with esophageal cancer, leading to an improvement in pathologic complete response rates, according to results of a federally funded clinical trial scheduled for presentation at the Gastrointestinal Cancers Symposium.
Results showed nearly a 10-percentage point increase in complete response rates for patients who switched to an alternative chemotherapy following a PET scan compared with historical data.
“Our study showed the benefit of a new paradigm using metabolic imaging in esophageal and gastroesophageal (GE) junction cancers to individualize multimodality therapy and improve outcomes in this poor prognosis population,” Karyn A. Goodman, MD, MS, radiation oncologist at University of Colorado School of Medicine, said during a press conference. “Going forward, early response assessment using PET imaging can be incorporated into future studies to identify more effective new regimes for esophageal and GE junction cancers.”
Karyn A. Goodman
Worldwide, an estimated 400,000 people die of esophageal cancer every year. In the United States, approximately 17,000 people were diagnosed with this cancer in 2016 and 16,000 died of the disease, which carries less than a 50% survival rate 5 years after diagnosis.
Patients with stage 2 and stage 3 esophageal and GE junction cancers typically receive 5.5 weeks of chemotherapy with radiation, followed by surgery.
Researchers hoped to improve pathologic response rates from 5% to 20% by using PET scans to provide more personalized chemoradiation treatments. PET scans — covered by Medicare — are routinely used to guide therapy decisions in lymphoma and are just beginning to see use in the management of solid tumors.
Following an initial PET scan, researchers randomly assigned 257 patients with stage 2 or stage 3 esophageal and GE junction adenocarcinoma to one of two induction chemotherapy regimens — modified FOLFOX-6 (oxaliplatin, leucovorin and 5-FU) on days 1, 15 and 29 (n = 129), or carboplatin/paclitaxel on days 1, 8, 22 and 29 (n = 128). Patients also underwent surgery 6 weeks post-chemoradiation.
Patients underwent a repeat PET scan between days 36 and 42, after which researchers assessed changes in max standardized uptake value. Researchers defined PET responders as those with at least a 35% decrease in standardized uptake value.
If PET scans showed cancer regression, patients continued with the same chemotherapy treatments. Conversely, patients who did not respond were switched to the other of the two regimens.
Overall, 39 of the patients who received FOLFOX-6 and 49 of the patients who received carboplatin/paclitaxel switched regimens after the PET scan.
Among the patients who switched treatments, 15.6% (95% CI, 0.08-0.26) ultimately achieved pathologic complete response, an increase over the 5% complete response in prior studies that did not use PET scans to determine a change in therapy.
“I think this really helps move the field forward in terms of finding personalized ways of better treating our patients,” said Nancy Baxter, MD, FRCSC, FACS, PhD, an ASCO gastrointestinal cancer expert who was not involved with the study, “particularly to those who are responding poorly to the therapy we’ve initially offered them and to people who have been diagnosed with these very, very hard-to-treat cancers.”
Goodman said OS data from the study are still maturing and will be reported at a later date.
“We do know from prior studies that pathologic complete response rates do correlate with survival outcomes, and that is why we used this as an intermediate endpoint,” she said. “We will be reporting secondary endpoints in the next 6 months, but we know this is a prognostic marker.” – by Chuck Gormley
Goodman, et al. Abstract CALGB 80803. Scheduled for presentation at: Gastrointestinal Cancers Symposium; Jan. 19-21, 2017; San Francisco.
Disclosure: The study was supported by grants from the NIH. Goodman reports a consultant/advisory role with Pfizer. Please see the abstract for a list of all other researchers’ relevant financial disclosures.