"We chose 3-year disease-free survival as our primary end point because most relapses in gastric cancer occur within 2 or 3 years, and the survival after relapse is around 1 year," he commented. "In addition, there is evidence that 3-year disease-free survival is a surrogate end point for 5-year overall survival."
The patients had a median age of about 56 years, and 71% were male. The median time between surgery and randomization was 1.12 months.
At the trial’s preplanned interim analysis, the median follow-up was 34.4 months. The median number of cycles of therapy received was eight for both capecitabine and oxaliplatin. The median dose intensity was 85% and 98%, respectively.
"The safety of adjuvant XELOX in gastric cancer was consistent with the known safety profile of XELOX, with no new or unexpected findings," Dr. Bang reported. The rate of grade 3/4 adverse events was 54% in the XELOX arm and 6% in the observation arm. Two patients in the former arm died of treatment-related causes.
In intention-to-treat analyses, the 3-year rate of disease-free survival benefit was apparent. "The two curves separated early and the difference was well maintained," he commented.
In subgroup analyses, hazard ratios consistently favored XELOX. Analyses according to histologic tumor type are still ongoing, but HER2 testing was not done in the study.
There was also a trend toward a better 3-year rate of overall survival with XELOX (HR, 0.74; P = .0775). "The overall survival curves started to separate at 24 months; however, at this time point, the data are not mature enough," he said. "Longer follow-up is needed to determine the effect of adjuvant XELOX on overall survival."
The trial was sponsored by Sanofi-Aventis and Roche. Dr. Bang reported that he is a consultant to and receives honoraria from Roche. Dr. Lordick reported that he is a consultant to Amgen and Ganymed; receives honoraria from Amgen, Fresenius, Merck Serono, Pfizer, and Roche; and receives research funding from Fresenius, GlaxoSmithKline, Merck Serono, and Sanofi-Aventis.