The administration of trastuzumab in Canada has increased significantly. Patients’ median survival with trastuzumab in routine practice is much less than observed in a landmark trial. Comparative studies of effectiveness using data offered a new insight into the outcomes achieved in routine medical practice. In the Trastuzumab for Gastric Cancer (ToGA) trial, the median survival in patients improved with advanced gastric and gastroesophageal cancer from 11 to 14 months. This study’s objective was to evaluate the consumption and outcomes of trastuzumab in a population-based cohort of patients with oesophageal, gastroesophageal, and gastric cancer in Ontario, Canada.

The Ontario Cancer Registry and related records were used to identify the patients with cancer mentioned above treated with trastuzumab during 2012–17. The outcomes were analyzed from the first trastuzumab cycle time.  The total number of patients with oesophageal, gastroesophageal, and gastric cancer that received trastuzumab was 476. The mean age among them was 62 years, 78% were male, and 65% had gastric cancer. The average number of cycles of trastuzumab dosage prescribed was six. The 30 days of admission to the hospital and mortality rates were 17% and 4%, respectively.

In conclusion, the survival of patients who were administered trastuzumab for advanced oesophageal, gastroesophageal, and gastric cancer was substantially less than that observed in the pivotal clinical trial.