LAUSR

302 Background: The majority of esophageal and gastric cancers are diagnosed at an advanced stage with poor overall survival (OS), leading some to propose screening, even in countries with a low incidence. Whether diagnostic delay from symptom onset has any impact on OS is unclear. We investigated this question in the peri-COVID19 pandemic era. Methods: We retrospectively analyzed a cohort of 308 patients with esophageal, gastroesophageal junction, or gastric carcinoma treated with curative intent at the Princess Margaret Cancer Centre from January 2017 to December 2021. Clinical details pertaining to the initial presentation were determined through a retrospective chart review. OS was estimated using the Kaplan-Meier method. Cox proportional hazards regression models were used to assess the association between pre-diagnostic interval with OS adjusting for baseline patient characteristics. Results: The median interval from symptom onset to diagnosis was 98 days (IQR 47-169 days). Using a cox proportional hazard model, prolonged pre-diagnostic interval was not associated with worse OS (HR 1.00, P=0.62). Comparing patients diagnosed before and during the COVID19 pandemic, there was a notable increase in diagnostic delay with median pre-diagnostic interval increasing from 92 to 126 days (P=0.007). Median age at time of diagnosis was 69.6 during the pandemic vs 64.7 before the pandemic. Linear regression showed squamous cell histology was significantly associated with increasing time to initial diagnosis (P=0.04). Looking at other delay metrics, there were no changes in time interval from diagnosis to treatment during versus before the pandemic (median = 1.7 weeks for both), and there was no change in time from diagnosis to resection in those patients who underwent surgery. Conclusions: The COVID19 pandemic caused significant diagnostic delay for patients presenting with curative esophageal and gastric cancer. We found no evidence of pandemic-related health system delays in treatment, once a diagnosis was made. The lack of correlation of pre-diagnostic interval with OS may reflect underlying tumour biology as the driving force that determines prognosis.