813P - Increased assessment of HER2 in metastatic gastroesophageal cancer patients: A nationwide population-based cohort study

Abstract

BackgroundAddition of trastuzumab to first-line palliative chemotherapy in esophagogastric cancer patients with HER2 overexpression has shown to improve survival and is therefore considered standard of care. The aim of this study was to assess HER2 testing, trastuzumab administration and overall survival (OS) in a nationwide cohort of metastatic esophagogastric cancer patients. MethodsPatients with synchronous metastatic esophagogastric adenocarcinoma diagnosed between 2010-2016 that received palliative systemic treatment (N=2846) were identified from the Netherlands Cancer Registry. Details on HER2 assessment were extracted from pathology reports from the Dutch Pathology Registry. For determination of HER2 positivity or negativity, the criteria on HER2 assessment of the ToGA trial were used. Proportions of HER2 tested patients were analyzed between hospital volume categories using Chi-square tests, and over time using trend analysis. OS was tested using the Kaplan Meier method and log rank test. ResultsHER2 assessment was performed in 54% of all 2846 patients that received palliative chemotherapy, and increased from 18% to 88% between 2010 and 2016 (P<0.01). Median OS of all patients increased from 6.9 (IQR 3.5-12.0) months in 2010-2013 to 7.9 (IQR 3.6-13.6) months in 2014-2016 (P<0.001). Between the hospitals, the proportion of tested patients varied between 29-100%, and was the highest in high-volume hospitals (P<0.01). HER2 status was positive in 19%, negative in 67% and unknown in 14% of the 1524 tested patients. Overall, 77% of the HER2 positive patients received trastuzumab. Median OS was significantly higher in patients with both positive (8.8 months) and negative (7.4 months) HER2 status that were diagnosed in 2015-2016, compared with non-tested patients (5.6 months; P<0.05). ConclusionsDaily practice management of metastatic esophagogastric cancer patients has changed due to increased determination of HER2 status and administration of trastuzumab, which might have contributed to the improved survival in these patients. Advances in clinical practice could include a further increase in awareness of HER2 testing among pathologists and clinicians, especially in low-volume hospitals, and in the administration of trastuzumab in case of HER2 overexpression. Legal entity responsible for the studyThe authors. FundingRoche. DisclosureR.H.A. Verhoeven: Research grant / Funding (institution): BMS; Research grant / Funding (institution): Roche. N. Haj Mohammad: Advisory / Consultancy: BMS; Advisory / Consultancy: MSD. J. de Vos-Geelen: Non-remunerated activity/ies: BTG; Research grant / Funding (institution), Non-remunerated activity/ies: Servier; Advisory / Consultancy: Shire. T. Van Voorthuizen: Non-remunerated activity/ies: Astellas; Non-remunerated activity/ies: Ipsen; Non-remunerated activity/ies: Roche; Non-remunerated activity/ies: Bayer. M. van Oijen: Research grant / Funding (institution): Roche; Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): Nordic; Research grant / Funding (institution): Servier; Research grant / Funding (institution): Amgen. H.W.M. van Laarhoven: Research grant / Funding (institution): Bayer; Advisory / Consultancy, Research grant / Funding (institution): BMS; Advisory / Consultancy, Research grant / Funding (institution): Celgene; Advisory / Consultancy, Research grant / Funding (institution): Lilly; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): MSD; Advisory / Consultancy, Research grant / Funding (institution): Nordic; Research grant / Funding (institution): Philips; Research grant / Funding (institution): Roche. All other authors have declared no conflicts of interest.