Prognostic significance of performing universal HER2 testing in cases of advanced gastric cancer.

Jiménez-Fonseca P1, Carmona-Bayonas A2, Sánchez Lorenzo ML3, Plazas JG4, Custodio A5, Hernández R6, Garrido M7, García T2, Echavarría I8, Cano JM9, Rodríguez Palomo A10, Mangas M11, Macías Declara I12, Ramchandani A13, Visa L14, Viudez A15, Buxó E16, Díaz-Serrano A17, López C18, Azkarate A19, Longo F20, Castañón E21, Sánchez Bayona R21, Pimentel P22, Limón ML23, Cerdá P24, Álvarez Llosa R25, Serrano R26, Lobera MP27, Alsina M28,Hurtado Nuño A29, Gómez-Martin C17.

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Abstract

BACKGROUND:

Trastuzumab significantly improves overall survival (OS) when added to cisplatin and fluoropyrimidine as a treatment for HER2-positive advanced gastric cancers (AGC). The aim of this study was to evaluate the impact of the gradual implementation of HER2 testing on patient prognosis in a national registry of AGC.

METHODS:

This Spanish National Cancer Registry includes cases who were consecutively recruited at 28 centers from January 2008 to January 2016. The effect of missing HER2 status was assessed using stratified Cox proportional hazards (PH) regression.

RESULTS:

The rate of HER2 testing increased steadily over time, from 58.3 % in 2008 to 92.9 % in 2016. HER2 was positive in 194 tumors (21.3 %). In the stratified Cox PH regression, each 1 % increase in patients who were not tested for HER2 at the institutions was associated with an approximately 0.3 % increase in the risk of death: hazard ratio, 1.0035 (CI 95 %, 1.001-1.005), P = 0.0019. Median OS was significantly lower at institutions with the highest proportions of patients who were not tested for HER2.

CONCLUSION:

Patients treated at centers that took longer to implement HER2 testing exhibited worse clinical outcomes. The speed of implementation behaves as a quality-of-care indicator. Reviewed guidelines on HER2 testing should be used to achieve this goal in a timely manner.