Objective: To validate the associations previously found in three cohorts of patients from the General University Hospital Gregorio Marañón, between the polymorphisms rs1128503, rs2032582 and rs1045642 of the ABCB1 gene and the hand-foot syndrome and diarrhea in colorectal cancer patients treated with chemotherapy regimes containing Capecitabine and 5-Fluorouracil, respectively, and between the polymorphisms rs2297595 of the DPYD gene and nausea/vomiting, rs11615 of ERCC1 and neutropenia, and rs28399433 CYP2A6 and neutropenia, in colorectal cancer patients treated with FOLFOX or XELOX as adjuvant therapy.
Method: Colorectal cancer patients treated with chemotherapy regimes, containing Capecitabine (n = 157), 5-Fluorouracil (n = 99) were included in the study, as well as patients treated with XELOX or FOLFOX (n = 83) as adjuvant therapy. The patients included were recruited from the Doce de Octubre University Hospital and from the Gregorio Marañón General University Hospital, and signed the informed consent form. DNA was obtained from blood samples. Genotyping was carried out with SNaPshot. Contingency tables were created for analyzing the associations between the genotypes and the adverse reactions.
Results: None of the associations previously identified was replicated in the validation cohort.
Conclusions: Pharmacogenetic studies with a limited sample size must be validated with bigger cohorts, if possible by means of multicentre studies, reducing the variables to the maximum and should never be used in clinical practice without validation.
Objetivo: Validar las asociaciones, encontradas previamente en tres cohortes de pacientes del Hospital General Universitario Gregorio Marañón, entre los polimorfismos rs1128503, rs2032582 y rs1045642 del gen ABCB1 con síndrome manopie y diarrea en pacientes de cáncer colorrectal tratados con regímenes que contenían capecitabina y 5-Fluorouracilo, respectivamente, y entre los polimorfismos rs2297595 del gen DPYD con nauseas/vómitos, rs11615 ERCC1 y neutropenia, y rs28399433 CYP2A6 y neutropenia en pacientes de cáncer colorrectal tratados con FOLFOX o XELOX en adyuvancia. MÉTODO: Se incorporaron al estudio pacientes de cáncer colorrectal tratados con regímenes quimioterápicos que contenían capecitabina (n = 157), 5-fluorouracilo (n = 99) y pacientes tratados en adyuvancia con XELOX o FOLFOX (n = 83). Los pacientes participantes fueron reclutados en el Hospital Universitario Doce de Octubre y en el Hospital General Universitario Gregorio Marañón tras firmar consentimiento informado. Se extrajo ADN a partir de muestras de sangre. Los genotipados se realizaron mediante SNaPshot. Se realizaron tablas de contingencia para analizar las asociaciones entre genotipos y reacciones adversas.
Resultados: Ninguna de las asociaciones previamente identificadas fue replicada en la cohorte de validación.
Conclusiones: Los estudios farmacogenéticos con un tamaño muestral limitado deben ser validados en cohortes más numerosas, a ser posible en estudios multicéntricos, reduciendo al máximo las variables y nunca deben ser utilizados en clínica sin validar.
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