A Population-Based Cohort Study of Venous Thromboembolism Rates Following Surgery and During Adjuvant Chemotherapy in Patients With Colon Cancer.

BACKGROUND: There is an elevated risk of venous thromboembolism in patients treated for colon cancer. Postoperative venous thromboembolism has been studied previously, but no large study has compared the risks during different stages of treatment. OBJECTIVE: This study aimed to quantify and compare the risks of venous thromboembolism before surgery, after surgery, during adjuvant chemotherapy, and up to 365 days after surgery among patients with resected colon cancer. DESIGN: This is a population-based retrospective cohort study. SETTING: This study was conducted in a single-payer, universal health care setting (Ontario) between 2002 and 2008. PATIENTS: A total of 6806 patients with stage I to III colon cancer treated with surgical resection were included. INTERVENTIONS: Phases of treatment were evaluated, including preoperative, in-hospital, postoperative, during adjuvant chemotherapy, and 365 days postoperatively. MAIN OUTCOME MEASURES: Venous thromboembolism, as defined using diagnostic codes from administrative data sources, was the primary outcome measured. RESULTS: Of the 6806 patients included, 327 (5%) developed venous thromboembolism. Patients receiving adjuvant chemotherapy had a higher risk versus surgery-alone patients (6% vs 4%, p < 0.001). Of the 327 who developed venous thromboembolism, 32% (1.6% overall) were diagnosed during hospital admission and 13.5% (0.6% overall) were diagnosed between discharge and 30 days after surgery. The majority of venous thromboembolisms diagnosed in patients receiving adjuvant chemotherapy (53%, 3.1% of all patients receiving adjuvant chemotherapy) were diagnosed within 180 days of starting adjuvant chemotherapy. Venous thromboembolism was an independent risk factor for worse 5-year overall survival (HR, 1.65; 95% CI, 1.43-1.91; p < 0.001). LIMITATIONS: This study was limited by the potential for misclassification of venous thromboembolism and unknown compliance with prophylaxis recommendations. CONCLUSION: Patients who undergo treatment for stage I to III colon cancer are at considerable risk of developing venous thromboembolism. The risk is elevated in those who require adjuvant chemotherapy, and venous thromboembolism is associated with worse long-term outcomes. There may be a role of venous thromboembolism prophylaxis during all phases of treatment, including both after surgery and during adjuvant chemotherapy. See Video Abstract at http://links.lww.com/DCR/B123. UN ESTUDIO DE COHORTE POBLACIONAL DE LAS TASAS DE TROMBOEMBOLISMO VENOSO DESPUÉS DE CIRUGÍA Y DURANTE QUIMIOTERAPIA ADYUVANTE EN PACIENTES CON CÁNCER DE COLON: Existe un riesgo elevado de tromboembolismo venoso en pacientes tratados por cáncer de colon. El tromboembolismo venoso postoperatorio se ha estudiado previamente, pero ningún estudio grande ha comparado los riesgos durante las diferentes etapas del tratamiento.Cuantificar y comparar los riesgos de tromboembolismo venoso antes de la cirugía, después de la cirugía, durante quimioterapia adyuvante y hasta 365 días después de cirugía en pacientes con cáncer de colon resecado.Estudio retrospectivo de cohorte poblacional.Escenario de atención médica universal con pagador único (Ontario) entre 2002-2008.6,806 pacientes con cáncer de colon en estadio I-III tratados con resección quirúrgica.Fase de tratamiento, incluyendo preoperatorio, hospitalización, postoperatorio, durante quimioterapia adyuvante y 365 días después de la operación.Tromboembolismo venoso, tal como se define utilizando códigos de diagnóstico de fuentes de datos administrativos.Se incluyeron 6,806 pacientes, con 327 (5%) que desarrollaron tromboembolismo venoso. Los pacientes que recibieron quimioterapia adyuvante tuvieron un mayor riesgo en comparación con los pacientes con cirugía solamente (6% vs 4%, p <0.001). De los 327 que desarrollaron tromboembolismo venoso, 32% (1.6% en general) fueron diagnosticados durante el ingreso hospitalario y 13.5% (0.6% en general) fueron diagnosticados entre el alta y 30 días después de la cirugía. La mayoría de los tromboembolismos venosos diagnosticados en pacientes que recibieron quimioterapia adyuvante (53%, 3.1% de todos los pacientes con quimioterapia adyuvante) fueron diagnosticados dentro de los 180 días de comenzar la quimioterapia adyuvante. El tromboembolismo venoso fue un factor de riesgo independiente para una peor supervivencia general a 5 años (Hazard Ratio (cociente de riesgo) 1.65, IC 95% 1.43-1.91, p <0.001).Potencial de clasificación errónea del tromboembolismo venoso, cumplimiento desconocido de las recomendaciones de profilaxis.Los pacientes que se someten a tratamiento para el cáncer de colon en estadio I-III tienen un riesgo considerable de desarrollar tromboembolismo venoso. El riesgo es elevado en aquellos que requieren quimioterapia adyuvante y el tromboembolismo venoso se asocia con peores resultados a largo plazo. La profilaxis del tromboembolismo venoso puede desempeñar un papel durante todas las fases del tratamiento, incluyendo tanto el periodo posquirúrgico como durante la quimioterapia adyuvante. Consulte Video Resumen en http://links.lww.com/DCR/B123.