Respuesta al tratamiento e intervalo de tiempo hasta la cirugía con radioterapia preoperatoria de curso corto en el cáncer de recto / Response to treatment and interval to surgery after preoperative short-course radiotherapy in rectal cancer

INTRODUCCIÓN: La radioterapia preoperatoria de curso corto con cirugía inmediata, mejora el control local del cáncer rectal. Las respuestas que consigue son de menor magnitud que las descritas con radioquimioterapia. Datos preliminares asocian esta menor respuesta al corto periodo hasta la cirugía. El objetivo de este estudio es analizar la respuesta obtenida con el esquema preoperatorio de curso corto y su correlación con el tiempo hasta la cirugía, analizando especialmente a los pacientes con fascia mesorrectal afectada. MÉTODOS: Se analiza retrospectivamente a 155 pacientes tratados con radioterapia preoperatoria (5×5Gy). Se cuantificó la respuesta tumoral en términos de tasas de respuesta completa patológica, reducción del estadio, grado de regresión tumoral y estado del margen de resección circunferencial. RESULTADOS: El intervalo medio radioterapia-cirugía fue de 23 días. Se alcanzaron respuestas completas patológicas en el 2,2% y reducción del estadio en el 28%. No se detectaron diferencias entre estas tasas y el intervalo hasta la cirugía. Ochenta y ocho pacientes tenían resonancia de estadificación (31 con fascia mesorrectal comprometida). La media de tiempo hasta la intervención en pacientes con fascia comprometida y cirugía R0 fue de 27 días y si R1 de 16 días (p = 0,016). El punto de corte de 20 días alcanzó la mayor probabilidad de lograr un margen circunferencial negativo entre los pacientes con fascia mesorrectal comprometida, aunque sin alcanzar significación estadística: RR 3,036, IC del 95%=0,691-13,328, p = 0,06. CONCLUSIONES: Tras la radioterapia preoperatoria de curso corto, un intervalo > 20 días potencia la probabilidad de lograr un margen de resección libre en pacientes con fascia mesorrectal comprometida

INTRODUCTION: Preoperative short-course radiotherapy with immediate surgery improves local control in patients with rectal cancer. Tumor responses are smaller than those described with radiochemotherapy. Preliminary data associate this lower response to the short period until surgery. The aim of this study is to analyze the response to preoperative short-course radiotherapy and its correlation with the interval to surgery especially analyzing patients with mesorectal fascia involvement. METHODS: A total of 155 patients with locally advanced rectal cancer treated with preoperative radiotherapy (5×5Gy) were retrospectively analyzed. Tumor response in terms of rates of complete pathological response, downstaging, tumor regression grading and status of the circumferential resection margin were quantified. RESULTS: The mean interval from radiotherapy to surgery was 23 days. The rate of complete pathological response was 2.2% and 28% experienced downstaging (stage decreased). No differences between these rates and interval to surgery were detected. Eighty-eight patients had magnetic resonance imaging for staging (in 31 patients the mesorectal fascia was involved).The mean time to surgery in patients with involvement of the fascia and R0 surgery was 27 days and 16 days if R1 (P = .016). The cutoff of 20 days reached the highest probability of achieving a free circumferential resection margin between patients with mesorectal fascia involvement, with no statistically significant differences: RR 3.036 95% CI = (0.691-13.328),P = .06. CONCLUSIONS: After preoperative short-course radiotherapy, an interval>20 days enhances the likelihood of achieving a free circumferential resection margin in patients with mesorectal fascia involvement

Response to treatment and interval to surgery after preoperative short-course radiotherapy in rectal cancer. / Respuesta al tratamiento e intervalo de tiempo hasta la cirugía con radioterapia preoperatoria de curso corto en el cáncer de recto.

INTRODUCTION: Preoperative short-course radiotherapy with immediate surgery improves local control in patients with rectal cancer. Tumor responses are smaller than those described with radiochemotherapy. Preliminary data associate this lower response to the short period until surgery. The aim of this study is to analyze the response to preoperative short-course radiotherapy and its correlation with the interval to surgery especially analyzing patients with mesorectal fascia involvement. METHODS: A total of 155 patients with locally advanced rectal cancer treated with preoperative radiotherapy (5×5Gy) were retrospectively analyzed. Tumor response in terms of rates of complete pathological response, downstaging, tumor regression grading and status of the circumferential resection margin were quantified. RESULTS: The mean interval from radiotherapy to surgery was 23 days. The rate of complete pathological response was 2.2% and 28% experienced downstaging (stage decreased). No differences between these rates and interval to surgery were detected. Eighty-eight patients had magnetic resonance imaging for staging (in 31 patients the mesorectal fascia was involved).The mean time to surgery in patients with involvement of the fascia and R0 surgery was 27 days and 16 days if R1 (P=.016). The cutoff of 20 days reached the highest probability of achieving a free circumferential resection margin between patients with mesorectal fascia involvement, with no statistically significant differences: RR 3.036 95% CI=(0.691-13.328), P=.06. CONCLUSIONS: After preoperative short-course radiotherapy, an interval>20 days enhances the likelihood of achieving a free circumferential resection margin in patients with mesorectal fascia involvement.