Different Doses And Type Of Radiation In Neoadjuvant Chemoradiation In Rectal Cancer

PurposeTo evaluate the rate of pathologic response and acute toxicity of neoadjuvant chemoradiation for advanced T3/T4distal rectal cancers according to the different doses delivered to the pelvic cavity and the type of radiation technique.Patients and MethodsWe retrospectively studied50patients with T3-4rectal cancer recruited from2006until2011in Sir Run Run Shaw Hospital of Zhejiang University. Preoperative pelvic radiotherapy was performed with5fractions per week,21patients received a total dose of40-45Gy,18patients received a total dose of50Gy, another11patients got IMRT with a dose of47-48Gy.All50patients simultaneous received5-FU-basedchemotherapy during the period of radiotherapy. Surgery was performed6to8weeks after completion of neoadjuvant therapy. The evaluation scale of this study are acute chemoradiation toxicity, pathologic response rate, TRG(tumor regression grading) by Dworak, CEA changes as well as prognosis.ResultsAcute grade3-4toxicity rate was different in arml and arm2(16.7%vs50%, p=0.016).Tumor MRI downstaging, pathologic downstaging,TRG, local recurrence rate observed in three arms are almost the same.ConclusionHigher dose of radiation (a total pelvic dose of50Gy) in preoperative chemoradiotherapy despite a moderate increase in acute toxicity has no impact on pathologic downstaging and prognosis. Lower doseage of radiation or IMRT is recommended for T3-4rectal cancer patients.