Neoadjuvant chemoradiotherapy for locally advanced rectal cancer: Predicting long-term outcomes based on response to treatment.

Abstract

621 Background: Neoadjuvant long course chemoradiotherapy is well recognised as a standard treatment in locally advanced, margin threatening rectal cancer, in order to downstage and reduce local recurrence. We investigated retrospectively whether long term outcomes could be predicted by response to neoadjuvant treatment, and which factors specifically seemed to predict a risk of poorer outcome. Methods: All patients treated with long course chemoradiotherapy between January 2008 and December 2009 were identified retrospectively. Patients were excluded if the treatment indication was for inoperable disease, postoperative, recurrence, or palliative intent. A total of 231 patients were analysed with retrospective analysis of all electronic records and case notes. The following information was collated: preoperative staging, chemoradiotherapy treatment planned and received, operation performed, postoperative pathology (including nodal status, margins, presence of LVSI, and evidence of response to neoadjuvant treatment), disease free survival, and overall survival. Results: Kaplan Meier curves are presented showing patients with either a complete or partial response to neoadjuvant treatment appear to have a statistically significant improvement in long term outcomes, compared to those with no response (Mean survival 55 months, 56 months and 43months respectively, p<0.01). Furthermore, those who remain node positive or have evidence of LVSI following neoadjuvant treatment appear to have a statistically significant poorer outcome. Conclusions: Our study further develops on previous work looking at the prediction of outcomes following response to neoadjuvant treatment in rectal cancer. It appears that those who respond to initial treatment will have a better outcome than those who do not, including those who remain node positive or with LVSI following treatment. This study is limited because it is retrospective. Randomised controlled trial data is required to enable identification of poor risk imaging and pathology features that might suggest the need for adjuvant therapy following combined modality treatment with neoadjuvant chemoradiotherapy and surgery.