Background: In earlier years, postoperative chemoradiotherapy was a recommended standard treatment for locally advanced rectal cancer. Based on several clinical trials, the pre-operative approach was then considered a favorable optimal time to
deliver the treatment due to significant improvement in local tumor control. Given that, both pre-operative and postoperative approaches were performed in Phramongkutklao Hospital.
Objective: This study compared 2-year disease-free survival (DFS) between pre-operative and postoperative chemoradiotherapy in locally advanced rectal cancer.
Material and Method: A retrospective study was conducted in 78 patients with clinical stage T3, T4 or node-positive disease who had received either pre-operative or postoperative concurrent chemoradiation that was carried out between 2004 and 2008. The combined multimodality approach consisted of Fluorouracil (5-FU) based chemotherapy and a long course of radiation therapy. After the last session of chemoradiotherapy in the pre-operative group, surgery was performed 4-6 weeks later followed by remaining cycles of chemotherapy whereas the postoperative group began chemoradiotherapy 4-6 weeks after surgery. The primary end point was 2-year disease-free survival (DFS).
Results: Of the eligible 78 patients, 19 patients (9 pre-operative, 10 postoperative) had recurrence during the first two years after completion of radiotherapy by which the first event of recurrence was classified as either local recurrence only, distant metastasis only, or both local and distant recurrence. The 2-year DFS between these two groups was not statistically different (78.6% pre-operative vs. 72.2% postoperative, p = 0.521), however, the pre-operative, concurrent chemoradiotherapy provided a possible DFS benefit. No statistical difference in overall toxic events between the two treatment groups; however,
there is a tendency to develop more toxicity in the postoperative group.
Conclusion: No significant statistical difference in 2-year DFS between the pre-operative and postoperative but possible DFS benefit was suggested in pre-operative group.

Keywords: Locally advanced rectal cancer, Pre-operative chemoradiotherapy, Postoperative chemoradiotherapy