Comparison of two regimes of neoadjuvant chemoradiation in the treatment of rectal tumors: Bolus versus infusional fluorouracil.

Abstract

e14130 Background: In metastatic rectal cancer, continuous infusion of fluorouracil (cFU) is more effective and less toxic than the bolus regimen. However, the ideal regimen of FU administration concomitant with radiotherapy (RDT) is not well established. There are few direct comparisons of cFU versus bolus FU in the neoadjuvant setting. Methods: We conducted a retrospective analysis of 78 patients with rectal cancer, treated from August/2002 to November/2008, with external beam pelvic radiation (50.4 Gy) concomitant with the following chemotherapeutic regimens: weekly bolus FU 350-425 mg/m2 or 350-380 mg/m2 D1-D5 in the 1º and 5° weeks (group I); or cFU 1 g/m2 D1-D5 during 1º and 5° week (group II). Relapse-free survival (RFS) was the primary endpoint. Pathological response rate was secondary endpoint. Results: Data from 78 patients were analyzed (I/II:55/23). Pretreatment characteristics were: 52% female; median age 55y/52y (I/II); clinical staging approach was: CT scan in 66/56% (I/II), and magnetic resonance in 34/52% (I/II). Clinical T3-T4 69/69% and cN+ 36/43% (I/II). Groups were well balanced. The median interval from RDT to surgery was 1.84 month. Sphincter-sparing surgery was performed in 75/86% (I/II).The proposed RDT was delivered in 94/100% (I/II) of patients and median total delivered FU dose was 2.1 g/10 g (I/II). Patients in group I also received leucovorin 20 mg/m2 in 90.4%. Pathologic T3-T4 was 36/31% (I/II) and pN+ 36/26% (I/II). Pathological complete response (pCR) was achieved in 28.3/9.1% (I/II). There was no significant association between pCR and regimen of treatment (p = 0.13). The median follow-up was 27.4 m, median RFS was not reached. In 2y, RFS was 73% in both groups (p = 0.59). Twenty-six patients relapsed, 1/15 (6%) (two patients were lost for follow up) among those with pCR and 25/56 (44%) (4 patients were lost for follow-up) among those with non-pCR. Conclusions: Pathologic complete response was associated with lower relapses rates in our series. There was no difference in pCR and RFS between bolus and infusional FU. Bolus FU remains a treatment option, associated with radiotherapy, in patients with locally advanced rectal carcinoma. No significant financial relationships to disclose.