Preoperative fluorouracil (FU)-based chemoradiation with and without weekly oxaliplatin in locally advanced rectal cancer: Pathologic response analysis of the Studio Terapia Adiuvante Retto (STAR)-01 randomized phase III trial

Abstract

CRA4008 Background: Oxaliplatin (OXA) enhances the efficacy of FU-based chemotherapy in colon cancer. This randomized phase III trial investigated the effect of adding OXA to preoperative (preop) FU-based pelvic chemoradiation (CRT) in patients (pts) with locally-advanced rectal cancer. Methods: Eligibility required a resectable, biopsy-proven rectal adenocarcinoma within 12 cm from the anal verge with radiological evidence of perirectal fat or lymphnode involvement. Randomization was between infused FU (225 mg/msq/day) concomitant to external-beam pelvic radiation (50.4 Gy in 28 daily fractions) (arm A) or the same regimen + weekly OXA (60 mg/msq × 6) (Arm B). Surgery was scheduled 6–8 weeks after completing CRT. Overall survival was the primary endpoint. A protocol-planned analysis of local tumor response to preop treatment (secondary end-point) is the object of this report. Results: 747 pts from 41 Italian centers were randomized between 12/2003 and 8/2008 (arm A/B: 379/368). Pretreatment characteristics in arm A/B: median age 63/62 years; male:female 2:1; median distance from anal verge 6 cm; T4 16/14%, N+ 63/65%. Overall grade 3–4 toxicity rates on treated pts (mainly diarrhoea) were 8% and 24% (arm A/B, p<0.001). 96/90% of pts (arm A/B) received > 90% of the planned RT. 82% of Arm B pts had > 5 oxa courses. 358/342 pts (arm A/B) had surgery at a median of 52/53 days from the end of CRT, 14 pts in each arm were not operated (progression 8, death 5, other/unknown 15) and surgery data are not yet available for 19 pts. Pathologic response data analyzed on the randomized population are reported in the table . Conclusions: The addition of weekly OXA to standard FU-based preop CRT significantly increases toxicity without affecting local tumor response. The reduced pathologic M+ rate suggests a potential effect on distant micrometastases. Longer follow-up is needed to assess the impact on efficacy endpoints. [Table: see text] No significant financial relationships to disclose.