Preoperative chemoradiotherapy (QT-RT) with capecitabine and oxaliplatin (CAPOX) or capecitabine alone (CAP) in patients (PTS) with locally advanced rectal cancer (LARC).

Abstract

e14712 Background: Preoperative concomitant QT-RT has shown to improve sphincter preservation and local control in LARC. We analyzed two cohorts of pts diagnosed of LARC treated with QT-RT with CAP or CAPOX. Methods: Pts with LARC (T3-T4 and/or N+) were treated with pelvic radiotherapy (45Gy in 25 fractions) concomitant with oxaliplatin (50mg/m2 day 1, 8, 22 and 29) and capecitabine (1650mg/m2 on days 1 to 14 and 22 to 35) or CAP (825mg/m2 bid for 5 days/week). Surgery was scheduled 6 weeks after completion QT-RT. Main end points assessed were: toxicity of preoperative chemotherapy, rate of sphincter preservation, pathological complete response (pCR) rate, and progression-free survival (PFS). Results: From Aug 2002 to Nov 2012, 254 pts with LARC were included; 53 pts received preoperative chemotherapy with CAP (cohort A) and 201 pts with CAPOX (cohort B). Median age: 65. Pts characteristics in cohort A: ECOG 0/1/2: 13/35/5; upper/mid/distal rectum 5/25/23; stage II/III 10/43. Pts characteristics in cohort B: ECOG 0/1/2: 48/149/4; upper/mid/distal rectum 29/105/67; stage II/III 27/174. 51 pts in cohort A (96.2%) and 192 (95%) in cohort B received full dose of preoperative QT-RT. Main toxicities in cohort A were diarrhea grade 2/3: 2/3 and neutropenia grade 2/3: 1/0; in cohort B were diarrhea grade 2/3: 42/24, neutropenia grade 2/3: 2/1 and neurotoxicity grade 1/2: 94/7. Surgery: 53 pts (100%) in cohort A and 198 pts (98.5%) in cohort B. Sphincter preservation and R0 resections were achieved in 58% pts and 98% pts respectively in cohort A, and 62% pts and 91.5% pts in cohort B. pCR was achieved in 11% pts in cohort A and 17% pts in cohort B. 3-year PFS and overall survival were 62% and 82% respectively in cohort A, and 75% and 83% in cohort B. Adding oxaliplatin in pts cT4/N- or N+ does not improve PFS (p=0.73). Downstaging in cohort A and B was achieved in 69.8% pts and 65% pts respectively. Conclusions: Combination QT-RT based in CAP or CAPOX is a well tolerated regimen and achieved encouring rates of pCR, R0 resection, sphincter preservation and tumor downstaging without differences in PFS in high risk pts with LARC.