Induction chemotherapy followed by chemoradiotherapy and TME for high-risk locally advanced rectal cancer.

Abstract

e14059 Background: Induction chemotherapy (ICT) followed by chemoradiation (CRT) may improve tumor downsizing and disease control among patients (pts) with locally advanced rectal cancer (LARC). We retrospectively assessed the safety and short-term efficacy of ICT followed by CRT and total mesorectal excision (TME) in pts with high-risk LARC with or without resectable metastases. Methods: We reviewed records of 34 consecutive stage III (n=15) or stage IV (n=19) pts with locally advanced rectal tumors treated with ICT followed by CRT between 12/06-1/10. Pts had high-risk primary tumors based on advanced T and/or N stage by endorectal ultrasound and/or MRI: T3 (n= 28), T4 (n=6) and N1 (N=9), N2 (n=19). Recurrence-free (RFS) and overall survival (OS) were estimated by Kaplan-Meier method. Results: Median age was 52 yrs, 65% were female. Pts received a median of 6 cycles of 5-FU based ICT combined with oxaliplatin (n=29), irinotecan (n=2), or both (n=3). CRT (median dose 50.4 Gy) was delivered with continuous infusion 5-FU; one pt did not complete the prescribed CRT. During ICT, 9 (27%) pts experienced grade 3+ heme toxicity. Grade 3+ heme or GI toxicity occurred in 3 (9%) and 2 (6%) pts, respectively during CRT. 7 pts did not undergo surgery due to: progression of disease (n=2); comorbid disease (n=2); or pt refusal (n=3). 27 pts proceeded to TME including 14 with clinical distant metastasis, 11 of whom underwent metastasectomy; 3 additional pts no longer had clinically identifiable liver (n=2) or sacral (n=1) lesions. All 27 pts had complete rectal resection, one had a circumferential margin < 1 mm. 17 pts had tumor response > 90% including 9 with pathologic CR. 2 pts had pathologic CR in resected metastasis. Post-op complications included: pelvic abscess (n=1) and pulmonary atelectasis (n=1). With a median follow-up of 25 mos, none of the 27 pts who underwent rectal resection developed local recurrence. The 3 yr RFS and OS among resected stage III pts was 63% and 100%, respectively; 3-yr OS for resected stage IV pts was 82%. Conclusions: ICT prior to CRT is associated with acceptable toxicity, substantial tumor regression, and promising clinical outcomes in pts with high-risk LARC, including pts with resectable metastatic disease.