Relation between outcomes and response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

The objective of this study was to clarify the therapeutic effectiveness of neoadjuvant chemoradiotherapy (NCRT) with S-1 and irinotecan, we studied histopathological results and outcomes in a phase I/II study in patients with locally advanced rectal cancer treated at our hospital. We studied 76 patients enrolled in a phase I/II study of NCRT with S-1 (80 mg/m2) and irinotecan (80 mg/m2). The median follow-up was 4.6 years, and 20 patients (26.3%) had recurrence. The rate of recurrence according to tumor grade was 61.9% (13.21) in grade I, 24.0% (6/25) in grade II, and 3.3% (1/30) in grade III. Other types of cancer (outside of the radiation field) developed in 2 patients. Nine patients (11.8%) died, including 6 deaths (7.9%) from rectal cancer. In grade III disease, only 1 patient with systemic metastases had recurrence. Among patients with grade I disease, a high proportion had distant metastases, irrespective of clinical characteristics. Our results suggest that treatment response to NCRT is related to outcomes in patients with locally advanced rectal cancer. Future clinical trials of NRCT in advanced lower rectal cancer should assess the relation between treatment response and outcomes. Ways to predict treatment response on the basis of biopsy specimens obtained before therapy should also be investigated. (author)