Oncologic results and prognostic predictors of patients with locally advanced rectal cancer showing ypN0 after radical surgery following neoadjuvant chemoradiotherapy

Adjuvant chemotherapy is recommended for patients with locally advanced rectal cancer after radical surgery following neoadjuvant chemoradiotherapy (NCRT) regardless of the final pathologic stage. However, the efficacy of adjuvant chemotherapy in ypN0 patients remains controversial. The aim of this study was to evaluate the oncologic outcomes and analyze the prognostic factors for ypN0 patients in order to estimate prognosis and establish an effective adjuvant chemotherapy strategy for stage 0-II rectal cancers after radical surgery following NCRT. Between January 1999 and December 2009, the medical records of 202 patients who had been diagnosed with locally advanced rectal cancer, underwent radical surgery following NCRT, and showed ypN0 were retrospectively reviewed. The median follow-up period was 60.5 months. The 5-year local recurrence rate was 3.1 %. The 5-year disease-free survival and 5-year overall survival were 86.3 and 86.9 %. Postirradiation T3-4 and abdominoperineal resection (APR) were the independent prognostic indicators for disease-free survival (p = 0.001, p = 0.003) and overall survival (p = 0.001, p = 0.002). Adjuvant chemotherapy improved local recurrence in the patient with ypT3-4 and patients who had undergone APR (p = 0.014, p = 0.002). APR affected local recurrence, disease-free survival, and overall survival of ypT3-4 patients (p = 0.013. 0.029, and 0.001) Postirradiation T3-4 and APR are the significant prognostic factors for ypN0. Further randomized prospective study is needed to evaluate the oncologic benefit of adjuvant chemotherapy in ypN0 patients, especially those with ypT3-4 and those having undergone APR, and to confirm which chemotherapeutic agent could improve the oncologic outcomes of patients poorly responding to NCRT.