Impact of neoadjuvant and adjuvant radiotherapy on disease-specific survival in patients with stages II–IV rectal cancer

OBJECTIVES: The purposes of this study were to determine whether neoadjuvant or adjuvant radiotherapy affected disease-specific survival (DSS) in patients with rectal cancer and whether stratification by tumor stage affected the results. RESULTS: 55.5% patients had neoadjuvant-radiotherapy (NRT), and 18.3% patients had adjuvant- radiotherapy (ART). Multivariable models showed that treatment type was independently associated with DSS. Patients with stages III/IV tumors who received ART plus chemotherapy had significantly worse DSS than did those who received NRT plus chemotherapy (NCRT) (P = 0.03). Among patients with stage II tumors, those who received ART plus chemotherapy and those who received NCRT had similar DSS. Further stratification by risk group revealed that patients with stage IIIA tumors who received ART plus chemotherapy had significantly better DSS than did those who received NCRT (P = 0.04). The ART plus chemotherapy and NCRT groups had similar DSS in patients with stage IIA tumors. Among high-risk patients (T3N+/T4), the NCRT group had significantly better DSS than did the ART plus chemotherapy group. Patients who underwent surgery only had the worst DSS of all the treatment groups. MATERIALS AND METHODS: From the Surveillance, Epidemiology, and End Results database, patients diagnosed with stages II–IV rectal cancer from 2004–2014 were identified. Clinicopathologic features, treatments, and DSS in different treatment groups were compared. CONCLUSIONS: NCRT or ART plus chemotherapy can reduce deaths from rectal cancer. Patients with stage IIIA tumors will benefit most from ART plus chemotherapy, whereas NCRT should be recommended to patients with stages II, IIIB, or higher tumors.