Can radiotherapy improve the long-term survival of rectal cancer patients with perineural invasion?

Abstract

Abstract Background: Perineural invasion (PNI) is one of the aggressive characteristics of rectal cancer (RC), but there have been none studies evaluating the clinical efficacy of radiotherapy (RT) on rectal cancer with PNI. Methods: Data on RC patients staged at II/III were extracted from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2014 to verify the clinical significance of PNI. The primary outcome wre overall survival (OS) and cancer specific survival (CSS). A nomogram was established to predict the prognosis of PNI patients using SEER database and validated by Fujian Cancer Hospital. Kaplan-Meier curve was conducted to investigate the overall survival (OS) between groups. Results: 1596 patients receiving direct surgery and adjuvant chemotherapy were eligible for this study, including 288 patients (18.0%) were present with PNI. PNI was found to be independently associated with OS and CSS after adjusting for age, sex, stage, pathological factors, and treatment factors (all p < 0.05). A nomogram was established to predict the prognosis of PNI patients with high C-index, and then validated by 98 patients from FJCH. And then patients in the high-risk subgroup were found to be benefited from adjuvant RT according to the current nomogram (P<0.05), but not those in the low-risk subgroup (P>0.05). Conclusions: PNI was confirmed to be an independnet prognosis factor of RC patients, and it should also taken into consideration of the postoperative management of RC.