Perineural invasion as both a prognostic factor for stage II rectal cancer and an indicator for adjuvant chemotherapy.

Perineural invasion (PNI) is widely recognized as a significant indicator of tumor aggressiveness and poor prognosis. In patients with stage II colorectal cancer, the presence of PNI may suggest a higher risk of disease recurrence. Therefore, evaluating the potential benefits of adjuvant chemotherapy in this high-risk subgroup is of considerable clinical relevance. Nonetheless, the therapeutic efficacy of such treatment remains a matter of ongoing debate. A retrospective study was conducted on data from patients with stage II rectal cancer (RC) obtained from the Surveillance, Epidemiology, and End Results database (2013-2014) of the National Cancer Institute. Kaplan-Meier survival analysis was performed to estimate survival rates, and group comparisons were conducted using the log-rank test. Univariate and multivariate Cox proportional hazards regression analyses were employed to assess the associations between clinicopathological factors and both overall survival (OS) and cancer-specific survival (CSS). Among the 1372 patients included in the analysis, 144 (10.5%) exhibited PNI. The presence of PNI was significantly associated with carcinoembryonic antigen levels, T stage, and receipt of chemotherapy. Cox proportional hazards regression analysis identified age, carcinoembryonic antigen levels, PNI, radiotherapy, chemotherapy, T stage, and the number of regional lymph nodes examined as independent prognostic factors for both OS and CSS. Additionally, postoperative chemotherapy was associated with improved OS and CSS in patients with stage II RC. PNI is a poor prognostic factor for stage II RC patients. Postoperative chemotherapy improved the prognosis of stage II RC patients with PNI(+).