Clinical Implication of Perineural and Lymphovascular Invasion in Rectal Cancer Patients Who Underwent Surgery After Preoperative Chemoradiotherapy

Abstract

BACKGROUND: Lymphovascular and perineural invasion are well-known negative prognostic indicators in rectal cancer, but previous studies on their significance are not consistent.

OBJECTIVE: This study assessed the prognostic value of lymphovascular and perineural invasion in rectal cancer patients who received preoperative chemoradiotherapy followed by curative resection.

DESIGN: This is a retrospective analysis.

SETTING: This study was performed at a tertiary cancer center.

PATIENTS: Rectal cancer patients who underwent curative resection after preoperative chemoradiotherapy between January 2000 and December 2010.

MAIN OUTCOME MEASURES: The primary outcomes were disease-free survival and overall survival. The survival rates were estimated using Kaplan-Meier analysis, and group comparisons were conducted using a log-rank test.

RESULTS: Of the 1156 included patients, 109 (9.4%) presented with lymphovascular invasion and 137 (11.9%) presented with perineural invasion. Lymphovascular and perineural invasion were associated with T and N downstaging after preoperative chemoradiotherapy (p < 0.001). In the ypN0 patients, the 5-year disease-free survival rates were 70.8% and 78.5% (p = 0.150) for the lymphovascular invasion and absent groups, respectively. In the perineural invasion group, the 5-year disease-free survival rate was 59.0% compared to 80.2% in the absent group (p = 0.001). Among the ypN+ patients, the 5-year disease-free survival rates were 36.9% and 44.4% for the lymphovascular invasion and absent groups, respectively (p = 0.211). The perineural invasion group had a poorer 5-year disease-free survival rate compared to the absent group (29.7% vs 46.7%; p = 0.011). By multivariable analyses, perineural invasion correlated with a poor disease-free survival (HR 1.412, 95% CI 1.082–1.843; p = 0.011) and also in ypN0 subgroup analysis (HR 1.717, 95% CI 1.093-2.697; p = 0.019).

LIMITATIONS: This study was a retrospective study conducted at a single center.

CONCLUSIONS: Perineural invasion is a reliable independent predictor of recurrence in rectal cancer patients treated with preoperative chemoradiotherapy. Patients with perineural invasion should be considered for closer surveillance even with ypN0 status.