Prognostic value of perineural invasion in patients with stage II colorectal cancer.

BACKGROUND: Perineural invasion (PNI) may influence the prognosis after resection of colorectal cancer (CRC); whether this is a definite prognostic factor remains controversial. This study determined the clinicopathologic factors associated with oncologic outcome after radical resection of stage II CRC, focusing on PNI.

MATERIALS AND METHODS: We retrospectively reviewed 341 consecutive patients who underwent curative surgery for stage II CRC between January 2001 and December 2006. Of these, 278 patients (81.5%) received postoperative 5-fluorouracil-based chemotherapy. The oncologic outcomes and the risk factors for recurrence were analyzed.

RESULTS: PNI was detected in 57 of 341 patients (16.7%) and was significantly associated with depth of tumor invasion (P = .035) and positive lymphovascular invasion (P < .001). Multivariate analyses revealed that PNI was a significant independent prognostic factor for disease-free survival, not for overall survival. With a median follow-up period of 57.6 months, the 5-year disease-free and overall survival rates of the patients were 80.2 and 82.6%, respectively. The 5-year disease-free survival of the PNI-negative group was significantly higher than that of the PNI-positive group (P < .001). Within the PNI-positive patients, those receiving chemotherapy had significantly higher 5-year disease-free survival than the others (P = .023).

CONCLUSION: This study illustrates the value of PNI as a prognostic factor for stage II CRC. Moreover, PNI-positive patients should be considered for postoperative chemotherapy.