T. Suzuki1, K. Suwa1, K. Hanyu1, Y. Mitsuyama1, K. Eto1, M. Ogawa1, T. Okamoto1, T. Fujita1, M. Ikegami2, K. Yanaga1 1The Jikei University School Of Medicine,Department Of Surgery,Tokyo, , Japan 2The Jikei University School Of Medicine,Department Of Pathology,Tokyo, , Japan
Introduction: Perineural invasion (PNI) is associated with decreased survival in several malignancies, but no robust evidence has been documented in colorectal cancer (CRC). The aim of the present study was to evaluate the association of PNI and outcomes of patients after colorectal resection for CRC, focusing on the impact of adjuvant chemotherapy on survival rates of patients with PNI.
Methods: We retrospectively reviewed 224 consecutive patients who underwent surgery for Stage I to IV CRC between January 1999 and December 2004. The presence or absence of PNI of the tumor was determined by experienced pathologists in our institution. Overall and disease-free survival rates were estimated using the Kaplan-Meier method, and intergroup differences in survival curves were tested with the log-rank test. To evaluate the correlation between PNI and survival, PNI was entered into a Cox proportional hazards model as an independent variable.
Results: PNI was detected in 63 of the 224 patients (28%) and positively correlated with lymphatic invasion (P = 0.003), venous invasion (P = 0.006), lymph node involvement (P = 0.002), size of tumor (P = 0.019), postoperative chemotherapy (P = 0.023), and incidence of metastasis or recurrence (P < 0.0001). The 5-year disease-free survival rate was 1.6-fold in patients with PNI-negative tumors as compared to PNI-positive tumors (66% vs 44%, respectively; P < 0.001). The 5-year overall survival rate was 71% for PNI-negative tumors, which was significantly higher than 40% for PNI-positive tumors (P < 0.001). A multiple regression analysis revealed that PNI was a strong prognostic factor for overall survival. In a subset analysis of patients with stage III CRC, adverse effects of PNI on survival were attenuated by adjuvant chemotherapy, but adjuvant chemotherapy did not completely reverse the effects of PNI.
Conclusion:PNI was associated with poor prognostic markers such as lymphatic invasion and lymph node involvement, and predicted worse survival in patients with stage III CRC. Adverse effects of PNI on survival were attenuated by adjuvant chemotherapy. Intensive chemotherapy and strict surveillance seem be warranted in patients with CRC of stage III with PNI.