Investigation of the effect of perineural invasion on survival rates in rectal tumors

Abstract

Purpose: Colorectal cancers compose the third most common cancer group leading to death, with increasing rates in developed countries after lung and breast cancers. Rectal cancers make up about 30% of all colorectal cancers. Although many factors affecting recurrence and survival in rectal cancer have been identified, the stage of the tumor is the most important prognostic factor. However, many additional parameters that can be associated with survival and affect the adjuvant treatment plan have been identified besides the stage. Perineural invasion (PNI) is one of the parameters that can be associated with survival and affect the adjuvant treatment plan in colorectal cancers. The aim of this study is to investigate the effects of various histopathological prognostic factors, including PNI on disease-free survival, overall survival, and recurrence rates in the study group. Materials and methods: The clinical records of patients diagnosed with rectal cancer and operated on at the Department of General Surgery, Faculty of Medicine, Pamukkale University between 2008-2014 were reviewed. To investigate the factors affecting disease-free survival, recurrence rates, and overall survival, the presence of PNI, serum CEA levels, cTNM stage, pT stage, pN stage, number of metastatic LNs, tumor budding status, histopathological grades, lymphocyte infiltration, and presence of desmoplasia were evaluated in patients. Results: A total of 124 patients were included in the study. 42 patients (33.9%) had PNI while 82 patients (66.1%) did not. Of the 45 patients with recurrence, 26 had PNI while 19 did not have PNI. Of the 79 patients without recurrence, 16 had PNI while 63 did not exhibit any evidence of PNI. Similarly, PNI was seen more frequently in deaths related to the disease. The 3-year average survival of patients with and without PNI was 55% and 89%, respectively (p<0.05). The 5-year survival was 38% and 83% respectively (p<0.05). Similarly, there was a significant relationship between the presence of PNI and 3-year disease-free survival (46.8% and 84.1% respectively, p<0.05) and 5-year disease-free survival (22.3% and 80.4% respectively, p<0.05). In the multivariate analysis in which other prognostic factors were also evaluated, the presence of PNI was found to be significantly associated with both overall survival (HR:3.4, 95% CI:1.7-7.2) and disease-free survival (HR:3.0, 95% CI:1.6-5.6). Conclusion: PNI presence is a strong and independent prognostic indicator for survival. Large-scale, randomized, prospective studies are needed to determine whether PNI presence should be taken into account in the staging of colorectal cancer or play a role in choosing adjuvant therapy.