# The prognostic and predictive significance of perineural invasion in stage I to III colon cancer: a propensity score matching-based analysis

## TL;DR

This study finds that perineural invasion is a poor prognostic factor in stage III colon cancer but does not predict outcomes in node-negative cases, suggesting caution in using chemotherapy for the latter.

## Contribution

The study uses propensity score matching to clarify PNI's role as a prognostic and predictive factor in stage I-III colon cancer.

## Key findings

- PNI is associated with lower 5-year overall survival in stage III colon cancer.
- PNI does not predict outcomes in node-negative colon cancer.
- Adjuvant chemotherapy benefits PNI+ node-positive but not node-negative patients.

## Abstract

Colorectal cancer (CRC) presents with varying prognoses, and identifying factors for predicting metastasis and outcomes is crucial. Perineural invasion (PNI) is a debated prognostic factor for CRC, particularly in stage I-III patients, but its role in guiding adjuvant chemotherapy for node-positive colon cancer remains uncertain.

We conducted a single-center study using data from the Colorectal Section Tumor Registry Database at Chang Gung Memorial Hospital, Taiwan. This prospective study involved 3,327 CRC patients, 1,536 of whom were eligible after application of the exclusion criteria, to investigate the prognostic value of PNI in stage I-III patients and its predictive value for node-positive/negative cancer patients receiving adjuvant chemotherapy. Propensity score matching (PSM) was used to minimize selection bias, and follow-up was performed with standardized procedures.

PNI-positive (PNI+) tumors were associated with higher preoperative CEA levels and more frequent adjuvant chemotherapy. After PSM, PNI + tumors were associated with marginally significantly lower 5-year disease-free survival (DFS) and significantly lower overall survival (OS) rates in stages III CRC. However, no significant differences were observed in stages I and II. Subgroup analysis showed that among PNI + tumors, only poorly differentiated tumors had higher odds of recurrence. PNI did not predict outcomes in node-negative colon cancer. Adjuvant chemotherapy benefited PNI + patients with node-positive but not those with node-negative disease.

Our study indicates that PNI is an independent poor prognostic factor in stage III colon cancer but does not predict outcomes in node-negative disease. Given the potential adverse effects of adjuvant chemotherapy, our findings discourage its use in node-negative colon cancer when PNI is present.

The online version contains supplementary material available at 10.1186/s12957-024-03405-6.