Tumour-Associated Neutrophils in Colorectal Cancer: a Systematic Review, Meta-analysis, and Comprehensive Literature...

Area of Science:

• Immunology
• Oncology
• Pathology

Background:

• Neutrophils are key innate immune cells.
• The role of tumour-associated neutrophils (TANs) in cancer prognosis is not fully understood.
• Colorectal cancer (CRC) prognosis requires further clarification of immune cell involvement.

Purpose of the Study:

• To systematically evaluate the prognostic significance of TANs in colorectal cancer (CRC).
• To determine if TAN location (tumour core vs. invasive margin) influences CRC patient outcomes.

Main Methods:

• A systematic review and meta-analysis of studies published until April 2024.
• Included studies analyzed TANs via hematoxylin-eosin (HE) or immunohistochemistry (IHC) in stages I-IV CRC.
• Extracted hazard ratios for overall survival (OS) and disease-free survival (DFS) based on TAN levels at the tumour core (TC) and invasive margin (IM).

Main Results:

• 18 studies comprising 7,406 patients were analyzed.
• High TANs at the invasive margin (IM) were significantly associated with improved OS (HR=0.64) and DFS (HR=0.47).
• High TANs in the tumour core (TC) showed a non-significant trend towards better OS and DFS, with high heterogeneity.

Conclusions:

• Elevated TANs at the invasive margin (IM) indicate a favorable prognosis in colorectal cancer.
• TANs within the tumour core (TC) do not appear to have a statistically significant prognostic value in CRC.
• The location of TANs is a critical factor in their prognostic impact on colorectal cancer outcomes.