Correlation and Heterogeneity of the Immune Microenvironment and Histopathological Growth Patterns in Resectable Colorectal Cancer Liver Metastases

Primary outcomes

1. OS(Overall survival)

   Time frame: OS is defined as the time from the date of the first liver metastasis resection to death due to any cause or loss to follow-up, assessed up to 100 months.

   OS was defined as the time from the date of the first liver metastasis resection to death due to any cause or loss to follow-up.

2. RFS (Recurrence-free Survival)

   Time frame: From the date of liver resection until the first occurrence of a measurable recurrence of the disease, or until death due to any cause (whichever occurs first), the assessment period can be up to 100 months.

   The definition of recurrence-free survival is the time from the liver surgery to the first imaging evidence showing disease recurrence or death due to any cause, whichever occurs first.

3. HGPs (Histopathological Growth Patterns)

   Time frame: From the completion of HE staining to the failure of staining or the damage and loss of the slides, the assessment period can be up to 100 months.

   The histopathological growth pattern of the tumor-liver interface.

4. TME (Tumor Microenvironment)

   Time frame: From the completion of mIHC staining to the failure of staining or the damage and loss of the slides, the assessment period can be up to 100 months.

   Multiplex immunohistochemistry (mIHC) staining was performed on FFPE sections of liver metastases using two panels (Panel 1: CD4, CD8A, Foxp3, PD-L1, Panck; Panel 2: CD68, CD163, FAP-α, α-SMA, Panck), encompassing a total of nine immune cell markers. Using QuPath pathology imaging software, tissue sections were divided into the tumor center (defined as regions >500 μm from the liver-tumor interface) and the invasive tumor front (defined as a 1 mm region extending 500 μm on either side of the liver-tumor interface). Quantitative analysis of immune cell populations was performed in the tumor center, the invasive tumor front, and regions corresponding to different histopathological growth patterns.