Comparative Analysis of Tertiary Lymphoid Structures for Predicting Survival of Colorectal Cancer: A Whole-Slide Images-Based Study

Life Sciences Medicine Oncology Immunology
colorectal cancer tertiary lymphoid structures digital pathology prognosis immune

Colorectal Cancer (CRC) is one of the most prevalent malignancies globally, with its prognosis closely related to immune responses within the tumor microenvironment. In recent years, Tertiary Lymphoid Structures (TLS), as an essential component of the tumor microenvironment, have been associated with favorable patient outcomes. TLS are aggregates of immune cells, including B cells and T cells, resembling Secondary Lymphoid Organs (SLO), which form in non-lymphoid tissues and play a crucial role in chronic inflammation or tumor environments. Although multiple studies have shown that the presence of TLS is associated with improved prognosis in various solid tumors, their specific role in colorectal cancer has not been fully investigated. Moreover, the definition and quantification methods for TLS have not been standardized, limiting their clinical application.

To address this gap, a research team from multiple hospitals in China conducted a multicenter study aimed at identifying a more stable method to quantify TLS and clarify its prognostic value in colorectal cancer. The study analyzed Whole-Slide Images (WSIs) from 1,609 patients, evaluating the number, maximum length, and density of TLS, and explored their relationship with patient survival rates.

Source of the Study

The research was conducted by a team from Guangdong Provincial People’s Hospital, Fudan University Shanghai Cancer Center, Chongqing Medical University, and other institutions, with key authors including Ming He, Huifen Ye, and Liu Liu. The findings were published on October 18, 2024, in the journal Precision Clinical Medicine, under the title Comparative Analysis of Tertiary Lymphoid Structures for Predicting Survival of Colorectal Cancer: A Whole-Slide Images-Based Study.

Research Process

1. Study Subjects and Data Collection

The study enrolled 1,609 colorectal cancer patients from four hospitals, divided into three cohorts: a primary cohort (545 patients), a validation cohort (888 patients), and a The Cancer Genome Atlas (TCGA) cohort (176 patients). Clinical data for all patients included age, sex, tumor location, Carcinoembryonic Antigen (CEA) levels, tumor grade, TNM stage, and Microsatellite Instability (MSI) status.

2. Quantification Methods for TLS

The research team quantified TLS using Hematoxylin and Eosin (H&E)-stained Whole-Slide Images (WSIs), with specific methods including: - TLS Number: Counting the number of Lymphoid Aggregates (LAs) at the tumor Invasive Margin (IM), defining LAs as aggregates of ≥3 lymphocytes. - TLS Maximum Length: Measuring the diameter of the largest LAs at the tumor invasive margin, defining LAs as structures ≥1 mm. - TLS Density: Calculating the ratio of the number of LAs to the length of the tumor invasive margin, defined as TLS density.

3. Immune Cell Infiltration Analysis

To explore the relationship between TLS and immune cell infiltration, the team used Immunohistochemistry (IHC) staining to analyze the density of CD3+ and CD8+ T cells. Artificial Intelligence (AI) algorithms were employed to process the images and quantify immune cell density in the Core of Tumor (CT) and Invasive Margin (IM) regions.

4. Statistical Analysis

The study used Cox proportional hazards models to evaluate the relationship between TLS density and Overall Survival (OS) and plotted survival curves using Kaplan-Meier analysis. Additionally, the study assessed the association between TLS density and other clinicopathological features, such as TNM stage and MSI status.

Research Findings

1. Prognostic Value of TLS Density

The study found that TLS density demonstrated the strongest discriminative performance across all three cohorts. In the primary cohort, the 5-year survival rate for patients with high TLS density was 81.2%, significantly higher than the 69.4% for patients with low TLS density. Similar trends were observed in the validation and TCGA cohorts. Multivariate Cox analysis showed that TLS density was an independent prognostic factor, unrelated to patient age or TNM stage.

2. Relationship Between TLS and Immune Cell Infiltration

High TLS density was significantly associated with high levels of CD3+ T cell infiltration, suggesting that TLS may improve patient prognosis by promoting T cell infiltration. However, no significant difference was observed in CD8+ T cell density between high and low TLS density groups.

3. Relationship Between TLS and Other Clinical Features

In the primary cohort, high TLS density was significantly associated with MSI status, indicating that TLS may play a more critical role in MSI-high colorectal cancer. Additionally, TLS density showed significant prognostic value in stage II patients but not in stage III patients.

Research Conclusions

Through multicenter data analysis, the study identified TLS density as an independent prognostic marker for colorectal cancer patients. TLS density is not only simple to implement but also highly stable and reproducible, providing a new tool for clinical risk stratification in colorectal cancer. Furthermore, the study revealed the relationship between TLS and immune cell infiltration, offering new directions for future immunotherapy research.

Research Highlights

  1. Innovative Methods: The study was the first to use Whole-Slide Images (WSIs) and AI algorithms to quantify TLS, significantly improving the objectivity and reproducibility of TLS assessment.
  2. Multicenter Validation: The study validated the prognostic value of TLS density in three independent cohorts, enhancing the generalizability and reliability of the findings.
  3. Clinical Application Potential: TLS density, as a simple and effective immune prognostic marker, has the potential for widespread application in the diagnosis and treatment of colorectal cancer.

Research Significance

The study not only provides a new biomarker for prognostic assessment in colorectal cancer but also offers important insights into the mechanisms of immune responses within the tumor microenvironment. In the future, TLS density may become a crucial tool for guiding immunotherapy in colorectal cancer and advancing personalized treatment.

Additional Valuable Information

The research team also noted that future studies could further explore the predictive value of TLS in Immune Checkpoint Blockade (ICB) therapy and uncover the molecular mechanisms of TLS formation through multi-omics analysis.