Tumour Deposit Count is an Independent Prognostic Factor in Colorectal Cancer—A Population-Based Cohort Study
Colorectal Cancer (CRC) is the third most common malignant tumor worldwide, and its prognosis assessment primarily relies on the TNM staging system. However, the current TNM staging system does not fully account for the presence and count of Tumor Deposits (TDs) in lymph node-positive colorectal cancer. Tumor deposits refer to discrete tumor nodules located within the colorectal mesentery, lacking identifiable lymphatic, vascular, or neural structures. Although multiple studies have shown that tumor deposits are closely related to overall survival and distant metastasis risk in lymph node-negative colorectal cancer, the TNM system does not assign the same prognostic value to tumor deposits in lymph node-positive patients. Additionally, the prognostic significance of multiple tumor deposits has not been adequately addressed.
To address this issue, Simon Lundström and his team conducted a large-scale cohort study based on the Swedish Colorectal Cancer Registry, aiming to explore the independent prognostic value of tumor deposit count in colorectal cancer patients and advocating for its inclusion in future TNM staging systems.
Source of the Study
The research was conducted by a team from Skåne University Hospital and Lund University in Sweden, with primary authors including Simon Lundström, Erik Agger, Marie-Louise Lydrup, Fredrik Jörgren, and Pamela Buchwald. The study was published in 2025 in the British Journal of Surgery (BJS) under the title “Tumour deposit count is an independent prognostic factor in colorectal cancer—a population-based cohort study.”
Research Process
Study Subjects and Data Source
The research team extracted data from the Swedish Colorectal Cancer Registry for patients who underwent curative surgery for colorectal cancer between 2016 and 2019. Initially, 18,913 patients were included, and after excluding those who did not meet the criteria (e.g., synchronous or metachronous colorectal cancer, non-curative surgery, stage IV disease), 14,154 patients were ultimately analyzed. Among them, 12% (1,702 patients) had tumor deposits.
Data Stratification and Analysis
Patients were stratified based on tumor deposit count (0, 1, 2, 3, 4, and ≥5). The primary endpoints of the study included Overall Survival (OS), Distant Metastasis (DM), and Local Recurrence (LR). Univariable and multivariable Cox regression analyses were used, adjusting for confounding factors such as age, sex, neoadjuvant treatment, and the number of positive lymph nodes.
Statistical Methods
Kaplan-Meier curves were used to calculate 5-year cumulative survival rates and risks, with differences between groups compared using the Log-rank test. Multivariable Cox regression analysis further validated the independent prognostic value of tumor deposit count. Additionally, sensitivity and subgroup analyses were conducted to assess the impact of tumor deposit count in different tumor locations (colon cancer vs. rectal cancer).
Key Findings
Relationship Between Tumor Deposit Count and Prognosis
The study found that as tumor deposit count increased, patients’ 5-year overall survival rates significantly declined (no tumor deposits: 79%; 1 deposit: 70%; 2 deposits: 61%; 3 deposits: 66%; 4 deposits: 50%; ≥5 deposits: 49%). Simultaneously, the risk of distant metastasis progressively increased (no tumor deposits: 14%; 1 deposit: 26%; 2 deposits: 35%; 3 deposits: 41%; 4 deposits: 48%; ≥5 deposits: 54%). Although the risk of local recurrence was lower, a similar trend was observed.
Multivariable Cox Regression Analysis
In the multivariable Cox regression analysis, tumor deposit count remained an independent negative prognostic factor for overall survival and distant metastasis. Even after adjusting for age, sex, neoadjuvant treatment, and the number of positive lymph nodes, the impact of tumor deposit count remained significant.
Subgroup Analysis
Subgroup analysis showed that tumor deposit count had similar prognostic value in both colon and rectal cancer patients, further validating its broad applicability in colorectal cancer.
Research Conclusion
The study is the first to confirm that tumor deposit count is an independent negative prognostic factor for overall survival and distant metastasis in colorectal cancer patients, independent of lymph node status. The findings suggest that tumor deposit count should be incorporated into the TNM staging system, regardless of the presence of positive lymph nodes, to improve the accuracy of prognosis assessment.
Highlights of the Study
- Large-Scale Cohort Study: Based on the nationwide Swedish Colorectal Cancer Registry, the study has a large sample size and high data quality, making the results broadly representative.
- Independent Prognostic Value: The study is the first to clearly establish the independent prognostic value of tumor deposit count in colorectal cancer, filling a gap in the current TNM staging system.
- Clinical Significance: The study advocates for the inclusion of tumor deposit count in the TNM staging system, providing clinicians with a more accurate prognosis assessment tool to optimize treatment decisions.
- Multidimensional Analysis: The study not only evaluated overall survival but also analyzed the risks of distant metastasis and local recurrence, offering comprehensive prognostic information.
Other Valuable Information
The study also noted that although preoperative imaging diagnosis of tumor deposits has potential value, it currently does not significantly improve patient outcomes. Future research should focus on the etiological mechanisms of tumor deposits to explore new therapeutic targets and improve the prognosis of this patient group.
Summary
The research by Simon Lundström’s team provides a new perspective on the prognosis assessment of colorectal cancer, emphasizing the importance of tumor deposit count in the TNM staging system. This discovery not only holds significant scientific value but also offers practical guidance for clinical practice, potentially improving the treatment and prognosis of colorectal cancer patients in the future.