# Tumor Deposits in Non-Metastatic Colorectal Cancer as a Risk Factor of Peritoneal Metastasis

## TL;DR

Tumor deposits in non-metastatic colorectal cancer are linked to a higher risk of peritoneal metastasis and worse outcomes, suggesting they are an important but overlooked prognostic factor.

## Contribution

This study demonstrates that tumor deposits independently predict peritoneal metastasis better than lymph node metastasis in colorectal cancer.

## Key findings

- Patients with tumor deposits had a significantly higher global recurrence rate (60.8%) compared to those without (17.8%).
- Tumor deposits were strongly associated with peritoneal metastasis (OR: 7.511) and outperformed lymph node metastasis in predicting it.
- In stage III colorectal cancer, tumor deposits were linked to a 26.1% peritoneal metastasis rate versus 10.9% without.

## Abstract

Background: Although tumor deposits (TD) have been known for almost a century, their origin and mode of spread remain controversial. The main objective is to analyze the prognostic value of tumor deposits in non-metastatic colorectal cancer as a risk factor of global recurrence, locoregional recurrence, liver and lung metastasis and specially for peritoneal metastasis (PM).

Methods: This study analyzed 1,425 non-metastatic colorectal cancer patients. Four groups were built, according to the presence or absence of Lymph Node Metastasis (LNM) or TD.

Results: The global recurrence rate in patients with TDs was significantly higher than those without TDs (17.8% vs 60.8%; p<0.001). Patients with TDs had a lower survival and suffered higher rates of liver metastasis (8.6% vs 26.7%; p<0.001); OR of 4.244 (95% CI: 3.004-5.994) and lung metastasis (7.4% vs 19.3%; p<0.001); (OR 3.585;95% CI: 2.397-5.362). However, the main differences were found in PM (4.7 % vs 26.1 %; p<0.001); (OR: 7.511 (95% CI:5.092-11.079). Distribution by groups shows that patients with TD and LNM had a higher rate of PM. Patients with TD without any LMN had higher PM rate than those with LNM without TD. In stage III, patients with TD suffered higher rates of PM, (26.1% vs 10.9%); p< 0.001). OR: 3.075 (95% CI: 1.969-4.803).

Conclusions: The presence of TD increases the risk of peritoneal metastasis. Patients with TD without LNM had higher rate of peritoneal metastasis than those with LNM without TD. TD have independent prognostic value and provide complementary information. Prognostic value of TDs is underestimated in the current TNM system.