Colorectal cancer (CRC) is one of the most common and deadly cancers worldwide. About 1 in 4 people with CRC already have cancer spread (metastasis) when first diagnosed, and about half develop spread during their illness. Recent research shows that bacteria living in the gut and even within tumors might play an important role in how cancer spreads. The goal of this study is to better understand how bacteria might influence the spread of colorectal cancer. The main questions we aim to answer are: Are there differences in bacteria between people whose cancer has spread and those whose cancer has not spread? Could certain bacteria help predict which cancers might spread? To answer these questions, we will: Collect different types of samples from participants: Tumor tissue Normal tissue near the tumor Tissue from where cancer has spread Stool samples before surgery Study the bacteria in these samples using advanced testing methods Compare bacterial patterns between different groups People can take part in this study if they: Are between 18 and 75 years old Have colorectal cancer confirmed by doctors Have not taken antibiotics recently Do not have immune system problems This research may help us: Understand why some colorectal cancers spread Find new ways to predict which cancers might spread Develop better treatments for colorectal cancer