ColoCare Study - Colorectal Cancer Cohort

This trial is following people newly diagnosed with colon or rectal cancer to study how lifestyle, diet, the environment, and biological factors affect cancer survival, recurrence, and quality of life over time. **You may be eligible if...** - You are between 18 and 89 years old (for recent participants, 18–69 years old) - You are male or female - You have been newly diagnosed with colon or rectal cancer (stages I–IV) - You speak English (at most sites) or German (at the University Hospital Heidelberg) - You are mentally and physically able to give consent and participate **You may NOT be eligible if...** - You do not meet the above criteria - You are unwilling to participate in follow-up Talk to your doctor to see if this trial is right for you.