Oncologists cannot guarantee cancer will never recur, but they use tumor biology, treatment response, and evidence-based surveillance protocols to stratify individual risk and detect recurrence when it is most treatable. Key Takeaways Doctors stratify recurrence risk using tumor biology markers (ER/PR, HER2, MSI), cancer stage, and treatment response rather than offering guarantees Surveillance intensity varies by cancer type: high-risk cancers require scheduled CT scans ever