The purpose of surveillance is to detect recurrences that might still be potentially curable.
High risk patients generally relapse within 2-3 years, while low-risk patients may relapse later, although it is less likely. Relapses most commonly occur in the lungs. Early detection of local or metastatic recurrence to the lungs may have prognostic implications when these are early enough to be resected.
Therefore, patients who are suitable for further surgery can undergo routine surveillance to detect early recurrence. There is limited data on effective surveillance strategies.
Examples of guidelines include:
European Society for Medical Oncology (ESMO) guidelines:
High risk patients are followed: every 3 to 4 months in first 2-3 years then twice a year to year 5, then annually.
Low grade sarcoma: local relapse surveillance every 4 to 6 months and CXR or CT at longer intervals in first 3-5 years, then annually.
For more details:https://www.esmo.org/Guidelines/Sarcoma-and-GIST/Soft-Tissue-and-Visceral-Sarcomas
National Comprehensive Cancer Network (NCCN) guidelines:
History and Physical examination, chest imaging (CT preferred) and imaging of surgical site: every 3 to 6 months in first 2-3 years, every 6 months during years 4-5 and then annually