After treatment of primary soft tissue sarcoma, a third of patients will develop local or distant (lung in 90% of cases) recurrence. For an individual patient, the issue of cancer recurrence is a binary event. However, when developing surveillance strategies for large groups of patients, knowledge of the risks (tumor biology, natural history of the disease), the benefits (potential efficacy of salvage therapy) and diagnosis test performances is necessary to formulate a rationale and resource effective follow-up algorithm.