Surveillance AFter Extremity Tumor surgerY

Inclusion Criteria: * The patient is 18 years of age or older; * The patient has been diagnosed with a primary extremity grade II or III soft-tissue sarcoma (STS); * The patient has undergone surgical excision of the tumor with curative intent and with no evidence of gross residual disease based on the pathology report; * The patient has completed all planned neoadjuvant or adjuvant radiation and / or chemotherapy, if applicable; * The tumor size is greater than or equal to (≥) five centimeters according to the pathology report or based on the pre-treatment MRI if neoadjuvant radiation and / or chemotherapy are given; and * The patient provides informed consent. Exclusion Criteria: * The patient has metastases at initial presentation based on the radiology report of the initial thoracic imaging†; * The patient has recently undergone surgical excision of a local recurrence; * The patient has been diagnosed with one of the special sub-types, myxoid / round cell liposarcoma or extra-skeletal Ewing's sarcoma\*; * The patient has been previously diagnosed with a genetic syndrome with an elevated risk of malignancy, such as Li-Freumeni Syndrome‡; * The patient has been previously diagnosed with a co-morbid condition that has a life expectancy of less than (\<) one year; * The site-specific surveillance protocol for the patient's disease is not compatible with the study protocol (i.e., regular planned whole-body imaging with positron emission tomography \[PET\] scans); * Likely problems, in the judgment of the investigator, with the patient maintaining follow-up (with the specific reasoning requiring approval of the Methods Center); * The patient is currently enrolled in a study that does not permit co-enrolment; and * The patient has already been enrolled in the SAFETY trial. * A second CT scan may be required to confirm that indeterminate nodules are false positives before the patient can be enrolled (provided that the second CT scan shows no evidence of metastatic disease); * Myxoid liposarcoma and extra-skeletal Ewing's sarcoma have different metastatic patterns, which necessitate different surveillance protocols; * Individuals with Li-Freumeni Syndrome, or other genetic syndromes with an elevated risk of malignancy, appear to be at an elevated risk for radiation-induced cancers, so the use of CT scans should be limited.