High Versus Lower Intensity Surveillance Following Resection of Retroperitoneal Sarcoma

Inclusion Criteria: * Adult patients (greater than 18 years) * Primary resection * Histologically confirmed retroperitoneal, abdominal or pelvic soft tissue sarcoma * R0/R1 resection * Eligible whether or not the participant undergoes neoadjuvant treatment Exclusion Criteria: * Metastatic disease at time of randomisation * Recurrent, metastatic or residual disease identified on baseline CT imaging (3-4 months post primary resection) * Reoperation for recurrent soft tissue sarcoma * Re-resection following previous inadequate surgery * R2 resection * Patients receiving adjuvant therapy that will delay, interrupt or render radiological surveillance unpredictable * Uterine sarcomas, gastrointestinal stromal tumour (GIST), fibromatosis, epithelial tumours, multifocal disease, sarcomas of bony origin * Patient declined to consent to data sharing with RESAR (unless in a centre contributing via pre-planned IPDMA)