Primary Retroperitoneal Tumors

This chapter reviews primary retro­peritoneal sarcomas (RPS), which encompass about one third of all primary retroperitoneal tumors. The vast majority do not have any identifiable predisposing cause, but the history of radiation exposure and genetic syndromes are sometimes implicated. The eighth edition American Joint Committee on Cancer (AJCC) staging system changed significantly for STS and now has a separate staging system for RPS and is based on a combination of anatomic as well as pathologic data.Tumors that are small or low-grade are unlikely to metastasize and are therefore, well managed with surgery with or without radiation therapy. Large or high-grade tumors have a greater propensity for metastases and need to be discussed in a multidisciplinary conference to determine the appropriateness of systemic therapy and the most beneficial sequence (preoperative vs. postoperative), acknowledging that the standard of care is complete surgical resection. Radiation therapy is sometimes employed for primary local management in an effort to improve local control of these tumors.Successful management of RPS requires the collaborative efforts of the radiologist, pathologist, radiation oncologist, medical oncologist, surgical oncologist, and other specialists. Imag­ing plays a key role in the initial detection, therapeutic planning, and follow-up of these patients. RPS presents a challenge in management because of tumor heterogeneity, location, local invasion, and propensity for local recurrence. Surgical therapy offers the best hope for cure; however, even with aggressive resection, recur­rence occurs frequently.