Value of PET scan in patients with retroperitoneal sarcoma treated with preoperative radiotherapy

Preoperative radiotherapy provides advantages in the management of retroperitoneal sarcoma (RPS). We describe our experience treating a cohort who underwent pre- and post-radiotherapy functional imaging with FDG-PET scan.

Consecutive patients presenting between January 1999 and December 2009 with a diagnosis of either primary or recurrent RPS were identified from the hospital patient record database using ICD codes, and cross-referenced with the completed radiotherapy course database. Those patients suitable for preoperative radiotherapy and surgery who underwent both pre- and post-radiotherapy FDG-PET were included. Exclusions included presence of metastatic disease, age under 18 years and/or paediatric histology, and treatment with palliative intent.

Eleven patients were included, of whom six were male. Median age was 63 years (range, 38-78 years). The majority of patients had Stage T2b, high-grade disease. Ten patients were treated at initial presentation and one at first local recurrence. A malignant diagnosis was confirmed in all patients who underwent CT-guided core biopsy; a diagnosis of sarcoma was reached in 91%. Sensitivity of FDG-PET imaging was 100%. Metabolic partial or complete response did not correlate with change in tumour size, nor pathological response assessment. Pulmonary and hepatic metastatic disease was detected in one patient on post-treatment imaging. All patients in the cohort completed preoperative radiotherapy. There was no grade 3 or 4 toxicity. Sixty-four percent proceeded to radical resection. Complete macroscopic excision was achieved in all cases. There was no perioperative mortality.

Combined therapy with preoperative radiotherapy and surgery has acceptable levels of toxicity. CT-guided core biopsy is an accurate means of confirming a diagnosis of RPS prior to definitive treatment. Utility of PET scan in the management of RPS is evolving and further investigation is warranted.