To evaluate the utility of positron emission tomography (PET)/computed tomography (CT) early after surgical resection and before postoperative adjuvant radiation therapy.

We studied a prospective cohort of 91 consecutive patients referred for postoperative adjuvant radiation therapy after complete surgical resection. Tumor histologies included 62 squamous cell and 29 non-squamous cell cancers. Median time between surgery and postoperative PET/CT was 28 days (range, 13-75 days). Findings suspicious for persistent/recurrent cancer or distant metastasis were biopsied. Correlation was made with changes in patient care.

Based on PET/CT findings, 24 patients (26.4%) underwent biopsy of suspicious sites. Three patients with suspicious findings did not undergo biopsy because the abnormalities were not easily accessible. Eleven (45.8%) biopsies were positive for cancer. Treatment was changed for 14 (15.4%) patients (11 positive biopsy and 3 nonbiopsied patients) as a result. Treatment changes included abandonment of radiation therapy and switching to palliative chemotherapy or hospice care (4), increasing the radiation therapy dose (6), extending the radiation therapy treatment volume and increasing the dose (1), additional surgery (2), and adding palliative chemotherapy to palliative radiation therapy (1). Treatment for recurrent cancer and primary skin cancer were significant predictors of having a biopsy-proven, treatment-changing positive PET/CT (p < 0.03).

Even with an expectedly high rate of false positive PET/CT scans in this early postoperative period, PET/CT changed patient management in a relatively large proportion of patients. PET/CT can be recommended in the postoperative, preradiation therapy setting with the understanding that treatment-altering PET/CT findings should be biopsied for confirmation.