Retrospective review of 11C-choline detected thoracic lesions in prostate cancer.

Abstract

325 Background: Prostate cancer recurrence is detected by serum measurements of prostate specific antigen (PSA). Upon PSA elevation, locating sites of recurrence is important to guiding treatment and affecting patient outcomes. The imaging modalities in current practice have varying sensitivities and specificities and often miss early recurrent disease. 11C-choline positron emission tomography (11C-PET) may be able to detect occult disease and guide treatment decisions earlier in the clinical course. We assessed a case series of patients who underwent 11C-PET imaging and were identified to have thoracic disease to estimate the benefit of detection with this modality. Methods: Clinical records were retrospectively reviewed of seventy patients from thoracic oncology teams at Mayo Clinic in Rochester, Minnesota. Patients who had thoracic +/- extra-thoracic metastases on 11C-PET imaging were followed, noting changes in treatment and PSA trends to look for biochemical recurrence of disease. Results: Seventy patients with thoracic metastases discovered on 11C-PET imaging were initially identified. Median time to choline-avid disease from original diagnosis was 82 (IQR: 40-129) months with a median PSA at time of choline of 7.4 (IQR: 3.1-15.7). 11C-PET findings showed 28 patients with metastases limited to the thorax and 42 patients with thoracic and extra-thoracic metastases. After 11C-PET imaging, 1 patient underwent localized therapy only (radiation and surgery), 44 patients underwent systemic therapy only (chemotherapy or hormonal therapy), 19 patients underwent both localized (cryotherapy, radiation, or surgery) and systemic therapy, 3 patients underwent no further treatment, and 3 patients were lost to follow up. After a median follow-up of 36.5 (IQR: 13-52) months, 30 patients had no recurrence and 20 had evidence of biochemical recurrence. For those who underwent local therapy (N=21), 11 had no recurrence of disease. Conclusions: Choline-based imaging may earlier identify metastatic disease that is amenable to local therapy. Further studies are needed to validate the effectiveness of 11C-PET in identifying early, responsive metastatic prostate cancer and its utility in affecting patient outcomes.