Role of FDG-PET in the management of gestational trophoblastic neoplasia (GTN)

Objectives: To evaluate the role of FDG-PET and PET/CT in staging, monitoring treatment efficacy and impact on patients management in GTN patients. Methods: 38 patients referred to our institution for GTN treatment between 2004 and 2011 were retrospectively enrolled. During staging all patients underwent to ?HCG measurements, trans-vaginal ultrasound(TV-US), Chest X-ray, whole-body CT and PET/CT (n= 32) or PET (n= 6). 8 patients with positive extra-uterine PET/CT basal study were re-evaluated by a second PET/CT after ?HCG normalization. PET(n=1) or PET/CT(n=3) were repeated in patients with ?HCG resistance. TV-US and whole-body CT were used as standard of reference. Results: Staging: PET or PET/CT correctly identified uterine disease in 22/25 patients(88%), lung metastases in 12/19(63%) patients, lymphnodal involvement in 2/2 patients, ovarian metastases in 1/1, pancreatic metastases in 1/1 and liver metastases in 2/4(50%) patients. Restaging: in 8/8 patients with extra-uterine disease during staging, PET/CT documented complete response to therapy after ?HCG normalization. PET and PET/CT identified the sites of persistent disease in all ?HCG resistance patients (n=4), leading to tailored treatment: 2/4 patients underwent to second line chemotherapy and in 2/4 patients surgical removal of resistant disease (lung and uterus) was performed. Conclusions: During staging of GTN, PET has low sensitivity and high specificity. During treatment monitoring PET may detect a complete response to chemotherapy earlier than CT. In patients with resistant disease to chemotherapy PET may play a role in changing management and guiding treatment