[18F]FDG-PET/CT monitoring early identifies advanced ovarian cancer patients who will benefit from prolonged neo-adjuvant chemotherapy.

AIM: The most accepted standard duration of neoadjuvant chemotherapy (na-CHT) before debulking surgery for advanced ovarian cancer (AOC) is 3 courses. However a percentage of patients could benefit from additional courses. [(18)F]FDG-PET/CT monitoring during na-CHT could predict early pathological response and allow the delivery of an optimal na-CHT duration. METHODS: Consecutive patients with AOC unsuitable for optimal up front surgery and fit for na-CHT were monitored by FDG-PET/CT at baseline and after 3 and 6 courses of carboplatin-paclitaxel CHT. At the end of na-CHT patients were re-evaluated to undergo definitive optimal surgery (i.e. without post-surgical residual disease). Percentage changes in maximal standardized uptake value (∆-SUVmax) were compared with the pathological response. Only patients with pathological complete response (pCR) or minimal residual disease (pMRD) were considered as pathological responders (pR), while all the other cases were considered non-responders (NR). RESULTS: Baseline FDG-PET/CT was abnormal in all 42 enrolled patients (median SUVmax 11, range 3-20). After 3 and 6 courses median SUVmax decreased to 3 (<2-21) and <2, i.e. value equal to normal surrounding tissues uptake (<2-17), respectively. After 3 courses, 17 (40%) patients presented ∆-SUVmax=100%, (i.e. SUVmax <2): 15 of them (88%) subsequently resulted pR and achieved no postsurgical residual disease at the end of na-CHT, while 2 (12%) were NR with postsurgical residual tumor ≤ 1cm. Out of 25 patients with ∆-SUVmax <100% after 3 courses, 6 (24%) were pR and 19 (76%) NR at the end of na-CHT. CONCLUSION: Patients with AOC who present normalization of SUVmax after 3 courses of na-CT have a high likelihood of benefiting from 3 additional courses in order to obtain pCR or pMDR and receiving optimal surgery.