Management and prognosis of cervical cancer patients treated with definitive radiation therapy who have partial metabolic response on post-therapy positron emission tomography

Objective: To describe the management and outcomes of cervical cancer patients initially treated with radiation who had partial metabolic response (PMR) on three-month post-radiation ¹⁸F-fluorodeoxyglucose positron emissions tomography (FDG-PET). Methods: Cervical cancer patients treated with radiation between 1997 and 2013 who had PMR on initial post-therapy FDG-PET were identified from a prospectively maintained database. Descriptive statistics were used to summarize patient demographics, tumor characteristics, surveillance methods, and treatment modalities. Kaplan-Meier methods were used to estimate progression-free (PFS) and overall survival (OS) for patients who underwent cervical biopsy prior to additional therapies and for patients who were managed with chemotherapy, radiation, surgery or no intervention. Results: PMR was identified in 81/542 (15%) women on initial post-radiation PET. Thirty women underwent cervical biopsy, of whom 14 (47%) had persistent cancer. Nine underwent treatment, (three surgery, five chemotherapy alone and one chemotherapy and radiation) but all died of disease; PFS and OS were similar whether women had surgery, chemoradiation therapy, or no treatment. A second surveillance FDG-PET had PPV and NPV of 91% and 75% for progression, respectively, and identified the 19% percent of patients with persistent disease outside of the cervix. Cervical biopsy had a higher PPV (100%) and lower NPV (62.5%) for progression. At the end of the study period, 46 (57%) patients were dead of disease, including all 8 patients (100%) with para-aortic or supraclavicular involvement. Conclusions: If PMR is identified on three-month FDG-PET following completion of radiation for cervical cancer, repeat FDG-PET and/or biopsy are indicated to detect persistence and assist in counseling. PMR predicts poor outcomes, particularly for those with positive cervical biopsies and lymphatic involvement.