Correlation of Post-Treatment Biopsy and Fluorodeoxyglucose PET/CT Findings Following Definitive Chemotherapy and Radiation for Cervical Cancer

Abstract

Concurrent chemotherapy and external beam radiation with brachytherapy boost is considered standard of care for treatment of locally advanced cervical cancer. Post treatment surveillance fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging is recommended 3-6 months after completion of therapy. Persistent FDG avidity is commonly observed at the cervix on surveillance scans, indeterminate for residual malignancy versus post treatment inflammatory change. To better understand the clinical significance of residual hypermetabolic activity, we performed an analysis of surveillance FDG-PET/CT images, correlating findings with post treatment cervical biopsy results after completion of therapy. The medical records of all patients treated with definitive chemotherapy and radiation for locally advanced (FIGO IB3 to IVA) cervical cancer at a single academic medical center between 2017 and 2022 were reviewed. Patients were treated with curative intent using a combination of pelvic external beam radiation with concurrent cisplatin chemotherapy followed by intracavitary or combined intracavitary/interstitial brachytherapy boost. Patients underwent FDG-PET/CT imaging at 3-6 months upon completion of therapy, followed by biopsy either for suspected residual disease or equivocal findings on physical exam or FDG-PET/CT scans. Biopsies were obtained within 100 days of FDG-PET/CT imaging (median, 14 days). Twenty-three patients met inclusion criteria. One patient was excluded from analysis due to lack of FDG avidity on her pre-treatment FDG-PET/CT. Among the 22 evaluable scans, median pre-treatment FDG- PET/CT SUVmax of the cervix was 16.3 (range, 4.9-55). Median post-treatment SUVmax was 4.4 (range, 2.1-7.4). Median change in SUVmax from pre-treatment to post-treatment was 11.8 (range, 1.1 to 50.6). Twenty patients had a post-treatment SUVmax of greater than 3. Among post treatment scans, eight showed no residual uptake; two showed uptakes equal to the liver; eleven showed uptakes moderately higher than liver; and one showed uptake markedly increased relative to liver. None of the biopsy specimens showed evidence of residual malignancy, instead showing fibroinflammatory necrosis and reactive changes. None of the patients developed clinical evidence of disease progression at the cervix within one year of treatment completion. Residual hypermetabolic activity at the cervix is common following definitive chemotherapy and radiation for cervical cancer. This is unlikely to represent residual viable malignancy. Post treatment FDG-PET/CT imaging remains valuable for detecting locoregional or distant disease progression/persistence following therapy.