Response assessment and follow-up by imaging in gyn tumours

Abstract

Imaging plays an important role in the staging and management of all main gynaecological tumours. Gynaecological tumours treated primarily with radiotherapy such as cervical, vaginal or vulvar cancer typically show considerable tumour shrinkage during treatment. Following the successful completion of initial treatment, there is no strong evidence to support posttreatment imaging surveillance of asymptomatic women. In general, gynaeco-oncological practice, the initial suspicion of disease relapse relies largely on clinical symptoms rather than radiological evidence. However, once clinical relapse is suspected, imaging plays a crucial role in planning salvage therapy. Typical treatment concepts in locally advanced (non-tubo-ovarian) gynaecological cancers consist of external beam radiotherapy (EBRT) and concomitant chemotherapy followed by brachytherapy. Due to the substantial tumour shrinkage during external beam radiotherapy, the GYN GEC-ESTRO group defined an adaptive target volume concept for MRI-based brachytherapy. So far, target concepts for cervical and vaginal cancer were elaborated. The integration of functional imaging into the delineation process could help to reduce interobserver variations and further differentiate subvolumes with increased risk for recurrence. In cervical cancer, MRI performed at 6 months post end of RT, the cervix should be normal or small in size and of low T2 signal intensity, with no evidence of restricted diffusion, to suggest a complete response. [18F]FDG PET/CT has been shown to be a strong predictor of patient outcome, with better survival outcomes in patients with a complete metabolic response. Imaging plays an essential role when recurrence is suspected. The initial steps will involve confirmation of the relapse, defining the extent of disease and determining the available treatment options. If there is no substrate for rising markers on CT or MRI, an [18F]FDG PET/CT should be performed due to its high sensitivity and specificity in early recurrence detection. Isolated vaginal recurrences are a typical pattern of failure in gynaecological malignancies, in particular for endometrial cancer. Treatment strategies follow the similar principles as for primary vaginal cancer.