Advanced imaging biomarkers in endometrial cancer

• Main Author: Ytre-Hauge, Sigmund
• Format: Dissertation
• Language: English

Background: Endometrial cancer is the most common gynecological cancer in highdeveloped regions of the world, and the incidence has been increasing over the last half century, largely driven by a concurrent increase in population obesity. Primary treatment is surgical in most cases, but only limited preoperative risk stratification has been applied in traditional clinical practice. To enable more individualized treatment, improved methods for preoperative tumor characterization are highly warranted. Aim: To identify and evaluate new imaging markers that may aid in the preoperative risk stratification and tailoring of treatment in endometrial cancer. Material and methods: The studies included in this thesis are based on collected imaging-, clinical- and histological data from endometrial cancer patients treated at Haukeland University Hospital during April 2009 to November 2013. Standardized MR imaging data were acquired for 216 prospectively included patients with histologically confirmed endometrial cancer. From this cohort, four different subcohorts were included in study I-IV. In Paper I, three radiologists independently measured tumor size on conventional MR images for 212 patients. In Paper II, metabolic features were extracted from MR spectroscopy performed on 77 patients. In Paper III, texture features were extracted from MR images, using a filtrationhistogram technique in 180 patients. In Paper IV, CT imaging data were retrospectively collected and texture features extracted for 155 patients. In all studies, the respective imaging markers were evaluated as predictors of histopathological highrisk features and survival. Results: The interobserver variability for MRI-measured tumor size is very low (ICC 0.78-0.85) (Paper I). AP diameter greater than 2 cm independently predicts deep myometrial invasion (OR 6.7, p< 0.001) and CC diameter greater than 4 cm independently predicts lymph node metastases (OR 4.9, p=0.009) when adjusting for conventional MRI reading results and risk status based on preoperative endometrial biopsy (Paper I). CC tumor diameter has an independent impact on recurrence- and progression-free survival (adjusted HR 1.04, p=0.009) (Paper I). Tumor tissue has significantly higher MR spectroscopy-derived ratios for tCho/Creatine, tCho/Water and tCho/Noise than normal myometrial tissue (p