Pelvic insufficiency fractures in locally advanced cervical cancer: the diagnostic yield of post-treatment MRI in a tertiary centre

To assess the incidence of pelvic insufficiency fractures (PIFs) after concurrent chemoradiotherapy (CCRT) in patients with locally advanced cervical cancer (LACC), their time of onset and risk factors. We also analysed the inter-observer agreement between gynaecologic radiologists (GYN readers) and radiologists expert in musculoskeletal imaging (MSK reader) in detecting PIFs in our tertiary care centre. Patients with confirmed LACC who underwent concurrent chemoradiation (CCRT) at our institution from June 2019 to November 2022 were retrospectively included. These patients underwent follow-up pelvic MRI every 3-6 months after CCRT. Cohen's kappa statistics was employed to assess the inter-observer agreement between GYN and MSK readers.Logistic regression analysis was performed calculating odds ratios (OR) to identify risk factors for PIFs, such as age, body mass index (BMI), diabetes, smoking, hypertension, renal function and tumour size. Eighty-seven patients were included. PIFs were diagnosed in 21/87 (24.1 %) patients with a median onset time of 7.4 months from the end of EBRT. Among risk factors, age was statistically associated with PIFs (OR = 1.057, 95 % CI: 1.005-1.118, p = 0.033) with median age in the fracture group of 61.1 years (range: 52.0-71.5) and 53.8 years (range: 43.8-63.3). BMI was a significant predictor of PIFs (OR = 1.134; 95 % CI: 1.013-1.285; p = 0.027), with a higher median BMI among patients with PIFs (26.5; range: 21.5-31.2) compared to non-fractured patients (23.1; range: 20.2-25.1). Also patients with reduced renal function (eGFR < 60 mL/min) had 3.437 times higher odds of experiencing fractures compared to those with normal eGFR. The GYN readers correctly identified PIFs in 2/21 cases and agreed with the MSK reader in 68/87 cases. The interobserver agreement was poor to fair (K = 0.138; 95 % CI: 0-0.311). PIFs are a common complication of CCRT. Their identification on post-CCRT MRI may decrease the need for further targeted investigations and invasive treatments.