Value of magnetic resonance and ¹⁸FDG PET-CT in predicting tumor response and resectability of primary locally advanced cervical cancer after treatment with intensity-modulated arc therapy: a prospective pathology-matched study.

OBJECTIVE: To report on the value of magnetic resonance imaging (MRI) and 2-deoxy-2-[18] fluoro-D-glucose positron emission tomography computed tomography (¹⁸FDG PET-CT) in predicting resectability and pathological response of primary locally advanced cervical cancer after neoadjuvant intensity-modulated arc therapy (IMAT) with or without cisplatin (C).

METHODS AND MATERIALS: Twenty-seven patients with International Federation of Gynecology and Obstetrics stages IB2 to IVA cervical cancer were treated with IMAT-C followed by extrafascial hysterectomy (EH). All patients received MRI and ¹⁸FDG PET-CT after IMAT-C. The end points of this study were to: 1. Assess the ability of MRI to predict negative surgical margins (R0). 2. Assess the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MRI in predicting the following situation at the EH specimen: "no residual disease or minimal microscopically visible residual tumor." 3. Assess the sensitivity, specificity, PPV, and NPV value of ¹⁸FDG PET-CT in predicting "no residual viable tumor cells" at the EH specimen.

RESULTS: An R0 resection was obtained in all patients. None of the EH specimens contained macroscopically visible tumor. In 13 patients, no viable tumor cells were found and only 14 had residual microscopic disease. Twenty-four of 27 MRIs were able to correctly predict R0 resection. A negative MRI was 100% predictive for the end point "R0 resection." The specificity and NPV of MRI (end point 2) were 74% and 100%, respectively. No sensitivity or PPV could be calculated. The sensitivity, specificity, PPV, and NPV of ¹⁸FDG PET-CT were 29%, 62%, 44%, and 44%, respectively (end point 3).

CONCLUSIONS: A negative MRI after IMAT-C predicts 100% correctly for R0 resection. The role of FDG PET-CT in predicting viable tumor cells at EH specimen is at least debatable.