Shinagare AB, et al. - This institutional review board–approved, HIPAA-compliant, retrospective, hypothesis-generating study intended to use machine learning to predict abdominal recurrence on CT on the basis of serial cancer antigen 125 (CA125) levels in patients with advanced high-grade serous ovarian cancer on surveillance. This investigation involved all 57 patients with advanced high-grade serous ovarian cancer who underwent cytoreductive surgery from January to December 2012, followed by surveillance abdominopelvic CT and corresponding CA125 levels. The data presented in this work showed a higher rate of CA125 increase was correlated with abdominal recurrence. The findings suggested that the rate of increase of CA125 could help in the selection of patients who were most likely to benefit from abdominopelvic CT in surveillance of ovarian cancer.