Objectives The aims of study were to determine the predictive value of preoperative magnetic resonance imaging (MRI) for parametrial invasion (PMI) and to develop a predictive model for PMI in patients with stage IB1 to IIA2 cervical cancer.

Methods We retrospectively analyzed patients with stage IB1 to IIA2 cervical cancer (n = 215) who underwent radical hysterectomy between 2003 and 2014. The presence of PMI from postoperative pathological reports and its association with preoperative MRI findings were evaluated. We developed a predictive model for PMI using independent predictive factors identified by logistic regression and estimated its predictive performance.

Results Thirty patients (14.0%) had PMI from postoperative pathological reports. Among the preoperative MRI findings, a greater tumor diameter (4.2 vs 2.0 cm; P < 0.001), a larger tumor volume (92.6 vs 12.7 cm³; P < 0.001), the presence of PMI (53.3% vs 8.6%; P < 0.001), and upper vaginal involvement (73.3% vs 22.7%; P < 0.001) were significantly associated with PMI. Multivariate analysis identified tumor volume (odds ratio, 7.0; 95% confidence interval, 2.63–18.53; P < 0.001) and PMI (odds ratio, 6.1; 95% confidence interval, 2.31–15.97; P < 0.001) from preoperative MRI findings as independent predictive factors for PMI. Our predictive model demonstrates that the presence of PMI or a tumor volume of greater than 18.0 cm³ has a higher sensitivity (86.7% vs 53.3%) and lower specificity (74.6% vs 91.4%) than the presence of PMI alone. Specifically, the model's negative predictive value was superior to that of PMI only (97.2% vs 92.3%). In the low-risk group, defined as preoperative MRI findings suggesting no PMI and a tumor volume of 18.0 cm³ or less, the proportion of false negative cases was just 2.8%.

Conclusions When tumor volume with findings suggesting that PMI is considered, preoperative MRI is useful in excluding PMI. A predictive model based on preoperative MRI findings seems to be valuable in identifying potential candidates for less radical surgery in stage IB1 to IIA2 cervical cancer.