Pretreatment risk factors for parametrial involvement in FIGO stage IB1 cervical cancer

OBJECTIVE All patients with stage IB1 cervical cancer do not need to undergo parametrectomy. Some low-risk criteria for parametrial involvement (PI) have been proposed based on pathological findings. The aim of this study was to determine pretreatment risk factors for PI in stage IB1 cervical cancer. METHODS We retrospectively reviewed 115 patients with stage IB1 cervical cancer who underwent radical hysterectomy or radical trachelectomy. Magnetic resonance imaging (MRI) was performed and serum concentrations of squamous cell carcinoma antigen (SCC-Ag) and cancer antigen 125 (CA-125) were determined in all patients before initial treatment. The following pretreatment factors were investigated: histological variant, maximum tumor diameter, tumor volume (volume index), pelvic lymph node enlargement, and serum tumor markers. Logistic regression analysis was used to select the independent risk factors for PI. RESULTS Eighteen of the 115 patients (15.7%) were pathologically diagnosed with PI. Multivariate analysis confirmed the following independent risk factors for PI: MRI-based tumor diameter ≥ 25 mm (odds ratio [OR], 9.9; 95% confidence interval [CI], 2.1 to 48.1), MRI-based volume index ≥ 5,000 mm³ (OR, 13.3; 95% CI, 1.4 to 125.0), and positive serum tumor markers SCC-Ag ≥ 1.5 ng/mL or CA-125 ≥ 35 U/mL (OR, 5.7; 95% CI, 1.3 to 25.1). Of 53 patients with no risk factors for PI, none had PI. CONCLUSION Less radical surgery may become one of the treatment options for stage IB1 cervical cancer patients with MRI-based tumor diameter <25 mm, MRI-based volume index <5,000 mm³, and negativity for SCC-Ag and CA-125.