Relation between FIGO stage, primary tumor volume, and presence of lymph node metastases in cervical cancer patients referred for radiotherapy

The aims of this study were to determine, firstly, the relationship between FIGO stage and various tumor parameters determined by magnetic resonance imaging (MRI), and, secondly, whether any of these parameters were predictors of lymph node metastases as determined by fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) in cervical cancer patients referred for radiotherapy. In 70 consecutive patients, both PET and MRI visualized all primary tumors except for one previously removed by cone biopsy. While clinical diameter and MRI-derived diameter showed a significant relationship between these two measurements (r = 0.70; P < 0.001) there was a large variability in MRI diameter for each FIGO stage and wide overlap. The average volume of primary cervical tumor on MRI was 60 cc (5-256). In FIGO stages, I, II, III and IV, uterine body involvement was present in 58%, 73%, 88%, and 100% of 19, 30, 16, and 5 patients, respectively (P-trend= 0.015). Node positivity on FDG PET was present in 11% of patients without uterine body extension, but increased to 75% in those with uterine involvement. Average tumor volume in node-negative patients was 49 cc (5-186). Average tumor volume in node-positive patients was 69 cc (8-256). There was a significant association between nodal involvement and both FIGO stage (P = 0.018) and uterine body involvement (P < 0.001), but tumor volume and longitudinal MRI diameter were not statistically significant in unifactor predictors of nodal involvement. In multivariate analysis only uterine body extension, however, was independently related to the risk of nodal involvement. In conclusion, MRI provides noninvasive tumor size evaluation and can also demonstrate invasion of the uterine body that appears to be associated with an increased risk of nodal metastasis. This may provide clinically important prognostic information not available from current FIGO staging.