Prediction of Micrometastasis (< 1 cm) to Pelvic Lymph Nodes in Prostate Cancer: Role of Preoperative MRI

Abstract

Objective: The purpose of this study was to retrospectively investigate whether preoperative MRI plays a key role in clinical prediction of micrometastasis (< 1 cm) to pelvic lymph nodes in prostate cancer.

Materials and methods: One hundred one patients with prostate cancer who underwent preoperative MRI and radical prostatectomy with pelvic lymph node dissection were included. None of the patients had a pelvic lymph node with a short-axis diameter of 1 cm or larger on MRI. Both clinical (prostate-specific antigen, biopsy Gleason score, greatest percentage of biopsy core, and percentage of positive cores) and MRI parameters (tumor apparent diffusion coefficient and tumor staging) were assessed. The univariate, multivariate, and ROC curve analyses were conducted.

Results: Of 101 patients, nine (8.9%) had pelvic lymph node metastases. In univariate analysis, all of the clinical and MRI parameters were related to micrometastasis to pelvic lymph nodes (p < 0.05). However, multivariate analysis revealed that only preoperative MRI stage was significant (p = 0.044). AUC of preoperative MRI stage was 0.954 (odds ratio, 21.7). Respective sensitivity and specificity of preoperative tumor staging by MRI were 100% and 65.2% with cutoff of T3a or more, and 88.9% and 94.6% with cutoff of T3b for predicting micrometastasis to pelvic lymph nodes.

Conclusion: Preoperative MRI staging may play a role in prediction of micrometastasis (< 1 cm) to pelvic lymph nodes in prostate cancer.

Keywords: MRI; lymph node metastasis; micrometastasis; prostate cancer; tumor staging.