Purpose
Subclassification of nodal stage may be of prognostic value in men with lymph node metastases (LNM) at the time of radical prostatectomy (RP). We explored the role of extranodal extension (ENE), size of the largest metastatic LN, size of the largest metastasis and LN density (LND) as predictors of biochemical recurrence (BCR).
Materials and Methods
We reviewed pathological material from 261 node-positive prostate cancer patients.
We examined the predictive value when adding the additional pathology findings to a base model including extraprostatic extension (EPE), seminal vesicle invasion (SVI), RP Gleason score, Prostate-Specific Antigen (PSA) and number of positive LNs, using Cox proportional hazards regression and Harrell's c-index.
Results
The median number of LNs removed was 14 (IQR 9, 20) and the median number of positive LNs was 1 (IQR 1, 2). With a median follow-up of 4.6 years (IQR 3.2-6.0 years), 155/261 patients experienced BCR; 5-year BCR-free survival 39% [95% CI 33%, 46%]. The median diameter of the largest metastatic LN was 9 mm (IQR 5, 16). On Cox regression, RP specimen Gleason score (>7 vs. ≤7), number of positive LNs (≥3 vs. 1-2), SVI and PSA were associated with significantly increased risks of BCR. In a subset analysis, size of the metastasis significantly improved the discrimination of the model (Harrell's C 0.700 vs. 0.655 for the base model, p=0.032).
Conclusion
Our study confirms that the number of positive LNs is a predictor of BCR in men with node-positive disease. The improvement in prognostic value of measuring the metastatic focus warrants further investigation.