The importance of non-regional lymph nodes in assigning risk in primary metastatic prostate cancer.

Abstract

227 Background: Patients diagnosed with non-regional lymph nodes (NRLN) in isolation exhibit a more prolonged clinical course than those with bone or visceral metastases in trial data, but evaluation of survival data in general populations is sparse and their presence doesn’t feature in risk estimations based on tumour volume. Methods: The evaluation and prognostic relevance of NRLN metastasis presenting synchronously with osseous or non-ossesous metastasis in hormone-naive prostate cancer was evaluated using the Surveillance, Epidemiology and End-results (SEER) database. Patients with stage M1a-c PCa diagnosed between 2004 and 2009 were identified and included within the analysis. Kaplan Meier was used to estimate overall (OS) and cancer specific survival (CSS) rates in relation to metastatic distribution. Multivariate cox-regression models were used to identify predictors of OS and CSS. Results: Of 4869 metastatic PCa patients identified, osseous metastasis was the most common finding (65.1%); followed by non-osseous (17.5%), osseous + NRLN (7.8%), NRLN (4.9%), non-osseous + osseous (±NRLN) (2.9%) and non-osseous + NRLN (1.8%). Median follow-up was 93 mo. Median OS and CSS were 28 and 34 mo respectively. Patients with osseous + NRLN metastasis had a significantly worse median OS (30 mo vs 25 mo, p = 0.001) and CSS (37 mo vs 29 mo, p < 0.001) compared to osseous only metastasis. On multivariate cox regression, osseous + NRLN metastasis was an independent predictor of OS and CSS when compared to osseous only metastasis (both p-values < 0.01). Conclusions: NRLN metastasis in the presence of osseous metastasis represents a poor prognostic feature when compared to osseous metastasis alone. The current therapeutic stratification of “low vs high volume” disease does not account for this phenomenon and patients requiring aggressive therapy may not receive maximal therapeutic benefit as a consequence.