Rise in Node-Positive Prostate Cancer Incidence in Context of Evolving Use and Extent of Pelvic Lymphadenectomy.

BACKGROUND

The incidence of node-positive prostate cancer has risen and might be partially explained by evolving use of lymphadenectomy at a population level. We assessed trends of node-positive prostate cancer in context of extent of lymphadenectomy among men treated surgically for prostate cancer.

PATIENTS AND METHODS

This was a retrospective study using data from a population-based cancer registry to identify men older than 50 years of age diagnosed with prostate cancer from 2010 to 2015 without distant metastases. We considered extent of node dissection as ordinal (1-4, 5-9, 10-14, 15-19, ≥20) and dichotomous (1-14, ≥15) variables. We fit multivariable models to assess trends in receipt of extended lymphadenectomy and then estimated odds of node-positive cancer on the basis of extent of lymphadenectomy.

RESULTS

We identified 280,156 men diagnosed from 2010 to 2015; 5355 men (1.9%) had positive lymph nodes. Incidence of positive nodes increased from 6.4 to 8.4 cases per 100,000 men from 2010 to 2015 (standardized rate ratio, 1.31; 95% confidence interval [CI], 1.20-1.44). Compared with 2010, prostatectomy patients with high-risk (odds ratio [OR], 1.66; 95% CI, 1.42-1.95) and intermediate-risk tumors (OR, 1.66; 95% CI, 1.47-1.88) were more likely to undergo extended lymphadenectomy in 2015. Among high-risk patients, men with ≥20 nodes removed were 7 times more likely to have positive nodes, versus <5 removed (6.1% for 1-4 vs. 32.4% for ≥20; OR, 7.32; 95% CI, 6.16-8.71). After adjusting for extent of dissection, odds of node-positive disease did not increase between 2010 and 2015 (OR, 1.17; 95% CI, 0.98-1.39) among high-risk patients.

CONCLUSION

Increased incidence of node-positive prostate cancer in the United States is partially explained by more frequent use of extended lymphadenectomy.