Determinants of pelvic lymph node dissection during open and minimally invasive radical prostatectomy

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Determinants of pelvic lymph node dissection during open and minimally invasive radical prostatectomy
Background: Controversy exists regarding the importance of pelvic lymph node dissection during radical prostatectomy on cancer control, although lymphadenectomy has been shown to improve staging of prostate cancer. As adoption of laparoscopic and robot-assisted radical prostatectomy continues to grow, it is unclear whether these new technologies are associated with changing trends in performance of pelvic lymphadenectomy. We performed a population study of men undergoing either open or minimally invasive (laparoscopic or robot-assisted laparoscopic) radical prostatectomy to assess factors associated with performance of concomitant pelvic lymph node dissection with each surgical approach.
Methods: Using a 5% national sample of Medicare beneficiaries, we identified 2,702 men who underwent radical prostatectomy between 2003 and 2005. Multivariable logistic regression was used to assess whether surgical approach, surgeon volume, geographic region, patient demographics and patient co-morbidity (Charlson score) were determinants of performing pelvic lymph node dissection.
Results: Men undergoing laparoscopic radical prostatectomy were less likely to undergo concurrent lymph node dissection than those undergoing open surgery (17% v 83%, p<0.001). While surgical volume did not influence the performance of pelvic lymph node dissection during open radical prostatectomy, high-volume minimally invasive surgeons were more likely to perform lymphadenectomy (OR [odds ratio] 1.19, 95% CI [confidence interval] 1.14, 1.25) than their low-volume colleagues. Significant geographic variation existed in performing pelvic lymph node dissection as men in the West (OR 1.61; 95% CI 1.19, 2.17) and the Midwest (OR 1.60; 95% CI 1.22, 2.10) were more likely to undergo lymphadenectomy compared to patients in the South. There was no statistically significant difference in rates of lymph node dissection between men in these regions and those undergoing radical prostatectomy in the East. Older men (>75 vs. 65-69 years, OR 0.23; 95% CI, 0.17, 0.31) and those with multiple comorbidities (OR 0.48; 95% CI 0.35, 0.66) were less likely to undergo pelvic lymph node dissection.

	All		MIRP		ORP
	Odds ratio [OR]	95% confidence interval [CI]	OR	95% CI	OR	95% CI
Surgeon volume (continuous)	1.14	1.10-1.19*	1.19	1.14- 1.25*	1.06	1.00-1.13†
Race (vs. white)
Black	1.20	0.80-1.80	0.95	0.39- 2.31	1.20	0.74-1.92
Other	0.71	0.44-1.17	0.60	0.19- 1.91	0.80	0.45-1.43
Age (vs. 65-69)
70-74	0.65	0.51-0.82*	0.58	0.33- 1.01	0.68	0.52-0.89*
75+	0.23	0.17-0.31*	0.23	0.01-0.54*	0.24	0.17-0.33*
Charlson score (vs. 0)
1 or 2	1.04	0.82-1.31	1.01	0.58-1.73	1.03	0.78-1.35
≥ 3	0.48	0.35-0.66*	2.52	1.15-5.52*	0.39	0.28-0.55*
Region (vs. South)
West	1.61	1.19-2.17*	3.14	1.70-5.81*	1.61	1.13-2.29*
Midwest	1.60	1.22-2.10*	1.57	0.68-3.60	1.37	1.01-1.86*
North	0.84	0.61-1.15	1.35	0.66-2.74	0.74	0.53-1.05
MIRP vs. ORP	0.02	0.02-0.03*
Model Fit	C = 0.84		C = 0.78		C = 0.68

Conclusions: Men undergoing radical prostatectomy utilizing minimally invasive techniques are more than four times less likely to undergo concurrent pelvic lymph node dissection than patients undergoing open radical prostatectomy. This difference was attenuated in surgeries performed by high-volume surgeons performing >48 minimally invasive radical prostatectomies per year. Lymph node dissection was performed less frequently in older men and in those with multiple comorbidities, a finding likely explained by attempts to reduce perioperative morbidity in these patients. Although there were significant geographic differences observed in performance of pelvic lymph node dissection, it remains unclear why these disparities exist. Additional studies are needed to determine the indications and benefits of pelvic lymph node dissection for men with prostate cancer.

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