Purpose: Adequate lymph node (LN) retrieval (>12 LN) is increasingly being considered a surgical quality indicator for colorectal cancer. The purpose of this study is to assess LN yield after laparoscopic colorectal cancer resection compared to the open approach and to analyze changes in harvesting over time in our practice.Methods; From 1996-2007, 431 colorectal cancer patients underwent curative laparoscopic resection. During the study periods of 1996-1997, 2002-2003, and 2006-2007, 243 patients undergoing laparoscopic resection for colorectal cancer were studied. They were matched to 260 control patients undergoing conventional surgery identified from our cancer database and matched by age, operation, gender, date of operation and body mass index. Numbers of examined and involved LNs were compared between the two techniques according to location of tumor and year of surgery. Results; A total of 503 patients (303 male) with a mean age of 66.2+/-12.3 years, and a mean body mass index of 26.7+/-7.3 kg/m2 underwent colorectal cancer resection (243 laparoscopically, 260 open resection) during the study period. The overall average number of LNs retrieved per case was 23.9+/-18.3. There was no statistically significant difference in number of LNs retrieved by laparoscopic versus conventional open surgery (24.1+/- 19.3 laparoscopic vs 23.79+/-17.50 for open p=0.4) There were significant difference between involved LNs retrieved laparoscopically and by open technique (2.04+/- 3.6 vs 1.88+/-4.69 P=0.032). Also, There were significant differences between number of LNs retrieved from right colon, left colon and rectum (28.03+/-14.62, 24.48+/-17.59&19.13+/-15.11) respectively (P<0.001).The year of surgery show significant difference in number of involved LNs in laparoscopic cases only between 1996/1997 and 2006/2007 (P=0.003). Conclusion; Laparoscopic resection of colorectal cancer can achieve similar LN retrieval to the open approach. In this era of new technology and refinement of laparoscopic techniques, LN harvest becomes more optimized.

Variable	Overall No (lap/open)	Laparoscopic		Open		P value
		Examined LN	Involved LN	Examined LN	Involved LN	P value Examined LN	p value Involved LN
laparoscopic	243(48.3%)
open	260(51.7%)
Examined LN		24.1±19.3		23.8±17.5		0.97
Involved LN			2.0±3.6		1.8±4.7	0.032
Rt Colon	194 (101/93)	26.2+/12.4	2.1±4.6	28.4±15.6	1.5±2.7	0.2	0.04
Lt Colon	161 (82/79)	25.19±11.9	2.2±4	23.8±19.7	2.3±6.0	0.3	0.4
Rectum	148(60/88)	19.0±11.2	1.7±4.3	19.8±16.1	2.1±5.3	0.4	0.3
1996-1997	125(61/64)	25.0±16.0	2.2±3.2	23.4±16.2	1.9±3.6	0.23	0.29
2002-2003	127(54/73)	20.5±16.5	2.6±5.5	23.8±18.7	1.9±4.8	0.052	0.04
2006-2007	251(128/123)	26.4±17.4	1.7±4.8	23.5±19.8	1.9±1.5	0.13	0.3