Colorectal cancer and lymph nodes: The obsession with the number 12

Table 1 Minimum lymph node sampling recommended for a correct staging

Under 12 LNs	LNs	At least 12 LNs	LNs	Over 12 LNs	LNs
	n		n		n
Caplin et al[65]	7	Nir et al[18]	12	Swanson et al[57]	13
Maurel et al[66]	8	Norwood et al[19]	12	Wong et al[71]	14
Mekenkamp et al[67]	8	Stocchi et al[41]	12	Tepper et al[72]	14
Yoshimatsu et al[26]	9	Wong et al[46]	12	Wong et al[73]	14
Sarli et al[35]	9	Kukreja et al[50]	12	Chen et al[48]	15
Cianchi et al[68]	9	Nelson et al[51]	12	Mukai et al[74]	15
		Lee et al[58]	12	Goldstein et al[75]	17
		Bilimoria et al[69]	12	Tsai et al[25]	18
		Storli et al[70]	12	Le Voyer et al[27]	20
				Joseph et al[76] 03 (T3)	30
				Joseph et al[76] 03 (T4)	40

LN: Lymph node.

Table 2 What “could interfere” with the lymph node count

Modifiable factors	Surgeons	Pathologist
	Specialization	Lack of training
	Case volume	Lack of time
	Surgical technique	Techniques
	Emergency
	Extension
	Laparoscopy
Unmodifiable factors	Patient related	Disease related
	Advanced age	Tumor site
	Female	Tumor staging
	Obesity	Pre-operative radiotherapy

Table 3 Surgeon’s experience vs lymph nodes harvested

	Surgeon's experience	Statistical analysis	LN harvested (expert vs no expert)
Leung et al[11]	> 15 yr	MA: se independent factor (P < 0.05)	13 vs 11 LN
Valsecchi et al[21]	5 colon/yr	MA: se significant predictor (P = 0.001)	Not specified
Shaw et al[23]	Colorectal surgeon	UA: se P = 0.002	11 vs 9 LN
Stocchi et al[41]	Largest case volume	MA: se independent variable (P = 0.018)	86% vs 83.6% pts with ≥ 12 LN

MA: Multivariate analysis; UA: Univariate analysis; LNs: Lymp nodes; se: Surgeon’s experience.

Table 4 Lymph node sampling in laparoscopic vs open approaches

	Laparoscopy		Open
	Patients	LNs	Patients	LNs
	n	n	n	n
COST[91]	435	12	428	12
Veldkamp et al[92]	627	10	621	10
Guillou et al[93]	526	12	268	13.5
Kang et al[94]	170	17	170	18
Braga et al[95]	134	14.5	134	15.3
Hewett et al[96]	294	13	298	13
Liang et al[97]	135	15.6	134	16
Leung et al[98]	203	11.1	200	12.1
Benhaim et al[99]	235	26.8	296	25.9

Only prospective or prospective randomized trials in over 250 patients. COST: Clinical Outcomes of Surgical Therapy Study Group; LNs: Lymp nodes.