Table 1.

Clinicopathologic Factors of Patients With Micrometastases and Macrometastases

Factor	Micrometastases (n = 1,872)		Macrometastases (n = 441)		P
	No.	%	No.	%
No. of metastatic nodes					< .001
1	1,308	69.9	163	37.0
2-3	469	25.0	160	36.3
≥ 4	95	5.1	118	26.7
Thickness, mm					< .001
≥ 0.50	6	0.3	11	2.5
0.51-1.00	95	5.1	19	4.3
1.01-2.00	586	31.0	67	15.2
2.01-3.00	450	24.1	76	17.2
3.01-4.00	300	16.0	60	16.6
4.01-6.00	276	14.8	78	17.7
> 6.00	159	8.5	30	29.5
Primary tumor ulceration					< .001
Absent	1,069	57.1	192	43.5
Present	803	42.9	249	56.5
Level of invasion					< .001
II	19	1.0	13	3.0
III	298	15.9	52	11.8
IV	1,353	72.3	262	59.4
V	202	10.8	114	25.9
Age, years					.0109
< 50	893	47.7	182	41.3
50-59	414	22.1	93	21.1
60-69	322	17.2	89	20.2
70-79	202	10.8	58	13.2
≥ 80	41	2.2	19	4.3
Primary site					< .001
Trunk	803	42.9	152	34.5
Head/neck	241	12.9	96	21.8
Upper extremity	314	16.8	65	14.7
Lower extremity	514	27.5	128	29.0
Sex					<.001
Male	1,136	60.7	316	71.7
Female	736	39.3	125	28.3
Mitotic rate, mm2*	1,070		268		<.001
< 1	52	4.9	10	3.7
1-19.99	970	90.7	230	85.8
≥ 20	48	4.5	28	10.5

^*Values for mitotic rate do not equal 1,872 and 441 patients, respectively, for micrometastatic and macrometastatic disease, because of missing data from some contributing institutions.