Table 1.

Baseline characteristics of patients with stage I–II melanoma. n (%) or median (interquartile range). ALM, acral lentiginous melanoma; LMM, lentigo maligna melanoma; NM, nodular melanoma; SLNB, sentinel lymph node biopsy; SSM, superficial spreading melanoma. * According to AJCC 8.

Variable		Sahlgrenska University Hospital n = 367	Erasmus MC Cancer Institute n = 168	Combined n = 535
Gender	Female	181 (49.3%)	80 (47.6%)	261 (48.8%)
	Male	186 (50.7%)	87 (51.8%)	273 (51.0%)
	Unknown	0 (0%)	1 (0.6%)	1 (0.2%)
Age (years)		61 (50–72)	57 (46–67)	60 (48–70)
Breslow depth (mm)		1.80 (1.30, 3.00)	1.90 (1.30, 3.20)	1.80 (1.30, 3.00)
Ulceration	Absent	261 (71.1%)	122 (72.6%)	383 (71.6%)
	Present	106 (28.9%)	39 (23.2%)	145 (27.1%)
	Unknown	0 (0%)	7 (4.2%)	7 (1.3%)
Disease stages *	IA	29 (7.9%)	10 (6.0%)	39 (7.3%)
	IB	156 (42.5%)	70 (41.7%)	226 (42.2%)
	IIA	108 (29.4%)	40 (23.8%)	148 (27.7%)
	IIB	44 (12.0%)	28 (16.7%)	72 (13.5%)
	IIC	30 (8.2%)	13 (7.7%)	43 (8.0%)
	Unknown	0 (0%)	7 (4.2%)	7 (1.3%)
Histologic type	SSM	180 (49.0%)	101 (60.1%)	281 (52.5%)
	NM	138 (37.6%)	50 (29.8%)	188 (35.1%)
	LMM	5 (1.4%)	1 (0.6%)	6 (1.1%)
	ALM	4 (1.1%)	3 (1.8%)	7 (1.3%)
	Other	40 (10.9%)	9 (5.4%)	49 (9.2%)
	Unknown	0 (0%)	4 (2.4%)	4 (0.7%)
Biopsy location	Head/Neck	0 (0%)	1 (0.6%)	1 (0.2%)
	Trunk	176 (48.0%)	80 (47.6%)	256 (47.9%)
	Upper extremities	80 (21.8%)	30 (17.9%)	110 (20.6%)
	Lower extremities	111 (30.2%)	56 (33.3%)	167 (31.2%)
	Unknown	0 (0%)	1 (0.6%)	1 (0.2%)
Clark level	II	17 (4.6%)	9 (5.4%)	26 (4.9%)
	III	169 (46.0%)	46 (27.4%)	215 (40.2%)
	IV	156 (42.5%)	58 (34.5%)	214 (40%)
	V	12 (3.3%)	6 (3.6%)	18 (3.4%)
	Unknown	13 (3.5%)	49 (29.2%)	62 (11.6%)
Angiolymphatic Invasion	Absent	0 (0%)	58 (34.5%)	58 (10.8%)
	Present	0 (0%)	6 (3.6%)	6 (1.1%)
	Unknown	367 (100%)	104 (61.9%)	471 (88.0%)