Table 1.

Patient, tumor, and treatment-specific factors according to treatment era

Variable	Era I: 1988–1999 (n = 1,631)	Era II: 2000–2006 (n = 5,237)	P value
Age, years
≤56	910	2,592	<0.001
>56	721	2,645
Sex
Male	1,045	3,324	=0.66
Female	586	1,913
Breslow depth, mm
0	38	109	<0.001
≤1	233	897
1.01–2	299	1,261
2.01–4	411	1,327
>4	315	1,072
Unknown	335	571
Ulceration
Absent	1,378	3,682	<0.001
Present	253	1555
Number of lymph node metastases
1	886	3,225	<0.001
2–3	377	1,355
≥4	234	532
Unknown	134	125
Surgery
Amputation	2	89	<0.001
Ablation	1	2
Local excision	50	1054
Wide excision (1–2 cm)	427	3,555
Wide excision (>2 cm)	0	264
None	27	246
Unknown	1,124	29