Table 1.

Descriptive characteristics of the two sample sets

VariableStudy 1Study 2Test statistic and significance value
No. patients156198
Age at diagnosis or at SNB, y, mean (range)54.9 (19.9-78.5)52.0 (14.4-88.0)t = 1.87; P = 0.06
Sex, female, n (%)81 (51.9)95 (48.0)χ2 = 0.54; P = 0.46
Sex, male, n (%)75 (48.1)103 (52.0)
Site of tumor, n (%)
    Arm31 (19.9)44 (22.2)χ2 = 4.13; P = 0.25
    Head and neck24 (15.4)17 (8.6)
    Leg50 (32.0)69 (34.9)
    Trunk49 (31.4)68 (34.3)
    Unknown2 (1.3)0 (0.0)
Breslow thickness, mm, median (range)1.9 (0.9-12.0)2.0 (0.7-24.0)Mann-Whitney Z = −0.57; P = 0.57
Mitotic rate, n (%)
    <127 (17.3)22 (11.1)χ2 = 7.33; P = 0.03
    1-676 (48.7)90 (45.5)
    >634 (21.8)68 (34.3)
    Unknown19 (12.2)18 (9.1)
Ulcerated tumors, n (%)40 (25.6)58 (29.3)χ2 = 0.58; P = 0.45
Relapsers, n (%)37 (23.7)63 (31.8)χ2 = 3.48; P = 0.06
Deaths, n (%)21 (13.5)47 (23.7)χ2 = 6.17; P = 0.01
Follow-up time, mo, median (range)49.1 (4.9-94.9)38.4 (0.03-111.7)Mann-Whitney Z = 4.65; P < 0.001