Table 2 Results of univariate Cox regression analyses

Gender (male vs. female)

0.028

2.17

1.09–4.32

Age (years) (50+ vs. <50)

0.015

2.40

1.18–4.86

Stage of disease (III–IV vs. I-II)

0.005

2.94

1.39–6.21

Tumour size (mm) (100+ vs. <100)

0.437

1.36

0.62–2.99

Tumour weight (gram) (300+ vs. <300)

0.047

2.26

1.01–5.05

Lymphatic metastasis (present vs. absent)

0.001

4.86

1.88–12.54

Distant metastases (present vs. absent)

0.001

4.31

1.45–12.83

Local infiltration (present vs. absent)

0.001

3.20

1.57–6.52

Surgical approach (extraperitoneal vs. transperitoneal)

0.022

0.29

0.10–0.84

Localization (right vs. left)

0.251

1.50

0.75–3.01

Type of surgery (biopsy and tumor reduction vs. adrenalectomy and extended adrenalectomy)

0.191

0.52

0.20–1.38

Reoperation (yes vs. no)

0.550

0.75

0.29–1.95

Surgeons experience (10+ vs. <10)

0.704

0.86

0.40–1.85

Mitotane (used vs. not used)

0.001

0.13

0.06–0.31

Hormonal activity (non-functional vs. functional)

0.544

1.28

0.57–2.86

Symptomatic presentation (yes vs. no)

0.536

0.81

0.41–1.60