Risk factors for postoperative pathological fractures in lower extremity soft tissue sarcoma patients undergoing limb-sparing surgery

Table 1 Comparison of baseline characteristics between 3D-conformal radiotherapy and intensity-modulated radiotherapy groups, n (%)/median (interquartile range)

Characteristic	3D-CRT (n = 59)	IMRT (n = 71)
Age (years)	56 (45-72)	59 (47-71)
Male	39 (66)	35 (49)
Female	20 (34)	36 (51)
BMI	27.5 (24.7-32.2)	26.4 (24.0-28.3)
Max tumor diameter (cm)	11.0 (5.5-15.0)	9.8 (6.8-15.5)
Tumor size > 10 cm	30 (51)	32 (45)
R1-resection	12 (20)	15 (21)
G3-STS	37 (63)	35 (49)
Periosteal stripping	7 (12)	6 (8)
Bone resection	24 (41)	20 (28)
RT dose (Gy)	60 (50-60)	60 (50-66)
Arterial hypertension	23 (39)	27 (38)
Osteoporosis	0 (0)	4 (6)

BMI: Body mass index; STS: Soft tissue sarcomas; RT: Radiotherapy; IMRT: Intensity-modulated radiotherapy; CRT: Conformal radiotherapy.

Table 2 Multivariate Firth’s penalized Cox regression analysis for risk factors

Characteristic	Hazard ratio	95%CI	P value
Age	1.02	0.99-1.05	0.185
Arterial hypertension	1.99	0.72-5.44	0.166
Radiotherapy	3.16	0.57-17.45	0.116
Bone resection	3.20	1.32-7.77	0.007
Osteoporosis	6.01	1.39-25.94	0.037

Table 3 Multivariate Firth’s penalized Cox regression analysis for risk factors

Characteristic	Hazard ratio	95%CI	P value
Age > 60 years	1.47	1.68-63.00	0.469
Arterial hypertension	2.36	2.32-746.40	0.103
Radiotherapy	3.20	1.78-51719005.04	0.182
Bone resection	3.27	3.83-2857.43	0.009
Osteoporosis	6.28	4.22-803808597164.85	0.014