Table 1.

Baseline Patient, Tumor, and Dosimetric Factors

Factor	Fracture (n = 57) Vertebral Segments	No Fracture (n = 353) Vertebral Segments	Fractures
			No.	Total No.	%
Histology
Breast	3	50	3	53	5.66
GI	3	9	3	12	25
Gynecologic	1	3	1	4	25
Kidney	36	191	36	227	15.86
Lung	6	38	6	44	13.64
Melanoma	2	9	2	11	18.18
Myeloma	2	3	2	5	40
Prostate	0	15	0	15	0
Sarcoma	2	5	2	7	28.57
Thyroid	0	17	0	17	0
Other	2	13	2	15	13.33
Spine level
Cervical	5	42	5	47	10.47
Thoracic	26	173	26	199	13.07
Lumbar	26	112	26	138	18.84
Sacrum	0	26	0	26	0
Paraspinal/epidural disease
Present	38	159	38	197	19.29
Absent	19	194	19	213	8.92
Receiving targeted systemic therapy	31	193	31	224	13.84
Receiving bisphosphonate therapy	14	122	14	136	10.29
Prior radiation
Present	7	87	7	94	7.45
Absent	50	266	50	316	15.82
Age, years
Mean	57.48	57.56	57.55
Range	28-87.67	18-90	18-90
Single segment target	43	161	43	204	20.08
Single versus multiple segments within single target volume	14	191	14	205	6.83
Total dose/fraction
8-17 Gy/1 fraction	16	121	16	137	11.68
18-26 Gy/1 fraction	20	52	20	72	27.78
18-26 Gy/2 fractions	6	41	6	47	12.77
18-35 Gy/3 fractions	11	92	11	103	10.68
25-35 Gy/4 fractions	2	4	2	6	33.33
25-35 Gy/5 fractions	2	43	2	45	4.44
Dose/fraction
< 8	4	51	4	55	7.27
8-11	13	101	13	114	11.40
12-19	22	162	22	184	11.96
20-23	6	20	6	26	23.08
≥ 24	12	19	12	31	38.71
Follow-up, months
Median	2.46	13.39	11.53
Range	0.03-43.01	0.53-113.02	0.03-113.02