Hyperfractionation decreases the deleterious effects of conventional radiation fractionation on vertebral. Growth in animals

Abstract

Craniospinal axis irradiation in the treatment of pediatric tumors is associated with serious long-term sequelae including decreased bone growth (short sitting stature). In this study, an animal model was used to determine the effects of smaller incremental doses of radiation on bone growth. Sprague-Dawley weanling rats were given 25 Gy to the spine in 8 to 9 days, with fraction sizes ranging from 1.0 to 1.8 Gy. The animals receiving smaller doses per fraction (1.0 or 1.25 Gy) showed significantly more growth of the vertebral bodies in the treated fields than animals given larger incremental doses (1.5 or 1.8 Gy). These findings indicate a protective effect on bone growth for hyperfractionated irradiation of vertebral bodies.

Radioprotection of Osteoblasts by a Fractionated Dose Regimen and Amifostine

“…They concluded that hyperfractionated irradiation of vertebral bodies led to a protective effect on bone growth. 19 Other studies confirm the fact that fractionation is an effective radioprotective strategy for osseous tissue. 20,21 There have been several groups that have addressed the effect of amifostine and a combination of amifostine and fractionated irradiation on bone growth using a variety of animal models.…”

Comparison of the protective effects of melatonin and amifostine on radiation-induced epiphyseal injury

“…Preclinical and clinical studies have demonstrated that epiphyseal growth arrest was reduced to some degree by use of either fractionated or hyperfractionated RT (HFRT) (Eifel 1988, Hartsell et al 1989, Eifel et al 1990, Alheit et al 1998, Damron et al 2000, Damron et al 2001. In Sprague-Dawley rats, HFRT resulted in further epiphyseal protection beyond conventional fractionation (Eifel 1988, Damron et al 2000.…”

Fractionation Effect on Radiation-Induced Growth Retardation of Tibia in Rabbits and Rats

“…Recently, it has been suggested that decreasing the dose per fraction using hyperfractionated radiation schedules may significantly reduce the incidence and severity of radiation damage to growing epiphyses (6)(7)(8). In extensive fractionation studies in weanling rats Eifel et al (7) found an intermediate h/i-value of 4.5 Gy for growth impairment of the tibia.…”