Stereotactic radiotherapy for large solitary brain metastases

PURPOSE

To assess effectiveness and toxicity levels of stereotactic radiation therapy without whole brain radiation therapy in patients with solitary brain metastases larger than 3cm.

PATIENTS AND METHODS

Between June 2007 and March 2009, 12 patients received fractionated stereotactic radiation therapy and 24 patients underwent stereotactic radiosurgery. For the fractionated stereotactic radiation therapy group, 3×7.7Gy were delivered to the planning target volume (PTV); median volume and diameter were 29.4 cm(3) and 4.4cm, respectively. For the stereotactic radiosurgery group, 14Gy were delivered to the PTV; median volume and diameter were 15.6 cm(3) and 3.7cm, respectively.

RESULTS

Median follow-up was 218 days. For the fractionated stereotactic radiation therapy group, local control rates were 100% at 360 days and 64% at 720 days; for the stereotactic radiosurgery group, rates were 58% at 360 days and 48% at 720 days (P=0.06). Median survival time was 504 days for the fractionated stereotactic radiation therapy group and 164 days for the stereotactic radiosurgery group (P=0.049). Two cases of grade 2 toxicity were observed in the fractionated stereotactic radiation therapy group, and 6 cases of grade 1-2 toxicity, in the stereotactic radiosurgery group.

CONCLUSIONS

This study provides data to support that fractionated stereotactic radiation therapy without whole brain radiation therapy with a margin dose of 3 fractions of 7.7Gy for treatment of solitary large brain metastases is efficient and well-tolerated. Because of the significant improvement in overall survival, this schedule should be assessed in a randomized trial.

[The influence of age on radiation-induced cognitive deficit:experimental studies on brain irradiation of 30 gy in 10 sessions and 12 hours in the Wistar rat at 1 1/2, 4 and 18 months age]

The objective of this study was to determine the influence of age on the learning and memory dysfunction induced by cranial radiation in the male Wistar rat. Ninety-six 45-day-old, 70 4-month-old, and 78 18-month-old male rats were divided in two equal groups: (i) irradiated and (ii) control. A course of whole-brain radiation therapy (30 Gy in 10 fractions over 12 days) was administered to the irradiated group, while the control group received sham irradiation. Sequential behavioral studies including one and two-way avoidance tests were undertaken before and after the 7 months following radiation. The results suggest that radiation induced progressive and irreversible memory dysfunction in elderly (18-month-old) rats, but this effect was partial or almost reversible in the 4-month-old and 45-day-old rats, respectively. In return, the learning dysfunction was age non-dependent despite the fact that is occurs more rapidly in the young (45 days, 4 months) rats.

Total body 4.5 Gy gamma irradiation-induced early delayed learning and memory dysfunction in the rat

In an attempt to determine the consequences of total body radiation damage on learning and memory in the rat, twenty-eight male Wistar rats aged 4 months received 4.5 Gy total body gamma-irradiation (TBI) while 28 rats received sham irradiation. Sequential behavioral studies of negative reinforcement including a/ one- and b/ two-way avoidance tasks were undertaken. a/ One-way avoidance test: this test was performed before and after TBI. Prior to irradiation both groups were similar. At 20 days (D) and at 3 months post-TBI, irradiated rats had a significantly lower percentage of avoidance than controls but no statistical difference was found at 5 months post-TBI. b/ Two-way avoidance test: this test was performed only after TBI. At days 21, 22, 23, 24, (leaming) and at 4 or 6 months (recalls) post-TBI the mean percentage of avoidance was significantly lower in irradiated than in control rats. This study demonstrates that total-body exposure to 4.5 Gy gamma-irradiation induces behavioral dysfunction affecting learning and transitorily memory. These results suggest that a relatively low dose of total body irradiation can induce neurological complications, which persist 4-6 months later.

Low dose of the gamma acute radiation syndrome (1.5 Gy) does not significantly alter either cognitive behavior or dopaminergic and serotoninergic metabolism

The aim of this study was to evaluate the early-delayed effects of a low dose of the gamma acute radiation syndrome (1.5 Gy) on memory and on dopaminergic and serotoninergic metabolism in Swiss albino CD1 mice, of various ages (6, 10 and 20 weeks). At different times after irradiation (from 24 hr to three months), the mice were trained in a single-trial passive avoidance task and tested for retention either 24 hr or 5 days later. Their performance was compared to that of mice that were sham-irradiated. At the end of the behavioral test (days 3, 9, 30 and 93), the concentrations of dopamine (DA) and serotonin (5HT) and their metabolites were determined in hippocampus, anterior cortex and striatum of mice irradiated at the age of six weeks. No significant behavioral effect was observed whichever the age of the animals or the delay of observation. On the contrary at the moderate dose of 4.5 Gy we observed a significant memory deficit 9 days after the exposure. Considering the neurochemical study, in the striatum or in the frontal cortex, no significant modification was observed whichever the delay or the molecule. In the hippocampus slight modifications were noted: an increase (+144%, p = 0.002) in DA level on day 3 after exposure, and a decrease (-27%, p = 0.028) of 5HT level on day 30 post-irradiation. These modifications were only transient and not associated to modifications of the catabolites. This study demonstrates that total-body exposure to gamma radiation at low dose seems to induce only slight effects on the central nervous system.

[Effect of Ginkgo biloba extract (EGb 761) on rats in an experimental model of acute encephalopathy after total body irradiation]

PURPOSE

To define the therapeutic effect of Ginkgo biloba extract (EGb 761) in an experimental model of acute encephalopathy following total body irradiation in rats.

MATERIAL AND METHODS

Ninety four-month-old rats received 4.5 Gy total body irradiation (TBI) at day 1 while 15 rats received sham irradiation. A behavioural study based on a conditioning test of negative reinforcement, the one-way avoidance test, was performed test, was performed after irradiation. Orally treatment was started one day (study A) or twenty two days (study B) after irradiation and repeated daily for twelve days. In the irradiated group, three subgroups were defined according to the treatment received: EGb 761 (50 mg/kg), EGb 761 (100 mg/kg), water.

RESULTS

This work comprised two consecutive studies. In study A (45 rats) the one-way avoidance test was administered daily from day 7 to day 14. In study B (45 rats) the behavioural test was performed from day 28 to day 35. Study A (three groups of 15 rats): following TBI, irradiated rats treated with water demonstrated a significant delay in a learning the one-way avoidance test in comparison with sham-irradiated rats (P < 0.0002) or irradiated rats treated with EGb 761 (50 mg/kg; P < 0.0017) or EGb 761 (100 mg/kg; P < 0.0002). The irradiated rats, treated with EGb 761 (50 or 100 mg/kg) did not differ from the sham-irradiated controls. Study B (three groups of 15 rats): the irradiated rats, treated with water or EGb 761 (50 or 100 mg/kg) did not differ from the sham-irradiated controls.

CONCLUSION

This study indicates that a relatively low dose of total body irradiation induces a substantial acute learning dysfunction in the rat, which persists fourteen days after TBI. This effect is prevented by the administration of EGb 761 (50 or 100 mg/kg) started twenty-four hours after irradiation.

Anticlastogenic effects of Ginkgo biloba extract (EGb 761) and some of its constituents in irradiated rats

In a previous study we reported that radiation-induced clastogenic factors (CF) are found in the plasma of Chernobyl accident recovery workers and that their chromosome damaging effects are inhibited by antioxidant treatment with a Ginkgo biloba extract (EGb761). In the present study, we induced CF in rats with a radiation dose of 4.5 Gy. The protective effects of the complete extract were compared to those obtained with the extract devoid of its terpene fraction (CP205), with isolated ginkgolides A+B and bilobalide at the concentrations present in EGb761. The pretreatment samples were taken at day 22 postirradiation, the posttreatment samples the day following arrest of the 3-week treatment. The adjusted clastogenic score (ACS) were reduced from 11.71+/-3.55 to 2.00+/-2.83 after treatment with 100 mg/kg and from 13.43+/-2.23 to 4.29+/-2.14 with 50 mg/kg of the complete extract (p<0.0001). Similar protective effects were observed with CP205, ginkgolides and bilobalide (p<0. 001), while the reduction of ACS in placebo-treated rats was not statistically significant (12.80+/-1.79 and 9.20+/-2.68). However, if the efficacy of the treatment was compared to placebo, only the complete extract was significantly protective. While all components exerted anticlastogenic effects at the concentrations present in the complete extract, the comparison of the different groups by analysis of variance did not reveal significant differences. This may be due to to the small number of animals available in each treatment group. The complete extract reduced the ACS by 83% at the dose of 100 mg/kg, while the lower dose of 50 mg/kg and the three components reached only 66%-68% reduction. The better protection provided by the complete extract is due to synergistic rather than to additive effects.

An experimental model of acute encephalopathy after total body irradiation in the rat: effect of liposome-entrapped Cu/Zn superoxide dismutase

PURPOSE

To develop an experimental model of acute encephalopathy following total body irradiation in rats and to define the therapeutic effect of liposome-entrapped Cu/Zn superoxide dismutase.

METHODS AND MATERIALS

A total of 120 4-month-old rats received 4.5 Gy total body irradiation (TBI) while 120 rats received sham irradiation. A behavioral study based on a conditioning test of negative reinforcement, the one-way avoidance test, was performed 5 hours before irradiation and repeated the following days. Subcutaneous treatment was started 1 hour after irradiation and repeated daily for 2 weeks. In both the irradiated and sham group, three subgroups were defined according to the treatment received: liposome-entrapped Cu/Zn superoxide dismutase (0.5 mg/kg), liposomes only, normal saline.

RESULTS

This work comprised two consecutive studies. In study A (90 rats) the one-way avoidance test was administered daily from day 0 to day 4 with a recall session at day 14. In study B (validation phase in 150 rats) the behavioral test was performed only from day 0 to day 6. Before irradiation, all rats showed a similar behavioral response. Study A (6 groups of 15 rats): Following TBI, irradiated rats treated with liposomes only or saline demonstrated a significant delay in learning the one-way avoidance test in comparison with sham-irradiated rats (0.05 < p <0.001 depending upon the day of evaluation and the subgroup type). In contrast, irradiated rats treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from sham-irradiated rats. Study B (6 groups of 25 rats): The results were the same as those in study A, demonstrating a significant delay in the learning of the test in the liposome and saline-treated irradiated rats in comparison with sham-irradiated rats (0.02 < p < 0.001). The irradiated rats, treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from the sham-irradiated controls.

CONCLUSION

This study indicates that a relatively low dose of total body irradiation induces a substantial acute learning dysfunction in the rat. This effect is prevented by the administration of liposome-entrapped Cu/Zn superoxide dismutase.

[Radiotherapy-induced cognitive dysfunction in 4-months-old male Wistar rats]]

PURPOSE

Behavioral dysfunction of memory process arising 4 months after whole brain irradiation (30 Gy/10 fractions/12 days) has been demonstrated in 16-27 month old rats, as compared with non irradiated rats. This study was therefore aimed at delivering the same irradiation in young rats and comparing results with those previously obtained in old rats.

MATERIAL AND METHODS

Thirty-three 4-month old rats were included into the study. Eighteen received whole brain irradiation (30 Gy/10 fractions/12 days), and 18 were given sham irradiation. Sequential behavior studies were done before irradiation and during the 7 months following irradiation.

RESULTS

Significant decrease in memory function was observed in irradiated rats 1 month (p < 0.001), 3 months (p < 0.013), and 6 months (p = 0.007) post-irradiation. This was accompanied by learning deficit 1 month (p = 0.01), 4.5 months (p = 0.03), and 7 months (p = 0.009) post-irradiation.

CONCLUSION

Response to radiation therapy observed in young rats differed from that observed in old rats. Young rats showed earlier decrease in memory function than old rats, but this deficit was followed by partial recovery. Learning deficits also arised earlier in young rats than in old rats. In two cases this deficit was permanent.

Radiation-induced cognitive dysfunction: an experimental model in the old rat

PURPOSE

To develop a model of radiation-induced behavioral dysfunction.

METHODS AND MATERIALS

A course of whole brain radiation therapy (30 Gy/10 fractions/12 days) was administered to 26 Wistar rats ages 16-27 months, while 26 control rats received sham irradiation. Sequential behavioral studies including one-way avoidance, two-way avoidance, and a standard operant conditioning method (press-lever avoidance) were undertaken. In addition, rats were studied in a water maze 7 months postradiation therapy.

RESULTS

Prior to radiation therapy, both groups were similar. No difference was found 1 and 3 months postradiation therapy. At 6-7 months postradiation therapy, irradiated rats had a much lower percentage of avoidance than controls for one-way avoidance (23% vs. 55%, p < or = 0.001) and two-way avoidance (18% vs. 40%, p < or = 0.01). Seven months postradiation therapy the reaction time was increased (press-lever avoidance, 11.20 s vs. 8.43 s, p < or = 0.05) and the percentage of correct response was lower (water maze, 53% vs. 82%) in irradiated rats compared with controls. Pathological examination did not demonstrate abnormalities of the irradiated brains at the light microscopic level.

CONCLUSION

Behavioral dysfunction affecting mainly memory can be demonstrated following conventional radiation therapy in old rats. This model can be used to study the pathogenesis of radiation-induced cognitive changes.

Demonstration of the "anti-stress" activity of an extract of Ginkgo biloba (EGb 761) using a discrimination learning task

1. Young (4-month-old) and old (20-month-old) rats, maintained under water restriction, were trained to discriminate to obtain a small amount of drinking water as a reward. Each animal had to learn to press a lever corresponding to a light that was randomly distributed on the left or right. 2. Introduction of an auditory perturbation ("stress") during the discriminative phase of learning modified the capacity and rate of acquisition in both young and old animals, changes that were correlated with increases in plasma concentrations of epinephrine, norepinephrine and corticosterone. 3. Stress-induced detrimental changes in both discrimination learning and plasma hormones were suppressed by 20 days of oral treatment with an extract of Ginkgo biloba leaves (EGb 761; 50 or 100 mg/kg/day) in both young and old rats, effects that became statistically significant by the third day of learning (time of maximal acquisition rate). 4. EGb 761 treatment was less effective in increasing the percentage of efficient lever presses in old than in young rats, but more effective in decreasing the number of inefficient lever presses and reaction time in the older animals. 5. These results indicate that EGb 761 can facilitate behavioral adaptation despite adverse environmental influences, a property that supports its clinical use in treating cognitive impairment, especially in elderly patients.