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May 12, 2005
Role of pentoxifylline and vitamin E in attenuation of radiation-induced fibrosis.
Topics: MedicineHere is a topic of great interest to many patients that have received radiation therapy as treatment for cancer, particularly patients that have suffered from head and neck cancer. Radiation-induced fibrosis, although relatively rare, can be extremely painful and disabilitating.
The following abstract review focuses on a study to evaluate the use of pentoxifylline and vitamin E as monotherapy and
in combination for the treatment of radiation-induced fibrosis (RIF).
Background
Radiation-induced fibrosis (RIF) is a rare morbid complication of radiotherapy, without a proven and established method of management. The treatment of malignant tumors by radiation therapy is limited by the need to avoid excessive late damage to normal tissues. Although new strategies designed to improve the therapeutic ratio have reduced the incidence of radiation-induced fibrosis (RIF), it is still sometimes severe and unavoidable, and slight differences exist in its clinical presentation. Like fibrotic sequelae of any origin, RIF is mainly characterized by nonspecific changes in the connective tissue involving excessive extracellular matrix deposition and hyperactive fibroblasts. Functionally, RIF is reflected in loss of range of motion and muscle strength and the development of limb edema and pain. Tumor necrosis
factor alpha and fibroblast growth factor 2 (FGF2), which are abnormally elevated in irradiated tissues, may mediate radiation fibrovascular injury. Patients treated with pentoxifylline have demonstrated improved Active and passive range of motion, and
muscle strength and decreased limb edema and pain. Reversal of these
delayed radiation effects was associated with a decrease in circulating
FGF2.
Data Sources
Literature retrieval was performed through MEDLINE
(1966-March 2004) using the terms vitamin E, alpha-tocopherol,
pentoxifylline, radiation-induced fibrosis, and radiation injury.
Data Synthesis
Few treatments exist for managing RIF of soft tissues. Due
to its antioxidant properties, vitamin E may reduce the oxidative
damage induced by radiation. The precise mechanism of action for
pentoxifylline in management of RIF remains unclear. Uncontrolled
studies evaluating vitamin E or pentoxifylline as monotherapy in RIF
have shown modest improvement in clinical regression of fibrosis.
However, controlled data are needed to verify these benefits. Studies
involving pentoxifylline plus vitamin E demonstrated regression in RIF.
The combination was more effective than placebo and may be superior to
monotherapy with either agent. Adverse effects were rarely reported in
the studies and consisted mainly of gastrointestinal and nervous system
effects.
Conclusions
Overall, pentoxifylline is well tolerated and is
one of the few commercially available drugs with clinical data for
management of RIF. Despite a lack of large, well-designed clinical
trials, pentoxifylline plus vitamin E should be considered as an option
in patients with symptomatic RIF.
Question of the day - could circulating FGF2 offer a potential target as a mechanism for amelioration or elimination of radiation-induced fibrosis? It's
Related readings
The human FGF2 level is influenced by genetic predisposition.
Improving surgical wound healing with basic fibroblast growth factor after radiation.
Pentoxifylline in the treatment of radiation-induced fibrosis.
Treatment of radiation-induced fibrosis of the face with manual compression therapy
Striking regression of radiation-induced fibrosis by a combination of pentoxifylline and tocopherol
Posted by Hyscience at May 12, 2005 10:20 PM
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