Radiotherapy for neovascular age-related macular degeneration.

BACKGROUND: Radiotherapy has been proposed as a treatment to prevent new vessel growth in people with neovascular age-related macular degeneration (AMD). OBJECTIVES: The aim of this review was to examine the effects of radiotherapy on neovascular AMD. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group trials register) on The Cochrane Library Issue 2, 2004, MEDLINE (1966 to May 2004), EMBASE (1980 to June 2004) and LILACS (Latin American and Caribbean Health Sciences Literature Database) (May 2004). We also wrote to investigators of trials included in the review to ask if they were aware of any other studies. SELECTION CRITERIA: We included all randomised controlled trials in which radiotherapy was compared to another treatment, sham treatment, low dosage irradiation or no treatment in people with subfoveal choroidal neovascularisation secondary to AMD. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted the data. Relative risks were combined using a random effects model. The percentage of the variability in effect estimates that was due to heterogeneity, rather than sampling error, was estimated using I2. MAIN RESULTS: Eleven trials randomising a total of 1078 people were included in this review. All trials used a similar method of delivering the radiotherapy treatment (external beam). Dosage ranged from 7.5 to 24 Gy. Most trials found effects (not always significant) that favoured treatment. However, there was considerable inconsistency in the results between trials (I2 > 50%). As only 11 trials were included in the review and only some of these trials provided data for each outcome our ability to determine the causes of the heterogeneity between trials was limited. Subgroup analyses did not reveal any statistically significant interactions although with small numbers of trials in each subgroup (range two to four) this was not surprising. There was some indication that trials with no sham irradiation reported a greater effect of treatment as did trials with a greater percentage of participants with classic choroidal neovascularisation. REVIEWERS' CONCLUSIONS: This review currently does not provide evidence that external beam radiotherapy is an effective treatment for neovascular AMD. If further trials are to be considered to evaluate radiotherapy in AMD then adequate masking of the control group must be considered. Given the recent evidence that most lesions are amenable to treatment with photodynamic therapy if identified at a small lesion size, trials evaluating radiotherapy against photodynamic therapy are warranted.