An analysis of nine clinical trials - including three unpublished ones - concluded that health policies favoring the much more expensive eye drug Lucentis over Avastin were not supported by current evidence.
The study was published on Monday in The Cochrane Library journal, which is produced by the Cochrane Collaboration, a non-profit group that reviews trial data to assess the value of drugs.
There has been a fierce debate for many years over whether Avastin should be used as a cut-price alternative in patients with wet age-related macular degeneration (wAMD), a leading cause of blindness in the elderly.
Avastin is not licensed for wAMD but it works in a similar way to authorized treatments for the condition - Lucentis, which is marketed by Novartis and Roche, and Eylea, from Bayer and Regeneron Pharmaceuticals.
A number of doctors in the United States and Europe already use Avastin in wAMD on an unapproved basis and some pharmacies provide a service of splitting the cancer medicine into smaller doses for eye injections.
The issue is particularly hot in Europe after French lawmakers voted in July to allow Avastin's use, while Roche and Novartis have faced recent regulatory scrutiny in France and Italy on suspicion of anti-competitive practices. The companies have denied any wrongdoing.
In France, Avastin costs about 30 euros ($38.84) per dose, against the 900 euros charged for an injection of Lucentis.
Novartis and Roche have always discouraged the substitution of Avastin for Lucentis, saying that the two drugs were developed for different therapeutic purposes.
A closely watched U.S. government-sponsored study in 2011 concluded that Avastin worked as well as Lucentis in treating vision loss from wAMD but had more adverse side effects.
However, the Cochrane paper found that the safety of Avastin when used in wAMD appeared to be comparable with that of Lucentis, except for a higher rate of gastrointestinal disorders.
David Tovey, editor in chief of the Cochrane Library, said the review addressed a question of "immense importance to health systems in many countries".
The Cochrane researchers noted, however, that their findings were not definitive and that they now plan to conduct a larger review to assess additional sources of evidence.
Novartis said in a statement that Lucentis had a well-known safety profile with more than 2.8 million patient-treatment years of use globally. Avastin's use in the eye, by contrast, has not been systematically reviewed by health authorities.
Roche said it believed that Lucentis is the most appropriate medicine for wAMD, adding that the Cochrane review appears to be based on studies that were not designed to detect differences related to safety aspects.
Lucentis is marketed by Novartis outside the United States and is the company's third-biggest seller, with $2.4 billion in sales last year. Sales of Lucentis for Roche, which markets the treatment in the United States, were $1.9 billion.
(1 US dollar = 0.7725 euro)- Reuters