MONDAY, Feb. 16 (HealthDay News) -- Doctors may not always have complete or clear information when they prescribe cancer medications for uses beyond what the drugs have been approved for, a new study finds.

According to the report, published in the Feb. 17 online issue of Annals of Internal Medicine, the online and hard-copy resource used by oncologists and pharmacists, known as the compendia, does not always contain clear or updated information on using medications for "off-label" purposes, such as treating diseases other than those approved by the U.S. Food and Drug Administration.

Doctors and pharmacists often rely on the compendia for off-label dosage information, making it an authoritative source, in some instances, when a question arises about whether insurance will cover a drug for off-label use.

But the researchers found a lack of systematic methods to ensure the compendia information is regularly reviewed or updated.

"Oncologists and pharmacists use the compendia to guide choice of drugs for cancer patients that are not FDA-approved for use in that patient's disease -- an example would be bevacizumab, or Avastin, for brain cancer," the study's lead investigator, Dr. Amy Abernethy, an oncologist at Duke University, said in a news release issued by the school. "Bevacizumab is approved for use in diseases such as colorectal and lung cancer; it is not FDA-approved for brain tumors. But we have evidence that suggests it could be effective in this population, including peer-reviewed studies."

Abernethy's team, from the Duke Comprehensive Cancer Center, also found inconsistencies and confusion in how some commonly used compendia presented information and updated it. Some entries, for example, were more detailed than others, and information was presented in different ways for different drugs.

"Our study found that there are some limitations in the way the compendia are currently presented, and there are opportunities to improve the system," Abernethy said. "Determining how to improve it will be the next step for policymakers."

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