A new study has expressed concerns over guidelines for American oncologists often recommending expensive and harmful cancer drugs, often based on “weak evidence.”

The research, published in the British Medical Journal looked at drugs recommended for conditions not approved by the US Food and Drug Administration, a process known as “off-label” prescribing. 

Although this a well-known process, commonly used in oncology, it isn’t approved by a regulatory agency. But, recently approved cancer drugs can cost hundreds of thousands of dollars and have severe side-effects. 

“They’re not your grandpa’s old cytoplasmic drugs,” explained Vinay Prasad, an oncologist at the Oregan Health and Sciences University, referring to early cancer drugs. “They are $100,000 drugs. They bring $1bn per year to the drugmakers.”

The lead author added, “It would be one thing if we were talking about drugs that were cheap and have no side-effects.” Many recently approved cancer drugs “have risk-benefit analyses that are just tilted toward benefit. But you can get to a net harm condition.”

The study particularly focused on the US National Comprehensive Cancer Network (NCCN), a body that publishes guidelines developed by oncologists. The recommendations influence treatment decisions and determine which cancer drug insurers are required to pay for. 

In oncology, between 50% and 75% of current prescriptions are off-label, according to some estimates. It is therefore illegal for drugmakers to advertise drugs for off-label uses. 

Prasad’s study looked at 47 new drugs approved by the FDA between 2011 and 2015. The FDA approved these drugs for 69 different indications. However, the NCCN recommended those drugs for 113 indications, 44 more indications than the FDA approved. 

The study concluded that the research “raises concern that the NCCN justifies the coverage of costly, toxic drugs based on weak evidence.”

Such news comes after recent research found 90% of the researchers and physicians who helped develop the NCCN received money from the pharmaceutical industry. 

He concluded, “It is clear with cancer drugs, one has to be very judicious about using them beyond where they’ve been studied.”