New findings about cancer treatment guidelines in the United States have come to light in a published study. The purpose of the study was to determine the differences between recommendations by the National Comprehensive Cancer Network (NCCN) guidelines and the Food and Drug Administration (FDA) approvals of anti-cancer drugs. It also delved into the evidence provided by the NCCN to justify recommendations where differences exist.

The researchers, led by Dr. Vinay Prasad, have found these justifications seem to be based on low-quality evidence or no evidence at all. They believe the research may "raise concern that the NCCN justifies the coverage of costly, toxic cancer drugs based on weak evidence."

Since 1995, the NCCN has published guidelines created by a panel of experts using the best available evidence. But a separate study published in 2016 found 86 percent of the NCCN members involved in creating guidelines had at least one financial connection with the pharmaceutical industry. While 84 percent of them received personal payments, 47 percent got research payments.

Dr. Prasad, of Oregon Health & Science University, explained these user-friendly guidelines are typically used by doctors all over the country to make medical treatment decisions.

"So, we use this for treatment, but the question is... the NCCN may recommend that, but why do they recommend it? What is the evidence supporting those recommendations? In this study, we find unfortunately it is weak or lacking in many cases and I think that is of some concern," he said.

Focusing on the period between 2011 and 2015, the study found a total of 47 new cancer drugs approved by the FDA for 69 indications. However, the NCCN recommended the drugs for 113 indications of which, 69 overlapped with the FDA-approved indications and 44 were additional recommendations. Researchers found only 10 (23 percent) of these additional recommendations were based on evidence from randomized controlled trials, while seven (16 percent) were based on evidence from phase III studies.

In oncology, the common practice of using drugs or combinations that have not been explicitly approved is known as off-label use. 

“It would be one thing if we were talking about drugs that were cheap and have no side-effects,” Dr. Prasad said.

Robert Carlson, the chief executive of the NCCN, said the guidelines rely on the "strongest scientific evidence available." Carlson stressed on the expertise of the panel members who come from 27 leading academic cancer centers in the U.S., which allowed them to "evaluate complex circumstances based on all available data, in order to come to a consensus about what constitutes optimal care."

Though the observational study may be limited with no firm conclusion regarding cause and effect, patients were strongly advised to ask their doctor for existing evidence when seeking treatment. These results, researchers said, "suggest that payers may be covering cancer drugs with varying and scientifically less robust justification."