When federal regulators considered whether to approve the new cancer drug Adcetris (brentuximab vedotin) in 2011, five patients showed up at an advisory committee meeting to talk about the need for the drug.

All of them had their travel expenses paid for by Seattle Genetics, the company that makes the drug. They told compelling stories and when the final vote was taken, it was a slam dunk.

Experts on the committee voted 10-0 to recommend approval.

Speakers who purportedly represent the interests of cancer patients at FDA advisory committee hearings often have provided such personal testimonials about the need for new drugs, according to a new study.

But they also often have financial ties to the companies that make the drug, according to a paper published today in JAMA Internal Medicine.

"The industry has hijacked that microphone," said co-author Vinay Prasad, a cancer specialist and assistant professor of medicine at Oregon Health and Science University's Knight Cancer Institute.

The paper looked at speakers at 49 FDA cancer advisory committee meetings between 2009 and 2014.

A total of 103 public speakers were identified, including 31 (30%) who reported financial associations such as having their travel paid for by the company or being connected with an organization that received financial support from the company.

The analysis comes amid concerns that the FDA has approved too many cancer drugs that are not proven to extend life or improve the quality of life.

A 2014 Milwaukee Journal Sentinel/MedPage Today analysis of 54 new cancer drugs found that over the last decade the FDA allowed 74% of them on the market without such proof.

Instead, the agency approved the drugs based on surrogate measures, such as a tumor shrinking, rather than the gold standard and most reliable measure of cancer research, patients actually surviving longer.

Many of the drugs were costly, averaging about $10,000 a month, and carried serious side effects.

Adcetris, the Seattle Genetics drug, was approved in 2011 to treat two types of lymphoma. The approvals were based on surrogate measures. It still has not been proven to increase overall survival. The drug got on the market under the FDA's accelerated approval program that allows for the use of surrogates and less rigorous testing if the drug treats a serious conditions for which there is an unmet need.

Prasad said he believes the anecdotal presentations by patients can have a powerful impact on advisory committee members who are supposed to make their decision based on the science.

He said the presentations have contributed to the growing number of surrogate approvals.

"It's like a thumb on the scale," he said. "You can't sit in the room and not feel some emotion."

What the committees don't hear are the stories of patients in whom the drugs have not worked or who have suffered a serious side effect, he said.

His study warned that while the speakers provide unique and valuable perspectives, what they say should be weighed in light of the financial conflicts.

"It is a mistake to assume that people who speak at these hearing represent the average patient or express what the average patient wants," Prasad said.

In an email, FDA spokesperson Andrea Fischer said that for most advisory meetings committee members must disclose financial interests but members of the general public are not bound by the same conflict of interest laws.

However, the FDA encourages a transparent process and asks them to state any relevant interests they may have before they speak, Fischer said.

"Before the open public hearing session, the chair of the committee makes an announcement to speakers that they are encouraged to publicly disclose any interests," she said. "The decision to publicly disclose interests and statements made to disclose such interests are at the discretion of the open public hearing speaker."

In an editor's note, JAMA Internal Medicine editor at large, Robert Steinbrook, said it is "understandably challenging" to attract public speakers who do not have vested interests.

"Public speakers represent a nonrepresentative sample of speakers who may be biased toward a favorable view of the drug or medical device that is being discussed," he wrote.