Discussions were held Thursday at a national conference of spine surgeons regarding the use of high doses of a Medtronic product during spinal fusion procedures possibly increasing patient’s cancer risks.
The data had been given to the Food and Drug Administration by Fridley-based Medtronic when it tried to receive approval to market a higher strength version of an already existing bone-growth product known as Infuse. Based on those study findings, the FDA rejected that higher dose formula known as Amplify, citing concerns about cancer risks.
During the data presentation at the conference on Thursday, Dr. Eugene J. Carragee of Stanford University stated that not all of the findings of a Medtronic-sponsored clinical trial were made public before. The results of the trial showed a significantly higher number of cancers in the study group receiving Amplify as compared to a control group receiving a bone graft as part of a spinal fusion, he said.
Dr. Carragee also stated that the Amplify study findings had potential implications for patients who received Infuse because both products contained the same active ingredient, a bioengineered bone growth protein known as rhBMP-2.
In a telephone interview with Dr. Carragee, he said that doctors often administered Infuse off-label at levels significantly above the recommended dosages, ones that exceed the amount of rhBMP-2 found in a dose of Amplify.
“This information requires careful consideration because of the large numbers of patients receiving high doses” of Infuse, he said, adding that he was particularly concerned about its use in certain patients like smokers or those with genetic factors that put them at higher risk for cancer.
Dr. Carragee and researchers reviewed the study at a meeting in Chicago of the North American Spine Society, a professional organization. The study showed that three years after the spinal fusion surgery there were 20 cancers in the Amplify group vs. five cases in the bone graft group. Cancers may take years to develop, so date may indicate that the bone growth protein plays a role in promoting cancer rather than actually causing it.
The Spine Journal, edited by Dr. Carragee released a special issue in June challenging earlier published research backing the widespread use of Infuse. The researchers involved in the Medtronic-sponsored studies obviously defended their findings. In response to that publication, Medtronic gave a $2.5 million grant to Yale University in August to conduct an independent review of all study data showing the safety and effectiveness of Infuse. Unfortunately, the results of this report will not be completed until at least next year.
Spinal fusion surgery is a very common procedure thought to be extremely beneficial to patients with serious back issues. Most patients go into this surgery with one known risk; whether or not the fusion will work. Now patients have to worry about another risk, a serious, life threatening risk…bone cancer. Until it is proven with certainty that there is no risk of bone cancer, I would think long and hard about this procedure.