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CHICAGO (Reuters) - Medtronic Inc's controversial orthopedic product Infuse, a bioengineered bone-growth protein used in spine surgery, is linked to a greater risk of cancer than previously thought, a prominent researcher said on Thursday.
Infuse was once hailed as a major advance in spine surgery and is now the subject of investigations by the U.S. Senate and the Department of Justice over omissions of safety problems from its clinical trial data and over off-label use.
Infuse also drew intense public scrutiny after the influential Spine Journal, an Elsevier publication, devoted its entire June issue to examining growth products including the recombinant bone morphogenetic protein-2, or BMP-2, as it is more commonly known.
The Journal noted at the time that surgeons, who were paid tens of millions of dollars by Medtronic, failed to report serious complications from Infuse, including cancer, sterility in men, infections, bone dissolution and worsened back and leg pain. The article said complications occurred in 10 to 50 percent of patients who got the product in 13 Medtronic-funded clinical trials between 2000 and 2010.
Dr. Eugene Carragee, a Stanford University School of Medicine professor and editor-in-chief of the Spine Journal who also authored the June article, said his latest analysis better quantified the link between BMPs and pancreatic, breast and prostate cancers.
It included the low-dose form of Infuse that is on the market, and a high-dose version called Amplify that has been rejected by health regulators.
His findings on BMPs, presented at the annual North American Spine Society meeting in Chicago on Thursday, reflected a 2.5 times greater risk of developing cancer one year after the product was used and a five times greater risk after three years. Carragee says he plans to submit his findings for publication.
"Almost certainly this is cancer promoting and not a carcinogenic," he told Reuters in an interview, noting that exposure to a carcinogen takes many more years to result in disease.
He said Infuse was linked to a cancer diagnosis more often than when the product was not used at all. Amplify was tied to more cancer risk than Infuse.
Carragee said he analyzed pooled data, which has its limitations since they include the different doses of the product and different approaches to using it. The data were made available by the U.S. Food and Drug Administration.
Yet all of the pooled data from Medtronic's BMP trials, which strictly excluded patients who had current or previous malignancies, demonstrated higher rates of cancer.
Earlier this year, the FDA raised concerns about BMPs, refusing to approve Medtronic's application for Amplify after its reviewers had a lengthy debate about the cancer risk.
That decision in March also prompted some doctors to question the safety of the lower-dose Infuse.
Medtronic, the world's largest stand-alone medical technology company with annual sales of $16 billion, said Infuse sales slid some 17 percent after the Spine Journal article. Analysts estimate Infuse generated sales of $750 million to $800 million in fiscal 2011, ended in April.
Infuse, approved by FDA for use in some spinal fusion surgeries and dental procedures, is also used for unapproved purposes, or off-label, at the physician's discretion.
While such use is not illegal, the company is prohibited by law from marketing the product for off-label purposes. A U.S. Department of Justice investigation is underway to determine whether that was the case for Infuse.
Medtronic Chief Executive Omar Ishrak, who took the helm in June, said in an interview on Friday that he would do whatever was necessary to ensure patient safety and maintain the integrity of the 62-year-old company.
"We will take whatever action is required to guarantee that," said Ishrak, who was CEO of General Electric Co'sGE Health Systems before joining Medtronic.
Medtronic spokeswoman Marybeth Thorsgaard declined comment on Carragee's latest findings, referring questions to researchers at Yale University. Medtronic in August hired top researchers, led by Dr. Harlan Krumholz, at Yale to review data on Infuse.
Krumholz was not immediately available for comment.