WEDNESDAY, June 1 (HealthDay News) -- Undergoing an operation can be scary, but University of Michigan researchers offer some reassuring news: Deaths among those having high-risk surgery have fallen substantially in recent years.

Much of this is due to many high-risk cancer operations being done in hospitals that do a lot of them and to overall better compliance with safety guidelines, the researchers noted.

"Overall, surgery in the United States is getting safer," said lead researcher Dr. Jonathan F. Finks, an assistant professor of surgery at University of Michigan Health Systems. "However, there is still room for improvement. Our focus should be on strategies that improve outcomes across all procedures."

The report is published in the June 2 issue of the New England Journal of Medicine.

For the study, Finks and colleagues used Medicare data to look at cancer and cardiac surgeries among an older population between 1999 and 2008.

"With complex cancer operations, operative mortality declined between 11 percent for resection of esophageal cancer and 19 percent for resection of pancreas cancer," Finks said. "With major cardiovascular surgery, mortality declined between 8 percent for carotid endarterectomy [removal of plaque] and 36 percent for repair of abdominal aortic aneurysm."

With cancer surgery in particular, mortality has dropped in large part because more patients are having their surgery in safer, high-volume hospitals, Finks explained. "For many high-risk procedures, hundreds of lower volume hospitals in the U.S. have stopped doing them," he explained.

However, the reasons for declining deaths with cardiovascular surgery remain uncertain, Finks said. "Possible reasons include use of minimally invasive techniques in the repair of abdominal aortic aneurysms," he added.

Other improvements include the development of large national registries and quality improvement initiatives from surgical societies, as well as public reporting initiatives and regional quality improvement groups, Finks said.

"Finally, in the wake of the 1999 Institute of Medicine report on preventable medical errors, hospitals and surgeons have placed increasing emphasis on optimizing patient safety," he said.

However, although deaths during complex surgery have dropped, outcomes still vary across hospitals, Finks added.

"For a small number of complex cancer operations, referral to a high-volume hospital should continue to be encouraged. With most complex operations, however, other quality improvement strategies are likely to be more effective than simple referral to a high-volume center," he said.

Dr. Tomas Salerno, chief of the division of cardiothoracic surgery at the University of Miami Miller School of Medicine, said that "this issue of volume and risk of surgery is something that has been debated for quite awhile."

It does seem to make sense that hospitals that do more of a given procedure do it better, he said. "This applies to a lot of procedures," Salerno said. However, it doesn't seem to apply to heart bypass surgery, he added. The reasons for this aren't clear, Salerno said.

"But whether this applies for other complex procedures is not answered by this study. So, if you are going to have a major procedure it may be better done in larger centers," he said.

Salerno said he thinks the patient-doctor relationship is probably as important in selecting where you want a procedure done.

More information

For more on patient safety, visit the U.S. National Library of Medicine.