Medical Device Daily Contributing Writer

SAN FRANCISCO — The American College of Surgeons (Chicago) has more than 74,000 members, with more than 4,000 members from countries outside the US and Canada, making it the largest organization of surgeons in the world.

This widely diverse group met here last week with equally diverse interests, as general surgery is for all practical purposes, becoming a collection of sub-specialties; with workshops, lectures, and courses that supported each specialty topic. Although virtually impossible to cover all subspecialties, those surrounded by excitement included hepatobiliary, bariatric and metabolic, and NOTES surgery.

A surgical subspecialty experiencing an emergence of new therapies is hepatobiliary surgery, with the incidence of liver cancer is growing exponentially in the U.S. and is the most prevalent cancer worldwide, with 500,000 new cases diagnosed annually.

Thought leaders believe that this rise in liver cancer is due to a dramatic rise in incidence of its precursor, hepatitis C, which predisposes certain people to contract the cancer, and is predicted to double in the U.S. over the next five years.

According to the National Cancer Institute (NCI; Bethesda, Maryland), more than 21,000 new cases of liver cancer will be diagnosed in 2008 in the US, with 18,000 patients dying of liver cancer in the same year.

Conventional thinking has been that resection of a hepatoma, or tumor in the liver, is too risky due to the vascularity of the liver. Advancements in technology from four companies have contributed to the development of devices that can cut and coagulate the liver without excess blood loss. These include the Habib device, acquired through the January 2007 acquisition of RITA Medical Systems (RMS; Fremont, California) by AngioDynamics (Queensbury, New York), which delivers bipolar RF energy through a four-needle device, significantly reducing blood loss and allowing the surgeon to perform a non-segmental (just the hepatoma) resection.

AngioDynamics also introduced a new device system called Nanoknife that incorporates irreversible electroporation (IRE), a non-thermal tissue ablation technique in which electrical fields are used to create nano-scale defects in cell membranes, leading to the demise of the cell.

IRE is a physiologic — rather than thermal — change at the cellular level that may have advantages of more precise excision without any damage at all to healthy structures around it. Research is being conducted at select sites in the U.S. using irreversible electroporation for treatment of tumors.

Microsulis' (Denmead, UK) Oncology and Interventional Division has developed a non-thermal method of liver resection with their microwave system for targeted soft tissue ablation that is also being studied in certain centers.

Covidien (Boulder, Colorado) received 510(k) clearance from the FDA last month for microwave ablation use in soft tissue, and is now the first microwave ablation system available globally. Its Evident microwave ablation system is intended for coagulation of soft tissue during percutaneous, laparoscopic and open surgical procedures.

No surgical conference would be complete these days without an update on NOTES surgery. In a post-graduate course on "Minimally Invasive Surgery: The Next Step," Jeffrey Hazey, MD, of the department of surgery at Ohio State University Medical Center (Columbus), presented "Natural Orifice Translumenal Endoscopic Surgery in the Foregut: Translumenal Drainage Techniques, New Diagnostic and Therapeutic Techniques."

He reminded the audience that NOTES is not an entirely new surgical technique; that in fact, percutaneous endoscopic gastrostomy (PEG) and endoscopic cyst-enterostomy procedures have been around for years. "What is new about NOTES is the organ of access," Hazey said, is that "never before have we considered the stomach or vagina as a port of entrance into the abdomen."

He rhetorically asked, "Why are we looking at NOTES?" Because, he said, "it is believed that NOTES may provide a quicker recovery, less immune suppression, better cosmesis, no skin wound infections, the ability for some procedures to be moved into an office setting under local anesthesia, and better viewing of the abdomen. The only major risk is intra-abdominal infections."

If for no other reason but diagnostic, NOTES can be useful for staging cancer, adhesions, procedures for the morbidly obese and evaluation of the abdomen, including trauma. "The views of the abdominal wall are superior to those of laparoscopy," Hazey found in a double blind study where surgeons were asked to evaluate the pancreas and abdominal wall.

The surgeons were divided into two equal groups, one viewing from an endoscope and the other viewing through a laparoscope — each group was unaware of the type of scope they were using.

He told the audience that any NOTES procedure was required to be performed under an IRB, and that in his current ongoing study he was performing gastrotomies only on patients that had to have one anyway.

Hazey said that so far in his research, "open gastrotomy resulted in no clinically significant peritoneal contamination and that it appeared that pre-operative gastric lavage with antibiotics may not be necessary."

According to this summary presentation, it looks as though there may be quite an upside to NOTES procedures in the future.

In the same postgraduate course, Scott Shikora, MD, professor of surgery at Tufts University School of Medicine (Boston), discussed "Emerging Technologies and the Future of Bariatric Surgery."

"There is a large unmet need among the obese for the development of new and novel procedures that might be more appealing than surgery to patients," he said. "Some of these procedures offer new mechanisms of action that do not rely on the traditional caloric restriction or malabsorption that are the mainstay of the current surgical procedures. Others take advantage of the current interest in NOTES and are performed endoscopically instead of trans-abdominally." (See accompanying table.)

There continues to be much debate regarding mechanism of action for the multitude of interventional procedures, some suggestions being: nutrient malabsorption, alteration of gut hormones, dumping of lipids into hindgut, changes in GI nerve function, or reaction to chronic foreign body.

"The dramatic increase in demand has stimulated tremendous interest in developing new technologies and operative procedures," Shikora said. "Although bariatric surgery is entering a new era rich with rapid change and exiting innovations, keep in mind that currently none of these new modalities have been adequately studied to warrant introduction into practice. Some may ultimately be deemed worthy for use while others will likely fail to achieve meaningful results and be abandoned."