Endoscopy
Keyhole surgery for colorectal cancer gets go ahead

A 10-year study in Britain has shown that endoscopic surgery to remove colorectal cancer tumours is as effective as conventional open surgery. Middle East Health reports.

Colorectal cancer (CRC) is the second most common cause of cancer death in the United Kingdom and in the United States, where it is second only to lung cancer as the most common cause of cancer-related death.

Patients for whom surgery is considered a good option have traditionally had open surgery where the surgeon removes a section of the intestine around the tumour. However, two studies published recently indicate that keyhole or laparoscopic surgery appears to be as a effective as open surgery.

In the open procedure, surgeons remove a section of the intestine around the tumour through a 20- centimetre cut down the abdomen. This proceudre results in a large scar across the abdomen. In the keyhole procedure, doctors use a tiny camera and long instruments inserted through a fivecentimetre incision, or keyhole, to excise the tumour.

In a 10-year trial by British researchers published in The Lancet Dr Pierre Guillou of St James Hospital in Leeds and his colleagues followed 730 patients with colorectal cancer, including 253 who received open surgery, 484 who received keyhole surgery, and 143 patients who underwent conversion from keyhole to open surgery.

Keyhole surgery has become common in many types of operations but has seen limited use for colon and rectal cancer. Initially there was concern that the tumours would return if open surgery was not performed. In fact, in the mid-1990s, it was shown that the use of keyhole surgery was related to higher rates of tumour recurrence.

Nonetheless, the most recent study builds on previous research by looking at a wider variety of patients, including those who were obese or otherwise not optimal patients for laparoscopic surgery, and patients who had cancer of both the upper (colon) and lower (rectum) parts of the large bowel. In addition, the study relied on surgeons at 27 different medical centres in the United Kingdom, many of whom were not already experts at performing laparoscopic surgery.

Dr Guillou reported that the risk of recurrence and of complications appeared to be about the same for the two types of procedures.

“For cancer of the colon, little difference seems to exist between keyhole surgery and open surgery and there is no reason to expect long-term cancer outcomes to be different. However, impaired short-term outcomes after keyhole surgery for rectal cancer do not yet justify its routine use,” said Dr Guillou.

Dr Myriam Curet, director of the Minimally Invasive Surgery Program at Stanford University Medical Center, California, United States, added: “Keyhole surgery for colon cancer has not been adopted as quickly by the surgical community as other keyhole procedures. In part, the technical challenges of the operation have prolonged the learning curve and minimised enthusiasm. In addition, major concerns about the oncological effects of the operation in patients whose disease has spread have limited its application in colorectal cancer. However, this trial suggests that in appropriately selected patients who are operated on by experienced surgeons, keyhole surgery for colorectal cancer may be the new gold standard.”

Other important findings of the study showed that for patients with rectal cancer, the conventional approach remained slightly better at allowing surgeons to remove the tumour completely. However, laparoscopic surgery was slightly better suited for a more limited type of operation that did not require removal of the entire rectum and anus. While laparoscopic surgery took slightly longer to perform than conventional surgery, patients recovered slightly more quickly and left the hospital sooner. About a quarter of patients with colon cancer needed to have their laparoscopic surgery converted to conventional surgery. For patients with rectal cancer, this number was closer to one-third. On the other hand, the likelihood that surgery was converted from the laparoscopic to the conventional approach decreased over the course of the study, suggesting that surgeons got better at performing laparoscopic surgery as they gained experience.

In another 10-year study published in The New England Journal of Medicine last year, 872 early stage colon cancer patients at US and Canadian hospitals were assessed. It was found that the rates of survival for the two surgical techniques were the same.

Lead researcher Dr Heidi Nelson, of the Mayo Clinic in Rochester, Minnesota, was quoted as saying: "Now we can say it's safe, it's effective and it's beneficial for patients with colon cancer."

Half the patients in the study had keyhole surgery and half had open surgery. Complications, such as wound infections and bleeding, occurred in 21% receiving laparoscopic surgery and in 20% of those undergoing open surgery.

The three-year survival rate was almost the same – 86% for keyhole surgery patients and 85% for open surgery patients. Cancer returned in 16% of keyhole surgery patients compared to 18% of open surgery patients.

The only setback, according to the study was that one in five patients who had received keyhole surgery had to brought back for open surgery because of complications such as the cancer having spread more than was previously thought.

Suitable candidates

Keyhole is not suitable for all colorectal cancers. It is most suited to patients with easily accessible tumours which have not spread to nearby organs.

Furthermore, patients who are treated successfully with keyhole surgery suffer less surgical discomfort, usually have a shorter stay in hospital and make a quicker recovery.

Prevention and detection

Reducing the number of deaths from colorectal cancer depends on detecting and removing precancerous colorectal polyps, as well as detecting and treating the cancer in its early stages. Colorectal cancer can be prevented by removing precancerous polyps or growths, which can be present in the colon for years before invasive cancer develops.

Four tests are recommended for colorectal cancer screening.

- The faecal occult blood test (FOBT), which checks for hidden blood in three consecutive stool samples. One US clinical trial reported a 33% reduction in colorectal cancer deaths and a 20% reduction in colorectal cancer incidence among people offered an annual FOBT. European, populationbased trials have demonstrated that screening every other year reduced colorectal cancer deaths by 15% to 18%.

- In flexible sigmoidoscopy exams, physicians use a flexible, lighted tube (sigmoidoscope) to visually inspect the interior walls of the rectum and part of the colon. Case-control studies found that deaths from colorectal cancers located within reach of the sigmoidoscope were 59% to 79% lower among people who had undergone a sigmoidoscopy than among those who had not had the procedure.

- In colonoscopy exams, physicians use a flexible, lighted tube (colonoscope), which is longer than the sigmoidoscope, to visually inspect the interior walls of the rectum and the entire colon. During this procedure, samples of tissue may be collected for closer examination or polyps may be removed. Colonoscopies can be used as screening tests or as follow-up diagnostic tools when the results of another screening test are positive.

- The double-contrast barium enema test comprises a series of Xrays of the colon and rectum, which are taken after the patient is given an enema containing barium dye followed by an injection of air in the lower bowel.

CT colonography

A separate study has shown that the diagnostic accuracy of CT colonography is excellent in comparison with conventional colonoscopy for colorectal cancer screening. Aashish Goela, MD, a researcher from the University of Western Ontario in Canada, analysed the results of 35 studies that compared the diagnostic accuracy of CT colonography with conventional colonoscopy for detecting average and high-risk patients with polyps or colorectal cancer greater than or equal to 10 mm.

Dr Goela presented his findings at the American Roentgen Ray Society Annual Meeting in May in New Orleans, Louisiana, US.

"The single biggest obstacle to colorectal cancer screening remains patient compliance. CT colonography, which offers similar accuracy to conventional colonography but which is much less invasive, could increase compliance. Colorectal cancer is both highly prevalent and highly lethal, thus any improvement in early detection promises to have a positive impact," said Dr Goela.

"The results of my metaanalysis are very promising and I believe they may even be somewhat conservative. I excluded data in which faecal-tagging, computeraided diagnosis and IV contrast were used as a means to enhance the effectiveness of CT colonography because their roles were unknown when I began collecting data. As these specific components have now been shown to improve accuracy, it can likely be inferred from these results that the accuracy of CT colonography is even higher."

Worms, slugs provide device inspiration

Drawing on an understanding of how slugs, leeches and earthworms traverse their environments and grasp objects, a team of biologists and engineers from Case Western Reserve University in the United States has developed two flexible robotic devices that could make invasive medical procedures such as colonoscopies safer for patients and easier for doctors to administer.

The researchers from Case's departments of biology, mechanical and aerospace engineering and electrical engineering and computer science have obtained a patent for a new endoscopic device and a provisional patent for a gripping device that may have industrial as well as medical uses.

"We have taken our understanding of biology to use it as an inspiration for novel robotic devices," said Hillel Chiel, Case professor of biology and principal investigator on the project. "By taking nature seriously, we have created novel, flexible and adaptive devices that will be useful for a variety of applications." The endoscopic device, constructed of three muscle-like actuators made of latex bladders and surrounded by nylon mesh, looks like a nine-inch long hollow worm.

The actuator segments, inflating and contracting in sequence, propel the device forward, mimicking the undulating movement of slugs and worms. "This device can literally worm its way into complicated places or into curving tubing such as the colon," Prof Chiel explained. The current prototype can be added to existing medical endoscopes. Eventually, the device may be miniaturised and equipped with sensors that enable it to work autonomously and self propelling.

According to Prof Chiel, the research team will also be working to make the device more flexible, imitating the reflex responses of slugs and worms to changes in their environment. As a result of these refinements, the new device could reduce discomfort and the risk of injury among patients undergoing invasive medical tests, and thereby increase compliance with doctors' orders to have such tests performed. Gripper The second device, a biologically inspired "gripper", mimics the way hungry California sea slugs in Prof Chiel's lab grasp seaweed in its many highly slippery forms.

The prototype consists of a four-inch, ball-like device, surrounded by muscle-like actuators in the form of tubes or rings. One of these tubes contains a ‘mouth’ that opens and closes. The ball pushes forward, opens its mouth and grasps at the object before it. This device could meet an industrial need for grippers that can pick up soft objects without destroying them. Building grippers to pick up soft materials has been very hard," Prof Chiel explained.

"Most gripper devices are fairly rigid and designed to work effectively with things that have a fixed orientation or a certain texture or toughness." Prof Chiel also noted that if the gripping device were miniaturised and equipped with sensors, it could have medical applications as well. Such a device, for example, might eat its way through occluded blood vessels.

For nearly two decades and with support from the US National Science Foundation, Prof Chiel has studied the detailed movements of soft-tissue animals such as the California sea slug, chronicling their behavior on film and with MRI imaging. "My focus has been basic science," Prof Chiel explained. "If we can understand how nature controls adaptive behavior through its neural and biomechanical mechanisms, it will have spin-offs in novel devices. But it will also help us understand behavior in more complicated systems like human beings."

                                  
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