Controlled Surgical Research Trials: Why Are They Important?

You may have seen the recent news that breast cancer recurrences and survival rates were found not to be impacted by the removal of lymph nodes in the armpit. Thanks to a clinical research trial, it was discovered that those women who did not have lymph nodes removed did just as well in the long term as women who did have the surgery to remove them. This good news confirms a very important aspect of modern medicine–that randomized controlled trials (RCTs) are needed to look at results of surgery in the same way they are used to approve new drug treatments.

While randomized controlled trials (RCTs) serve as the basis for a variety of medical treatments, why are the value and safety of surgical procedures infrequently based on RCTs?

Of course, some types of operations are so obviously valuable that no trials are needed. Conversely, some procedures are abandoned because they obviously don't work. But let's look at why RCTs are more difficult when applied to surgical procedures.

Barriers to RCTs in surgery

• Lack of funding: While many medical studies are supported by pharmaceutical companies, drug companies and other commercial firms lack a financial incentive to support surgical trials. Because of this, it is difficult to obtain funding for surgical trials which are unlikely to provide these companies with financial benefits. 

• Learning curve for surgical procedures: Because a number of operations are often required before a surgeon acquires ample skills in the procedure, it is difficult to decide when to start a RCT. The result may be what is referred to as Buxton's law: “It is always too early [for rigorous evaluation] until suddenly it's too late.”

• A procedure is already widely adopted: One example is lapascopic surgery for gallstones. Despite evidence for some complications from this form of surgery, it was in wide use before a RCT could be done.

• Blinding difficulties: This refers to the idea that research trials need to be "blind" to avoid bias (as with drugs being researched, a control group is given a placebo). But how can surgeons and patients fail to know when an incision or other obvious intervention has occurred? This problem is associated with the ethical concerns about “sham” operations which mimic, but do not complete, the full procedure.

• Differing skills and research education among surgeons

• Technical innovations: Surgeons often introduce small “improvements” in an accepted procedure, so it is hard to obtain uniformity in the way an operation is performed by different surgeons.

• Patients and surgeons are unwilling to undergo or perform treatments that vary from widely accepted ones: In some cases the benefits are so obvious that a RCT would be unethical. Some surgeons even believe that all RCTs in surgery are unethical.

• Surgical personality: Surgeons must be decisive and able to make important clinical decisions quickly with incomplete information. Accordingly, they may be uncomfortable with uncertainty about which of several treatments is best.

Yet, surgical trials have led, on the one hand, to abandoning some operations and, on the other hand, to choosing equally effective procedures associated with fewer adverse effects.

Examples of procedures proven ineffective by RCTs

A RCT led to abandoning ligation of the internal mammary artery–one now widely used in coronary artery bypass surgery–to treat angina (with the incorrect belief the procedure would increase blood flow to the coronary arteries).

A RCT evaluation of arthroscopic surgery for osteoarthritis of the knee showed no benefit compared to sham surgery.

Choices of equally effective procedures with fewer side effects

An RTC in 1999 showed that survival and recurrences were the same for the treatment of stomach cancer with removal of local lymph nodes compared with more extensive lymph node excisions which were associated with greater adverse effects.

As mentioned at the start of this blog, the latest example is RTC evidence that survival from and recurrences of breast cancer were not worsened by limiting the removal of lymph nodes in the armpit, a procedure associated with significant long-term side effects.