New prostate cancer treatment: Safer! Easier! Unproven!

One of the thorniest ethical dilemmas in medicine is not who to treat, but how to treat. As new treatments become available for life threatening illnesses, patients and doctors are required to make decisions about whether to stick with the tried and true therapy, and its associated risks and side effects, or switch to the new treatment, which may have fewer risks and side effects, but may be less effective.

Prostate cancer patients already have to make a difficult treatment choice between surgery, radiation and watchful waiting. Surgery and radiation have high cure rates, but both also have high rates of serious complications like impotence and incontinence. That’s because both surgery and radiation inadvertently damage delicate structures like nerves, which are so close by that they cannot be avoided.

A new treatment has recently appeared on the scene, the radiation Cyberknife. Proponents of the radiation Cyberknife claim that it is offers treatment that is far easier (days instead of months) and, because the radiation can be targeted extremely accurately, far less likely to cause serious side effects like impotence and incontinence. Theoretically, it should be just as effective at curing prostate cancer as traditional radiation therapy, but in reality, no one really knows. Hence the ethical dilemma: should the Cyberknife be offered to patients before we have accumulated enough data to be sure that it really works?

I have more than an academic interest in the matter. Eight years ago I chose the Gammaknife for treatment of a benign brain tumor growing within the middle of my brain and pressing on vital structures. Today the Gammaknife is often first line therapy for brain tumors like mine. At the time, though, it was the non-standard alternative, and I might not have even heard of it, let alone chosen it, had I not been a doctor connected with other doctors who were aware of state of the art treatments.

The brain surgeon I consulted strongly recommended surgery even as he counseled that I would lose my hearing on that side and might lose feeling in my face as well. I chose the Gammaknife because the data available at that time suggested that it had an even higher cure rate with a much lower risk of side effects. That turned out to be correct. The new treatment was safer and easier than the old, and was just as effective … fortunately.

Is the Cyberknife a similarly effective alternative to conventional treatment? It has worked very well for tumors of the spinal cord. When it comes to prostate cancer, though, there is far less data available. Indeed, there is less data than the amount of information that was available to me at the time I chose my radiation treatment. Expectations are that, because it is a highly targeted treatment, with the radiation beams “sculpted” to match the exact dimensions of the tumor and spare surrounding tissue, it should be just as effective, and lead to fewer cases of impotence and incontinence. But expectations are just that, expectations, and no one really knows what will happen. Only 2,000 patients have been treated thusfar, and they have been followed for only a few years (not long enough to see long term effects). The preliminary data show that the Cyberknife has a similar cure rate, with fewer short term side effects.

Cyberknife for prostate cancer remains essentially an unproven treatment with great promise. Doctors are struggling with whether it is ethical to introduce such a treatment before it has been proven to be effective. On the other hand, many doctors wonder if it is ethical to withhold such a promising treatment that, theoretically, will reduce the risk of serious and dreaded side effects like impotence and incontinence.

As detailed in a recent Washington Post article, Anthony L. Zietman, president-elect of the American Society for Therapeutic Radiology and Oncology (ASTRO) is opposed to offering the Cyberknife at this point:

“This is really pushing the envelope. It might be as good and more convenient. It may be better and more convenient. But it could turn out to be a disaster. No one knows…”

“We just don’t have the data to support treating prostate cancer with five days of radiation,” said Kevin A. Camphausen of the National Cancer Institute, noting that prostate cancer can recur many years or even decades later. And high-intensity radiation, even though it is more precisely focused, might still damage the rectum, bladder and urethra, potentially causing complications years later.

“What I’m worried about is that we might not be curing patients who we know are curable,” he said.

On the other hand:

Proponents argue that enough evidence has accumulated to make them confident that the approach is at least as good as standard therapies and that it can prevent unnecessary deaths by making treatment less daunting. Because the CyberKnife can more precisely target tumors with higher doses of radiation, it could prove even safer and more effective, they say.

The ethical issues are complicated by the financial incentives. Treating prostate cancer with the Cyberknife represents a tremendous financial boon to the doctors who are advocating its use. They stand to make $1200 per treatment course or more. Cyberknife is faster and more convenient for the doctor as well as the patient. That means that doctors can treat more patients, and make more money, by working the same hours that they worked before. It is not difficult to imagine that this financial advantage could cloud the judgment of Cyberknife proponents.

What does the scientific literature say on this topic? From a discussion of new technologies in radiation therapy:

… While equipment is still developing for the accurate delivery of stereotactic radiosurgery for tumors outside the cranium, many fundamental biological and clinical questions remain regarding the use of these technologies in medical practice…

There is no reason to suppose that all patients or tissue organs will tolerate [treatment] equally well. From the science of radiotherapy, it is understood that toxicities to large radiation fractions are predominantly late occurrences… Since these toxicities may occur late, longer follow-up will be required … [T]here is no reason to suppose that all patients will benefit equally … Only through a consistent and monitored approach will optimal groups be identified for cancer treatment.

In other words, while the new treatment for prostate cancer seems promising, more research is necessary to determine if it is as safe and effective as existing treatments. There is simply not enough scientific research available to guide us. In the meantime, industry is pushing a new and unproven treatment that might be far better than the existing options.

There is only one way to solve this ethical dilemma: the decision must be left to the patient. All options should be presented, and special care should be taken in counseling patients about the unknowns involved in the new treatment. As long as patients realize that they are taking a risk, it is entirely reasonable for them to take that risk in the hope of avoiding serious side effects. This ethical dilemma is similar to many other ethical dilemmas in medicine and the “treatment” is the same: more knowledge and increased patient choice usually represent the best way to move forward.