'Cyberknife' Radiation: Game Changer for Prostate Cancer?

A targeted form of radiotherapy may prove a game changer in the way that some men with prostate cancer are treated, a top expert says.

Stereotactic body radiation, or SBRT, similar to the targeted radiotherapy of Cyberknife and Gamma Knife that revolutionized the treatment of brain cancer, could provide the much needed option for men with localized prostate cancer, Dr. Raquibul Hannan tells Newsmax Health.

“SBRT can change the treatment paradigm of localized prostate cancer by offering men a convenient alternative to the long nine-week course of daily radiation therapy that is the current standard of care. If they see that they can get their radiation therapy over with only five they may be more likely to choose that route,” says Hannan, assistant professor of radiation oncology at the Harold C. Simmons Comprehensive Care Center in Dallas.

Radiotherapy  – including SBRT – is one of several options offered to men with early state (known also as localized) prostate cancer. This means that their cancer is contained within their prostates and that their protein-specific antigen (PSA) and Gleason scores (both indicators of a cancer’s potential aggressiveness) fall within certain parameters.

Hannan’s study – which is the first to publish five-year results from SBRT treatment for prostate cancer – found a 98.6 percent cure rate with the procedure, he says.

"The high cure rate is encouraging when compared to the reported five-year cure rates from other approaches like surgery or conventional radiation, which range between 80 to 90 percent, while the side effects of this treatment are comparable to the other types of treatment," says Hannan, lead author for the study. "What we now have is a more potent and effective form of completely noninvasive treatment for prostate cancer, conveniently completed in five treatments,” he adds.

Men with early stage prostate cancer are offered several options. One is watchful waiting, or close monitoring, which is usually offered more often to men who are elderly and likely to outlive their cancer, Hannan notes.

But the majority of men fall into the category in which treatment is involved, and they are usually offered the following options:

•    Prostatectomy, the surgical removal of the prostate gland;
•    Brachytherapy, in which doctors implant numerous small radioactive seeds into the prostate gland and, once implanted, the seeds release their radioactivity directly into the prostate gland; and
•    Conventional external beam radiation, which, as noted, involves 42 to 45 treatments that are administered over two or more months, five days a week.

During the study, only one patient experienced a recurrence of his cancer in his lymph nodes, which  Hannan believes was a screening failure and the man’s cancer had already spread before his treatment was started. Had it been not for that, the success rate would have been 100 percent, he notes of the research, which recently appeared in the European Journal of Cancer.

Furthermore, although the study found the side effects from conventional radiotherapy and SBRT to be similar, Hannan believes that this can be improved upon.

“The problem is the prostate gland’s proximity to the bladder and the rectum and when you are up against such close proximity to critical structures, you want to minimize the dose of radiation.  Since SBRT gives a higher dose in each treatment and is thereby significantly more potent, there is a chance of higher toxicity and we were concerned about this. However the side effects were similar to conventional radiation and we believe that we can improve upon that, “ Hannan says.

“We are currently investigating the use of a biodegradable gel to insulate the rectum from the prostate during SBRT treatments and we believe that this will further reduce the bowel side effects from this form of radiation,” he adds.

But although Hannan is pleased with SBRT for early stage prostate cancer, he believes that this technology has the potential to help men with more advanced prostate cancer as well.   “The results in early stage prostate cancer have always been good, so we have hit a glass ceiling in improving on that. In higher risk patients, the cure rates are much poorer – 50-to-60 percent, so I think that it is here where the more potent SBRT radiation will make the most difference,” he says.

There is a trial currently going on to evaluate SBRT in these patients that will hopefully be completed in a year, depending on patient enrollment, says Hannan, adding, “We have enrolled many patients already and they are doing well.”