Cyberknife Radiosurgery Clinical Data for Urologists

As a urologist, seeing and treating prostate, renal and adrenal tumors is part of your routine. Of course, there’s nothing “routine” about it. To add to the challenges, some patients are inoperable and some tumors are marginally resectable or unresectable.

At CyberKnife of Southern California at Vista, we make it possible for you to treat patients and tumors that are inappropriate for invasive surgery. Using the same science that has been successfully treating intracranial tumors since the 1960s, we ablate localized, solid-mass tumors radiosurgically. But while radioablation once required a stereotactic frame, limiting treatment to the cranium, CyberKnife® tracks the tumor’s true location during treatment and continually adjusts for movement. This permits radiosurgical ablation of tumors anywhere in the body, including tumors that are likely to move. Recent studies have shown that CyberKnife has a high rate of success in the treatment of prostate cancer and renal-cell cancers.

CyberKnife differs from radiation therapy, which irradiates both normal and cancerous tissues. CyberKnife delivers an ablative dose to the tumor with submillimeter accuracy and minimal exposure of normal tissue. As a result, we can treat inoperable patients, shrink tumors for less radical resections, destroy radioresistant tumors and treat patients previously treated with radiation. In addition, patients experience short, painless treatments with far fewer side effects, limited (if any) downtime and an immediate return to activities.

CLINICAL INDICATIONS for CyberKnife.

With CyberKnife, the range of tumors treatable with stereotactic radiosurgical ablation is unprecedented. Which urology patients can benefit from this advanced method of tried-and-true radioablation? As the urologic surgeon, that determination rests with you. Here are some of the clinical situations for which CyberKnife may serve as a viable and/or less risky alternative to surgery for prostate, adrenal and renal tumors...

• Localized, solid-mass tumors – While conventional radiation therapy doesn’t do as well in the treatment of these kinds of lesions, CyberKnife’s ablative radiation dose is quite effective in destroying or shrinking them. Although CyberKnife is contraindicated for widespread metastatic disease, it is effective in nonsurgical treatment of certain metastatic tumors or tumors that need to be treated for palliative reasons.

• Medically inoperable patients – Because CyberKnife is noninvasive, it can treat patients who can’t endure surgery or who have a high risk for postoperative complications. With CyberKnife, treatment occurs in one to five short sessions, after which patients can immediately return to their lives. All with far less risk, side effects, recovery period, pain, scarring and hospital stay than surgery.

• Unresectable & marginally resectable tumors – Many localized solid-mass tumors that are not resectable may still be treatable – and effectively – by CyberKnife. The same is true for those that are marginally resectable. CyberKnife often is used alone to treat these lesions but can also be combined with surgery and other treatments to maximize treatment benefit. CyberKnife can also be used preoperatively to reduce tumor volume to make it more easily resected.

• Tumors adjacent to critical structures – CyberKnife’s submillimeter precision means we’re able to destroy or shrink tumors near to or involved with critical structures. In some cases, critical structures may be the reason a tumor is considered unresectable or only marginally resectable. Tumor proximity to critical structures also increases risk of surgical complication. With significantly less irradiation of surrounding tissues, CyberKnife can even treat tumors untreatable with convention radiotherapy because of nearby critical anatomy.

• Prior radiation treatment – With conventional radiation therapy, previous treatment often precludes future radiotherapy. With CyberKnife, however, highdose, short-course, focused treatment is so precise that cumulative exposure is significantly less. Therefore, previous radiation treatment is not a contraindication
for CyberKnife.

• Tumors with high risk of recurrence – For tumor types known to have a high likelihood of recurrence, CyberKnife’s low cumulative exposure makes it an ideal treatment option. If the tumor recurs, the patient can be treated with CyberKnife again (and perhaps multiple times) or be treated with other forms of radiation.

• Radioresistant tumors – It’s true that some tumor types are resistant to the radiobiological effect of conventional radiation therapy. But they aren’t resistant to radiosurgical ablation, which destroys the tumor while preserving surrounding tissue.

• Palliation – While it isn’t indicated for cases of obstructive viscera, CyberKnife can destroy or shrink tumors for reasons of pain relief even if cure is no longer an option.

• Tumors that move – Tumors that move can complicate radiation treatment. CyberKnife tracks the tumor’s true location continually during treatment. The system maintains its extreme precision by responding to any changes in the target’s position or location by repositioning the treatment beam.

Prostate: 

• Robotic radiotherapy for prostate cancer with CyberKnife. Hannoun-Levi et al 2007.  This article, in French, concludes that the CyberKnife System is a technical improvement to existing technology (HDR brachytherapy) for delivering a boost after EBRT.

• Stereotactic body radiotherapy for localized prostate cancer: interim results of a prospective phase II clinical trial. King et al. 2008.   Stanford University Researchers used the CyberKnife System to treat 41 low-risk prostate cancer patients.  With a median follow-up of 33 months they found no patient had a PSA failure.  They conclude that the early and late toxicity profile and PSA response for prostate treatment using the CyberKnife System are highly encouraging.

Kidney:

• Initial evaluation of Cyberknife technology for extracorporeal renal tissue ablation. Ponsky et al. 2003. Researchers from the Cleveland Clinic Foundation used the CyberKnife System to treat pig kidneys.  They were able to ablate target tissue while leaving nearby tissue undamaged.