CyberKnife® System Experience: Recurrent Prostate Cancer

Case Study | CYBERKNIFE® TREATMENT DELIVERY SYSTEM

CyberKnife® System Experience:
Recurrent Prostate Cancer

WHAT IS THE CYBERKNIFE SYSTEM:

The CyberKnife System is a non-invasive treatment for cancerous and non-cancerous tumors and other conditions where radiation therapy is indicated. It is used to treat conditions throughout the body, including the prostate, lung, brain, spine, head and neck, liver, pancreas, and kidney, and can be an alternative to surgery or for patients who have inoperable or surgically complex tumors. CyberKnife treatments are typically performed in 1 to 5 sessions. The CyberKnife System has more than two decades of clinical proof and has helped thousands of cancer patients.

WHY WE CHOSE TO TREAT WITH THE CYBERKNIFE SYSTEM:

Epic Care is a multi-specialty practice with five community cancer centers each with its own linac. We have 17 Medical Oncologists and 5 Radiation Oncologists. We needed our ablative platform to have the following features:

Able to treat the entire body
Minimize clinical overlap and cannibalization of our existing linacs
Have marketing cachet and bring in self-referred patients
Technology with regional market distinction
Was not just a linac with added SRS capability

THIS CASE STUDY DEMONSTRATES THE VERSATILITY OF THE CYBERKNIFE® TREATMENT DELIVERY SYSTEM ENABLING TREATMENT TO BE DELIVERED TO COMPLEX AND CHALLENGING CASES.

Patient was originally diagnosed with favorable intermediate risk prostate cancer (cT1c, GS 3+4, PSA 9.7). Imaging work-up demonstrated no evidence of disease outside the prostate. He was treated with definitive Palladium-103 (Pd-103) brachytherapy (125 Gy) and had an initially excellent biochemical response. However, the patient subsequently had a PSA failure several years later and imaging with biopsy confirmed a local recurrence of his prostate cancer.

WHO/WHERE

Gautam Prasad, M.D., Ph.D, Radiation Oncologist Epic Care, Walnut Creek, CA

ABOUT EPIC CARE

Epic Care began as a physician practice in San Leandro, CA and grew into a multi-specialty, multi-site practice which offers outpatient infusion, radiation therapy, lab and diagnostic imaging services, across the San Francisco Bay area.

TECHNOLOGY SOLUTIONS

Accuray CyberKnife® Solution

CHALLENGE

Treat patient originally diagnosed with favorable intermediate risk prostate cancer (cT1c, GS 3+4, PSA 9.7). Imaging work-up demonstrated no evidence of disease outside the prostate.

Figure 1a: CyberKnife treatment plan isodose

Figure 1b: Beam geometry for CyberKnife®

TREATMENT PREPARATION:

In our institution, the pre-treatment process for all patients receiving treatment with the CyberKnife System for prostate cancer includes the implantation of four gold fiducial markers and a rectal hydrogel placed under TRUS guidance. This is done either by the Urologist or Radiation Oncologist. The rectal hydrogel is used to minimize dose to the rectum. Planning MRI prostate and CT sim are performed approximately one week after fiducial and rectal hydrogel placement. Prior to CT sim and prior to every treatment fraction the patient is asked to empty bladder and use a Fleet enema. Patients are positioned for treatment, supine with a knee rest for support.

TREATMENT PLANNING AND DELIVERY:

47 non-coplanar beams using sing InCise™ MLC
34 Gy in 5 fractions prescribed to 57.3% of maximum dose (mean 44 Gy, max 59 Gy)
A modification of Dr. Fuller et al. (2015) protocol1 was used. We were able to create an HDR-like dose distribution to avoid hot spots in the urethra and preferentially irradiate the prostate and the periphery, particularly the gross disease.
With VOLO™ optimization, beam-on time was 24 minutes per fraction

POST-TREATMENT:

Patient reported acute toxicity as expected. One year after treatment, he is still doing well, urinary symptoms have returned to pre-disease state, and he has had persistent PSA response.

REFERENCE:

1. Fuller, D., Wurzer, J., Shirazi, R., Bridge, S., Law, J., & Mardirossian, G. (2015). High-dose-rate stereotactic body radiation therapy for postradiation therapy locally recurrent prostatic carcinoma: Preliminary prostate-specific antigen response, disease-free survival, and toxicity assessment. Practical Radiation Oncology, 5(6), e615-e623. doi: 10.1016/j.prro.2015.04.009

Important Safety Information
Most side effects of radiotherapy, including radiotherapy delivered with Accuray systems, are mild and temporary, often involving fatigue, nausea, and skin irritation. Side effects can be severe, however, leading to pain, alterations in normal body functions (for example, urinary or salivary function), deterioration of quality of life, permanent injury, and even death. Side effects can occur during or shortly after radiation treatment or in the months and years following radiation. The nature and severity of side effects depend on many factors, including the size and location of the treated tumor, the treatment technique (for example, the radiation dose), and the patient’s general medical condition, to name a few. For more details about the side effects of your radiation therapy, and to see if treatment with an Accuray product is right for you, ask your doctor. Accuray Incorporated as a medical device manufacturer cannot and does not recommend specific treatment approaches. Individual results may vary.

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