The Zen of Cyberknife Radiosurgery and Cashew Chicken
By Nathan Kim, M.D.

I am fairly new to Springfield, but have been here long enough to be a bona-fide Springfield cashew chicken lover. As you all know, cashew chicken is a local favorite that has come a long way since its inception at Leong’s Tea House several decades ago.

In a sense, cashew chicken may be one of the first hybrid, East-Meets-West culinary feats that blend the best of the Western culture with the best of Eastern culture;one of the first true fusion cuisines which couldn’t have been created without both influences.

An analogous fusion marvel also exists in the field of local cancer therapy. When we think of localized cancer therapy, we traditionally think of surgery and radiation therapy, with each modality serving its own useful purpose. In a sense, as far as the East is from the West, is the same difference in radiation and surgical principles.

Radiosurgery is a fusion modality which utilizes the technology, radiobiology, and the anti-cancer properties of ionizing radiation. Applying this technology in a radical way, radiosurgery delivers high doses of radiation to completely ablate tumors in one to 5 treatments. Similar to the principle of the scalpel cutting out the abnormal mass from your body, radiosurgery radically ablates tumors using this noninvasive approach. 

This approach was first defined in the world of neuro-oncology and neurosciences, where stereotactic radiosurgery has become a well-accepted standard of care for patients who meet the eligibility criteria (limited brain metastases, functional disorders, acoustic neuroma, meningioma, pituitary adenoma, AVMs, etc..). 

However, this modality is now being used effectively in patients with extra-cranial solid tumors including early stage lung cancer, oligometastases (limited metastases to lung, and liver), primary liver malignancies, pancreatic cancer, head and neck malignancies, spine and skeletal malignancies, and GU malignancies.

St. John’s Cancer Center has one of the most sophisticated tools available for delivering stereotactic radiosurgery – the CyberKnife system. We have been treating patients with this system now for a little over two years with remarkable success. In this e-update article, I’d like to highlight for you some of the data on where St. John’s Cyberknife radiosurgery center stands today in terms of number of patients and sites treated, the success rate of therapy thus far, and the research initiatives of our group.

Sites Treated

When we look at our past year’s experience, 52 percent of our patients treated involved intracranial sites, which could include brain primary and metastatic neoplasms, as well as functional disorders.  21 percent of our therapies involved thoracic neoplasms, including primary and oligometastatic lesions, followed by spine lesions. These numbers are very much in line with national trends as noted above, with intracranial, lung, and spine being 45 percent, 18 percent, and 13 percent respectively.  We have 0 percent prostate patients treated using CyberKnife radiosurgery compared to national average of 7 percent.. 

Number of patients treated

Over the past year, on the average, our Cyberknife Radiosurgery Center has treated 8+/-2.4 patients per month. This is slightly lower than the national trend of 11.3 +/- 0.5 patients per month treated at most community hospitals across the nation.  This lower trend reflects the fact that we may have room for growth as awareness of this modality continues to increase across the region.

Preliminary Outcome Data: Intracranial pathologies

In collaboration with our research department, the Cyberknife Radiosurgery Center has started to collect outcomes data on some of our patients treated.  When looking at our busiest site, which are the intracranial neoplasms and functional disorders, our data at 1 year looks very promising.  Our one- year survival of patients presenting with brain metastases is 47 percent with a 3 percent major complication rate. 

This data is quite favorable to national trends for patients with the most favorable features, suggesting the effectiveness of our center’s ability to provide quality care for patients with brain metastases.  In our non-malignant intracranial pathologies, our data has thus far been impressive. Our local control rate for meningioma and acoustic neuroma at 1 year stands at 100 percent with 0 percent grade 3 complication rate. Trigeminal neuralgia therapy has been equally successful, with 90 percent of our patients reporting pain relief at one year.  All of these data fair extremely well when compared to national trends, however, we do acknowledge the limitations of this being only a one-year follow-up. Long term data, therefore, will need to be assessed to further validate our results compared to national trends.

Preliminary Outcome Data : Extracranial Pathologies

Our primary extracranial site treated to date has been early stage lung cancer. These are patients who have been carefully selected to have early stage lung cancer, whose performance status or co-morbidities did not permit them to under surgery, and therefore were treated with Cyberknife Body Radiosurgery. Few of them were patients with recurrent diseases. When we look at our one-year local control in patients treated with doses in the range of 4200-6400 cGy in 3-4 fractions (12 to 20 Gy/fraction), these patients had 100% radiographic local control with 0 percent complication rate at six months. Comparison to national trends is not yet feasible due to the short follow-up period for our lung cancer patients, but thus far our results are quite promising.

National Recognition

Our Cyberknife Radiosurgery Center has achieved national recognition on several fronts.  In the past Cyberknife Annual Users Meeting held January of 2007, our center was selected for three oral presentations, and one poster discussion section (Dr. Nathan Kim, Dr. Alan Scarrow,  Eddie Spain, and Carla Hunt) highlighting our research efforts, and one of our staff was selected to be a moderator of the Neuroscience oral presentation section (Dr. Scarrow). 

Most recently, our center was awarded a one-year research grant from the Cyberknife Society to determine better methods of interpreting PET results of lung cancer patients treated with radiosurgery. We are hoping that this research will provide a more easily interpretable quantitative method for measuring tumor metabolic activity and likelihood of disease recurrence. This was a meritorious grant awarded through a competitive process, and this award further affirms St. John’s Radiosurgery Center’s national prominence in the field of radiosurgery.

Summary

Radiosurgery is a highly effective non-invasive modality which blends the oncologic principles of surgery and radiation medicine to maximize benefit to appropriately selected patients with often times a devastating malignancy. Radiosurgery will  continue to impact our community and this modality is here to stay.  The role for radiosurgery is anticipated to continue to increase, with continued technological advancement, and with published research being produced which will gain further support for the unprecedented effectiveness of this modality to deliver tumoricidal therapy in a safe and non-invasive manner.  Please visit our Web site or call us at 417-820-9365 or 1-877-560-4100
to see if Cyberknife radiosurgery may be an option for your patients or loved ones.