The Cyberknife System: On Par with Increasing Cancer Patients’ Survival Rates When Compared to Other Treatment Techniques

Ariana Gopal

Three of the primary methods for killing off cancerous cells in a person’s body are chemotherapy, surgery, and various forms of radiation therapy.  Chemotherapy targets all rapidly producing cells in a person’s body and is generally prescribed in the form of a drug; it is often used in cases where an individual’s cancer has spread (also known as metastasis).  In contrast, surgery and radiation therapy are more specifically targeted toward cancerous lesions in a localized region of the body.  Surgical procedures are invasive and are geared toward physically cutting out cancerous masses.  Radiation therapy uses radiation waves to specifically target cancer cells.  In comparison to chemotherapy, radiation therapy is localized and noninvasive, essentially making it less toxic to the body.  In comparison to surgery, radiation therapy will not put patients in remission for extended periods of time.  With advancements in radiosurgery, like the Cyberknife, radiation therapy is becoming more precise and offering patients the treatment they need for their cancer in fewer treatments.

The goal of this research was to explore the impact of Cyberknife treatment on patients with cancer outside of the nervous system, as well as to compare the effectiveness of radiosurgery versus other typical treatment methods.  Two of the articles specifically focused on hepatocellular carcinoma, a type of cancer that effects the liver.  One traced survival rates 1-3 years after patients received surgery; survival rates were 88.5%, 73.1%, and 69.2% for traditional surgery, whereas those for the Cyberknife were 72.7%, 66.7%, and 57.1% (Zhuang et al., 2013).  This article indicated that traditional surgery prolonged the survival of patients with hepatocellular carcinoma over Cyberknife surgery, although these results were not considered significant (Zhuang et al., 2013).  The article evaluating different treatments on hepatocellular carcinoma focused on external beam radiation therapy in comparison to chemoembolization and resection techniques.  In contrast to the previous article, the median survival rate and 1-year survival rates were 8 months and 34.8% in the radiation group, and 4 months and 11.4% in the non-radiation group, indicative that radiation therapy had a better impact on improving the survival rates of patients with hepatocellular carcinoma over other treatment techniques (Zeng et al., 2005).  In a study comparing Cyberknife radiosurgery to traditional surgery for a type of lung cancer, patients receiving Cyberknife had a 95% overall survival rate after 3 years, in comparison to 80% in the surgery group (Chang et al., 2015).  A study exploring radiosurgery and traditional surgery indicated that both had an average 1-year survival rate of 60% for patients with brain tumors (O’Neill et al., 2003).  Although both groups had similar survival rates, the chance of recurrence was significantly less for the radiosurgery group (O’Neill et al., 2003).  Similar survival rates were also noted in a study comparing radiosurgery to more traditional radiation therapy, reporting 91% and 88% 6-year survival rates, respectively, for patients being treated for prostate cancer (Ricco et al., 2016).

As indicated by the studies above, there are clearly mixed results when comparing radiosurgery techniques like the Cyberknife system to other treatment methods, predominantly traditional surgery.  One of the studies indicated that the system was worse than other techniques, two had very similar survival rates, and those that showed a higher survival rate for patients treated with the Cyberknife system did not report statistical significance.  Overall, it appears that the Cyberknife system is on par with other techniques, surgery in particular, when it comes to treating various types of cancer.  In the future, it could be helpful to specifically focus on the effects of the Cyberknife system on one specific type of cancer.  Focusing this way can make it clearer whether or not the Cyberknife system is an effective way of treating a specific kind of cancer.  Additionally, the cost-effect ratio for this system can also be explored in future research.

Figure 1 Shows a three-dimensional image created by the Cyberknife system with the different angles at which radiosurgical waves will be hitting the target location. This picture depicts the Cyberknife targeting the liver. (Protocol, n.d.)

References

Chang, J. Y., Senan, S., Paul, M. A., Mehran, R. J., Louie, A. V., Balter, P., Roth, J. A. (2015). Stereotactic ablative radiotherapy versus lobectomy for operable stage I non small-cell lung cancer: A pooled analysis of two randomised trials. The Lancet Oncology, 16(6), 630-637.

O’Neill, B. P., Iturria, N. J., Link, M. J., Pollock, B. E., Ballman, K. V., & O’Fallon, J. R. (2003). A comparison of surgical resection and stereotactic radiosurgery in the treatment of solitary brain metastases. International Journal of Radiation Oncology*Biology*Physics, 55(5), 1169-1176.

Protocol for Cyberknife Treatment of Limited Liver Metastases. (n.d.).

Ricco, A., Manahan, G., Lanciano, R., Hanlon, A., Yang, J., Arrigo, S., Brady, L. (2016). The Comparison of Stereotactic Body Radiation Therapy and Intensity-Modulated Radiation Therapy for Prostate Cancer by NCCN Risk Groups. Frontiers in Oncology, 6.       

Zeng, Z., Fan, J., Tang, Z., Zhou, J., Qin, L., Wang, J., Wang, Y. (2005). A comparison of treatment combinations with and without radiotherapy for hepatocellular carcinoma with  portal vein and/or inferior vena cava tumor thrombus. International Journal of Radiation Oncology*Biology*Physics, 61(2), 432-443.

Zhuang, H., Pang, Q., Song, Y., Yuan, Z., Tian, L., & Dong, Y. (2013). Comparative research on the efficacy of CyberKnife® and surgical excision for Stage I hepatocellular carcinoma. OncoTargets and Therapy, 1527-1532.