Radiosurgery

 Radiosurgery is the application of a high dose of radiation therapy over a few daily sessions (usually five or less) performed in an out-patient setting.

Radiosurgery is defined by the ability to treat with:

  • Higher Radiation Dose per Day
  • Higher Total Effective Dose of Radiation
  • Higher Precision of Treatment
  • Higher Accuracy of Treatment
  • Lower Dose to Critical Normal Structures
  • Lower Number of Total Treatment Days


Radiation Course Rizwan Nurani

Figure depicting radiation dose per day and total length of treatment

All the special techniques described for modern three-dimensional conformal radiotherapy, Intensity modulated radiotherapy, Image guided radiotherapy and motion management are used together to ensure the most precise and accurate delivery of treatment.  The liner accelerator, gantry, multi-leaf collimators, patient table, IGRT positioning system and breathing cycle monitoring system are integrated into one system.  Common systems in use today include Cyberknife ®, Novalis ®, Varian® and Elekta®.    Frequently highly accurate robots are used to move the position of the linear accelerator or the position of the patient lying on the treatment table in order to account for tumor or patient movement.  The individual components of a radiosurgery system are maintained at the highest specifications.

SBRT Lung Tumor Response Rizwan Nurani

Figure Showing (A) An untreated lung Cancer, (B) The radiation dose deposited with Radiosurgery demonstrated in a colorwash overlay, (C)-Early tumor response, (D) Long term tumor control


Due to the confidence in the ability to have a very tightly conformed dose, the confidence that this dose will always be delivered to the target, and the ability to minimize dose delivery to normal structures, higher and more effective dose of radiation can be used in radiosurgery.

Biological Effective Dose Rizwan Nurani

These more effective radiation dose schedules have dramatically improved the ability to control early stage Lung Cancer.  The likelihood that a radiation oncologist will be able to control a primary Stage I Non Small Cell Lung Cancer increases from 30-50% to 90% when radiosurgery is used over traditional methods.  The likelihood of a patient obtaining long term survival rivals that obtainable by traditional surgery.

 RADIOSURGERY STUDIES ON EFFICACY IN LUNG CANCER

Patients with Inoperable Early Stage Lung Cancer

The efficacy of radiosurgery for stage I lung cancer has been widely studied.  Initial studies concentrated on patients who were too sick to tolerate traditional lung resection surgery.  Once these early studies perfected the dose and technique, a landmark prospective multi-center trial was performed through the Radiation Therapy Oncology Group and funded by the National Cancer Institute.  The patients chosen for this study had inoperable Stage I non-small cell lung cancer with tumor size less than five centimeters (two inches).  The results, which were published in the Journal of the American Medical Association (Vol 303, March 2010), demonstrated 91% control of the tumor in the treated lung.

SBRT Lung Metastases LC Rizwan Nurani

These excellent results of greater than 90% local control have also been demonstrated where metastatic cancer has travelled to the lung. In another prospective multi-institutional trial published in the journal of clinical oncology (Vol 27, #10, April 2009) 96% local control rates were obtained.

 

Patients with Operable Early Stage Lung Cancer

These excellent results among inoperable patients have prompted a head to head comparison of surgery to radiosurgery for operable patients with Stage I non-small cell lung cancer.  Multiple trials are underway with the results expected after completion of the studies.

 Prior to availability of this data, there are some international studies that suggest that medically operable lung cancer patients will tolerate and obtain the same level of benefit as medically inoperable patients.  Dr. Onishi published the Japanese experience with lung radiosurgery.  When modern high dose radiosurgery techniques were used, the Local Control achieved was 92%.  More importantly, the long term survival of patients was similar to surgical series with 70% being alive at 5 years.

Operable Lung Ca LC Rizwan Nurani

 A Dutch study published in the International Journal of Radiation Oncology (Vol 83 #1, 2012) identified 177 operable patients within their database of patients treated with Radiosurgery for non-small cell lung cancer.  At the 3-year time point 93% of the cancers were locally controlled.  At 3 years 85% of patients were alive which compares very favorably with operable patients treated with traditional surgery.


Operable Lung Ca OS Rizwan Nurani


© Rizwan Nurani 2012