Stereotactic Ablative Radiation Therapy (RT) is a modern way of delivering high dose of radiation in a short period of time. Radiation therapy has been given in small doses of daily radiation over a period of 6 to 7 weeks, to give time for the irradiated normal tissue to repair itself between the treatments, to minimize the acute toxicity from RT. SART delivers similar dose of RT in just 3 to 5 treatments.
This is only possible because of the recent improvements in the technology used to deliver the SART. The planning process and the computerized mechanism to shape the RT fields have improved significantly, so a high dose of RT can be delivered to the tumor target volume with a sharp fall off of RT dose to the surrounding normal tissue. Equally important, our machine is able to obtain a 3-D C.T. Scan of the tumor region of the patient just before each treatment, so the radiation can be delivered accurately as planned.
With these advances, high dose RT is delivered with limiting the radiation to the normal surrounding organs. Recent presentation at the 2014 Chicago Multidisciplinary Symposium in Thoracic Oncology reported only about 13% of grade 1-3 side-effects, and no grade 4 or 5 toxicity over 10 years of SART at Cleveland Clinic. SART is a very good option to treat early stage non-small cell lung cancer when surgery is not a plausible option. Although there is no head-to-head comparison of SART to surgical resection in a phase III trial, retrospective studies of SART for lung cancer demonstrated local control of high 80% to low 90% at 2 to 3 years, and low 70% at 5 years, which is comparable to the results of surgical resection.
A prospective phase II clinical trial by The Radiation Therapy Oncology Group, in fact, reported 3 year control in the treated lung tumor of 98%, and control in the treated tumor and involved lung lobe of 91% using SART in medically inoperable patients. Phase III randomized trials comparing SART with surgery in healthy patients who can undergo surgery have been attempted, but they were closed due to poor accrual.
It was difficult to ask patients to allow a study to choose for them to either undergo SART involving 3 to 5 outpatient treatments with expected mild side-effects, versus surgical resection to undergo anesthesia and thoracotomy that result in hospitalization with expected chest wall pain and reduction in pulmonary function. At Houston Precision Cancer Center, we have the modern technology, expertise and extensive experience to use SART to treat patients with early stage lung cancer, hepatocellular carcinoma, oligometastases to the lung, liver, and brain.