The US Department of Health and Human Services (HHS) recently called into question the safety of a new type of radiation therapy used to treat the asbestos related cancer mesothelioma. Stereotactic Body Radiation Therapy (SBRT) has been used in several patients but HHS opponents are worried that there isn’t enough evidence in the form of empirical studies to definitively say whether or not the treatment was of any use at all.
Mesothelioma is a type of cancer caused by asbestos exposure. The naturally occurring mineral was widely used in the United States from the 1920s to 1985 when the Environmental Protection Agency (EPA) tightened regulations on its use and restricted it from thousands of construction and commercial products.
Airborne fibers can be inhaled or ingested and once in the body they cause a process that leads to the development of tumors. Unfortunately, while many new and experimental treatments, such as Stereotactic Body Radiation Therapy, have been developed to combat the disease, there is still no cure and every case of mesothelioma results in the patient’s death.
Stereotactic Body Radiation Therapy, or SBRT, is a very precise form of radiation therapy that’s able to target individual tumors without inflicting damage on the surrounding parts of the body unaffected by the cancer. The therapy involves delivering exceptionally large doses of either x or gamma ray radiation on target and is differentiated from traditional forms of radiation therapy by its precision.
In 2007 Stanley Benedict (of the University of Virginia) and Kamil Yenice (of the University of Chicago) lead a task force to investigate this new therapy as a viable option for cancer patients. The task force found that fewer stronger doses of radiation delivered better results with fewer side effects than previous types of treatment.
The therapy is actually a hybrid of two existing therapies: stereotactic radiosurgery and intensity-modulated radiation therapy (IMRT) which has, until now, been the most common and most effective radiation therapy for mesothelioma patients.
Stereotactic radiosurgery uses a large number of narrow radiation beams to hit tumors (most often brain tumors) with heavy doses of radiation. IMRT, on the other hand, the beams can be shaped and their intensity modified more accurately deliver a three-dimensional radiation dose which matches the shape and position of the target tumor.
However, Kelley N. Tipton, M.P.H., at ECRI Institute Evidence-based Practice Center, led a group of researchers on a quest to examine this therapy in the light of the results it delivered. The team examined one hundred twenty-four individual cases including information gathered from patients who received SBRT treatments but no other forms of radiation.
The report the team compiled found that “a full systematic review of the current literature cannot answer questions on the effectiveness and safety of SBRT compared to other radiotherapy interventions.” Therefore they recommended further study including “comparative studies … to provide evidence that the theoretical advantages of SBRT over other radiation therapies actually occur in the clinical setting.”
These clinical trials for mesothelioma and non-small cell lung cancers have been tentatively scheduled for 2013.