Stereotactic Radiation Therapy: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT)

Jurisdiction: J6 MAC Part B. States: Illinois, Minnesota, Wisconsin. Type: Active LCD

Abstract: Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) are methods of delivering ionizing radiation using highly focused convergent beams to target a lesion while limiting exposure of adjacent structures. “Stereotactic” describes target lesion localization relative to a known three dimensional reference system that allows for a high degree of anatomic accuracy and precision. Devices used for stereotactic guidance may include a body frame with external reference markers in which a patient is positioned securely, a system of implanted fiducial markers that can be visualized with low-energy (kV) x-rays, and CT-imaging-based systems used to confirm the location of a tumor immediately prior to treatment. SBRT is used to treat extra-cranial sites as opposed to stereotactic radiosurgery (SRS) which is used to treat intra-cranial and spinal targets. Treatment of extra-cranial sites excluding the spinal cord and related spinal structures requires accounting for internal organ motion as well as for patient motion. Thus, reliable immobilization or repositioning systems must often be combined with devices capable of decreasing organ motion or accounting for organ motion e.g. respiratory gating. Additionally, all SBRT is performed with at least one form of image guidance to confirm proper patient positioning and tumor localization prior to delivery of each fraction. SBRT is only indicated as primary treatment for tumor types or locations where the available published literature supports an outcome advantage over other conventional radiation modalities. SBRT may be delivered in one to five sessions (fractions). Each fraction requires an identical degree of precision, localization and image guidance. SRS is typically performed in a single session, using a rigidly attached stereotactic guiding device, other immobilization technology and/or a stereotactic-guidance system. The higher a Karnofsky Performance Status, the better a patient is doing. The lower an Eastern Cooperative Oncology Group (ECOG) Performance Status is, the better a patient is doing. This is the opposite of the Karnofsky Performance scores where a lower score reflects a poorer status. SRS/SBRT procedures include the following components: Planning Position stabilization (attachment of a frame or frameless) Imaging for localization (CT, MRI, angiography, PET, etc.) Computer assisted tumor localization (i.e. “Image Guidance”) Treatment planning – number of isocenters, number, placement and length of arcs or angles, number of beams, beam size and weight, etc. Isodose distributions, dosage prescription and calculation Setup and accuracy verification testing Simulation of prescribed arcs or fixed portals Radiation treatment delivery Indications for SRS/SBRT (for Cranial and Spinal Lesions): Primary central nervous system malignancies, generally used as a boost or salvage therapy for lesions Primary and secondary tumors involving the brain or spine parenchyma, meninges/dura, or immediately adjacent bony structures. Benign brain tumors and spinal tumors such as meningiomas, acoustic neuromas, other schwannomas, pituitary adenomas, pineocytomas, craniopharyngiomas, glomus tumors, hemangioblastomas. Cranial arteriovenous malformations, cavernous malformations, and hemangiomas Other cranial non-neoplastic conditions such as trigeminal neuralgia and select cases of medically refractory epilepsy. As a boost treatment for larger cranial or spinal lesions that have been treated initially with external beam radiation therapy or surgery (e.g. sarcomas, chondrosarcomas, chordomas, and nasopharyngeal or paranasal sinus malignancies). Metastatic brain or spine lesions, with stable systemic disease, Karnofsky Performance Status 40 or greater (or expected to return to 70 or greater with treatment), and otherwise reasonable survival expectations, OR an Eastern Cooperative Oncology Group (ECOG) Performance Status of 3 or less (or expected to return to 2 or less with treatment). Note that the higher a Karnofsky Performance Status is, the better a patient is doing. However, the lower an Eastern Cooperative Oncology Group (ECOG) Performance Status is, the better a patient is doing. Relapse in a previously irradiated cranial or spinal field where the additional stereotactic precision is required to avoid unacceptable vital tissue radiation. Choroidal and other ocular melanomas Limitations for SRS/SBRT (for Cranial and Spinal Lesions): SRS is not considered medically necessary under the following circumstances: Treatment for anything other than a severe symptom or serious threat to life or critical functions. Treatment unlikely to result in functional improvement or clinically meaningful disease stabilization, not otherwise achievable. Patients with wide-spread cerebral or extra-cranial metastases with limited life expectancy unlikely to gain clinical benefit within their remaining life. Patients with poor performance status (Karnofsky Performance Status less than 40 or an ECOG Performance greater than 3) - see Karnofsky and ECOG Performance Status scales below. Note that the higher a Karnofsky Performance Status is, the better a patient is doing. However, the lower an Eastern Cooperative Oncology Group (ECOG) Performance Status is, the better a patient is doing. Cobalt-60 pallidotomy is non-covered. Indications for Stereotactic Body Radiation Therapy (SBRT): SBRT is indicated for primary tumors and tumors metastatic to the lung, liver, kidney, adrenal gland, or pancreas. SBRT is indicated for treatment of pelvic and head and neck tumors that have recurred after primary irradiation. SBRT is indicated for patients with clinically localized, low- to intermediate-risk prostate cancer. SBRT treatment, of any body site or internal organ, is indicated for treatment of recurrence in or near previously irradiated regions when a high level of precision and accuracy or a high dose per fraction is indicated to minimize the risk of injury to surrounding normal tissues and treatment with conventional methods is not appropriate or safe for the particular patient (medical records must describe the specific circumstances, see documentation requirements in the attached Billing and Coding Article). Limitations for Stereotactic Body Radiation Therapy (SBRT): Primary treatment of lesions of bone, breast, uterus, ovary, and other internal organs not listed earlier in this LCD as covered is not considered medically necessary. SBRT is not considered medically necessary under the following circumstances for any condition: Treatment is unlikely to result in clinical cancer control and/or functional improvement. The tumor burden cannot be completely targeted with acceptable risk to critical normal structures. The patient has a poor performance status (Karnofsky Performance Status less than 40 or Eastern Cooperative Oncology Group (ECOG) Status of 3 or worse). Note that the higher a Karnofsky Performance Status is, the better a patient is doing. However, the lower an Eastern Cooperative Oncology Group (ECOG) Performance Status is, the better a patient is doing. Recurrent (other than pelvic and head and neck tumors) or metastatic disease could be treated by conventional methods (record must describe why other radiation therapy measures are not appropriate or safe for the particular patient). Since the goal of SBRT is to maximize the potency of the radiotherapy by completing an entire course of treatment within an extremely accelerated time frame, any course of radiation treatment extending beyond five fractions is not considered SBRT. SBRT is meant to represent a complete course of treatment and not to be used as a boost following a conventionally fractionated course of treatment. Karnofsky Performance Status Scale 100 Normal; no complaints, no evidence of disease 90 Able to carry on normal activity; minor signs or symptoms of disease 80 Normal activity with effort; some signs or symptoms of disease 70 Cares for self; unable to carry on normal activity or to do active work 60 Requires occasional assistance but is able to care for most needs 50 Requires considerable assistance and frequent medical care 40 Disabled; requires special care and assistance 30 Severely disabled; hospitalization is indicated although death not imminent 20 Very sick; hospitalization necessary; active supportive treatment is necessary 10 Moribund, fatal processes progressing rapidly 0 Dead Karnofsky DA, Burchenal JH. (1949). “The Clinical Evaluation of Chemotherapeutic Agents in Cancer.” In: MacLeod CM (Ed), Evaluation of Chemotherapeutic Agents. Columbia Univ Press . Page 196. ECOG Performance Status Scale Grade 0: Fully active, able to carry on all pre-disease performance without restriction. Grade 1: Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g. light house work, office work. Grade 2: Ambulatory and capable of all self-care but unable to carry out and work activities. Up and about more than 50% of waking hours. Grade 3: Capable of only limited self-care, confined to bed or chair more than 50% of waking hours. Grade 4: Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. Grade 5: Dead Am. J. Clin. Oncol.: Oken, M.M., Creech, R.H., Tormey, D.C., Horton, J., Davis, T.E., McFadden, E.T., Carone, P.P.; Toxicity And Response Criteria Of The Eastern Cooperative Oncology Group. Am J Clin Oncol. 1982;5:649-655.