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DESCRIPTIONRadiation therapy is an integral component in the treatment of breast and lung cancers. Intensity modulated radiation therapy (IMRT) has been proposed as a method of radiation therapy that allows adequate radiation therapy to the tumor while minimizing the radiation dose to surrounding normal tissues and critical structures.
For certain stages of many cancers, including breast and lung, randomized clinical trials have shown that postoperative radiation therapy improves outcomes for operable patients. Adding radiation to chemotherapy also improves outcomes for those with inoperable lung tumors that have not metastasized beyond regional lymph nodes.
Conventional external-beam radiation therapy. Over the past several decades, methods to plan and deliver radiation therapy have evolved in ways that permit more precise targeting of tumors with complex geometries. Most early trials used 2-dimensional treatment planning, based on flat images and radiation beams with cross-sections of uniform intensity that were sequentially aimed at the tumor along 2 or 3 intersecting axes. Collectively, these methods are termed “conventional external beam radiation therapy”.
3-dimensional conformal radiation (3D-CRT). Treatment planning evolved by using 3-dimensional images, usually from computed tomography (CT) scans, to delineate the boundaries of the tumor and discriminate tumor tissue from adjacent normal tissue and nearby organs at risk for radiation damage. Computer algorithms were developed to estimate cumulative radiation dose delivered to each volume of interest by summing the contribution from each shaped beam. Methods also were developed to position the patient and the radiation portal reproducibly for each fraction and immobilize the patient, thus maintaining consistent beam axes across treatment sessions. Collectively, these methods are termed 3-dimensional conformal radiation therapy (3D-CRT).
Intensity-modulated radiation therapy (IMRT). IMRT, which uses computer software, CT images, and magnetic resonance imaging (MRI), offers better conformality than 3D-CRT as it is able to modulate the intensity of the overlapping radiation beams projected on the target and to use multiple-shaped treatment fields. It uses a device (a multileaf collimator, MLC) which, coupled to a computer algorithm, allows for “inverse” treatment planning. The radiation oncologist delineates the target on each slice of a CT scan and specifies the target’s prescribed radiation dose, acceptable limits of dose heterogeneity within the target volume, adjacent normal tissue volumes to avoid, and acceptable dose limits within the normal tissues. Based on these parameters and a digitally reconstructed radiographic image of the tumor and surrounding tissues and organs at risk, computer software optimizes the location, shape, and intensities of the beams ports, to achieve the treatment plan’s goals.
Increased conformality may permit escalated tumor doses without increasing normal tissue toxicity and thus may improve local tumor control, with decreased exposure to surrounding normal tissues, potentially reducing acute and late radiation toxicities. Better dose homogeneity within the target may also improve local tumor control by avoiding underdosing within the tumor and may decrease toxicity by avoiding overdosing.
Since most tumors move as patients breathe, dosimetry with stationary targets may not accurately reflect doses delivered within target volumes and adjacent tissues in patients. Furthermore, treatment planning and delivery are more complex, time-consuming, and labor-intensive for IMRT than for 3D-CRT. Thus, clinical studies must test whether IMRT improves tumor control or reduces acute and late toxicities when compared with 3D-CRT.
Methodologic Issues with IMRT Studies
Multiple-dose planning studies have generated 3D-CRT and IMRT treatment plans from the same scans, then compared predicted dose distributions within the target and in adjacent organs at risk. Results of such planning studies show that IMRT improves on 3D-CRT with respect to conformality to, and dose homogeneity within, the target. Dosimetry using stationary targets generally confirms these predictions. Thus, radiation oncologists hypothesized that IMRT may improve treatment outcomes compared with those of 3D-CRT. However, these types of studies offer indirect evidence on treatment benefit from IMRT, and it is difficult to relate results of dosing studies to actual effects on health outcomes.
Comparative studies of radiation-induced side effects from IMRT versus alternative radiation delivery are probably the most important type of evidence in establishing the benefit of IMRT. Such studies would answer the question of whether the theoretical benefit of IMRT in sparing normal tissue translates into real health outcomes. Single-arm series of IMRT can give some insights into the potential for benefit, particularly if an adverse effect that is expected to occur at high rates is shown to decrease by a large amount. Studies of treatment benefit are also important to establish that IMRT is at least as good as other types of delivery, but in the absence of such comparative trials, it is likely that benefit from IMRT is at least as good as with other types of delivery.
POLICYIntensity-modulated radiation therapy (IMRT) may be considered medically necessary as a technique to deliver whole breast irradiation in patients receiving treatment for left-sided breast cancer after breast-conserving surgery when all the following conditions have been met:
Intensity-modulated radiation therapy (IMRT) may be considered medically necessary in individuals with large breasts when treatment planning with 3D conformal results in hot spots (focal regions with dose variation greater than 10% of target) and the hot spots are able to be avoided with IMRT. (See Policy Guidelines.)
Intensity modulated radiation therapy (IMRT) of the breast is considered investigational as a technique of partial breast irradiation after breast-conserving surgery.
Intensity modulated radiation therapy (IMRT) of the chest wall is considered investigational as a technique of postmastectomy irradiation.
Intensity-modulated radiation therapy (IMRT) may be considered medically necessary as a technique to deliver radiation therapy in patients with lung cancer when all of the following conditions are met:
Intensity-modulated radiation therapy (IMRT) is considered not medically necessary as a technique to deliver radiation therapy in patients receiving palliative treatment for lung cancer.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESThe following are an example of clinical guidelines that may be used with IMRT in left-sided breast lesions:
The following are examples of criteria to define large breast size when using IMRT to avoid hot spots, as derived from randomized studies:
Investigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY7/23/2007: Policy added
11/15/2007: Policy approved by MPAC
5/11/2009: Policy reviewed, no changes
08/17/2010: Policy description unchanged. Policy statement regarding IMRT as a technique to deliver whole breast irradiation in patients receiving treatment for breast cancer after breast-conserving surgery was changed from investigational to not medically necessary. IMRT as a technique of partial breast irradiation after breast-conserving surgery remains investigational. Policy statement regarding use of IMRT in lung cancer was changed from investigational to not medically necessary. FEP verbiage added to the Policy Exceptions sections. Added new CPT code 77338 to the Code Reference section.
12/30/2010: Policy reviewed; no changes.
04/26/2012: Policy description updated regarding treatment techniques. Added policy statement to indicate that chest wall IMRT postmastectomy is investigational. Added policy statement to indicate that whole breast IMRT may be medically necessary in large-sized breasts. Changed policy statements regarding whole breast and lung IMRT from not medically necessary to medically necessary if certain conditions are met. Policy statement on partial breast IMRT remains investigational. Added statement to indicate that IMRT of the chest wall is considered investigational as a technique of postmastectomy irradiation. Policy guidelines updated regarding patient selection criteria. The Code Reference section was changed from non-covered to covered; added ICD-9 codes 162.3 - 162.9, 174.0 - 174.9, 175.0 - 175.9 as covered diagnoses.
08/09/2013: Policy reviewed; no changes.
SOURCE(S)Blue Cross Blue Shield Association Policy # 8.01.46
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.
The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.