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Radiotherapy (RT) is an integral component in the treatment of head and neck cancers. Intensity-modulated radiotherapy (IMRT) has been proposed as a method of RT that allows adequate RT to the tumor while minimizing the radiation dose to surrounding normal tissues and critical structures.
Conventional external beam RT. Over the past several decades, methods to plan and deliver RT 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 radiotherapy (EBRT).
Three-dimensional conformal radiation. 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 radiotherapy. IMRT, which uses computer software and CT images, 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 multiply-shaped treatment fields. It uses a device (a multileaf collimator) 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 may thus 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.
Because 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.
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.
Head and Neck Tumors
Head and neck cancers account for about 3% to 5% of cancer cases in the United States. The generally accepted definition of head and neck cancers includes cancers arising in the oral cavity and lip, larynx, hypopharynx, oropharynx, nasopharynx, paranasal sinuses and nasal cavity, salivary glands, and occult primaries in the head and neck region. Cancers generally not considered as head and neck cancers include uveal and choroidal melanoma, cutaneous tumors of the head and neck, esophageal cancer, and tracheal cancer. Thyroid cancers are also addressed in this policy. External beam radiotherapy is uncommonly used in the treatment of thyroid cancers but may be considered in patients with anaplastic thyroid cancer and for locoregional control in patients with incompletely resected high-risk or recurrent differentiated (papillary, follicular, or mixed papillary-follicular) thyroid cancer.
POLICYIntensity-modulated radiation therapy may be considered medically necessary for the treatment of head and neck cancers.
Intensity-modulated radiation therapy may be considered medically necessary for the treatment of thyroid cancers in close proximity to organs at risk (esophagus, salivary glands, and spinal cord) and 3-D CRT planning is not able to meet dose volume constraints for normal tissue tolerance. (see Policy Guidelines).
Intensity-modulated radiation therapy is not medically necessary for the treatment of thyroid cancers for all indications not meeting the criteria above.
POLICY EXCEPTIONSFederal Employee Plan: Effective January 1, 2010, prior approval for outpatient IMRT is required. As of July 1, 2010, prior approval is no longer required for outpatient IMRT provided for the treatment of head and neck cancers.
Federal 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 GUIDELINESFor this policy, head and neck cancers are cancers arising from the oral cavity and lip, larynx, hypopharynx, oropharynx, nasopharynx, paranasal sinuses and nasal cavity, salivary glands, and occult primaries in the head and neck region.
Organs at risk are defined as normal tissues whose radiation sensitivity may significantly influence treatment planning and/or prescribed radiation dose. These organs at risk may be particularly vulnerable to clinically important complications from radiation toxicity. The following table outlines radiation doses that are generally considered tolerance thresholds for these normal structures in the area of the thyroid.
Radiation Tolerance Doses for Normal Tissues
aTD 5/5, the average dose that results in a 5% complication risk within 5 years
bTD 50/5, the average dose that results in a 50% complication risk within 5 years
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member’s specific benefit plan language.
POLICY HISTORY5/26/2009: Policy added
7/16/2009: Approved by Medical Policy Advisory Committee (MPAC)
12/28/2009: Added Prior Approval for FEP members effective January 1, 2010. Also corrected a typographical error, changed CPT Code 77148 to 77418.
07/16/2010: Policy Exceptions section revised to state that as of July 1, 2010, prior approval is no longer required for outpatient IMRT provided for the treatment of head and neck cancers for FEP members.
08/17/2010: Add CPT code 77338 to the Covered Codes table.
12/30/2010: Policy statement revised to indicate that intensity-modulated radiation therapy is considered investigational for the treatment of thyroid cancers.
07/19/2012: Policy statement on head and neck cancers unchanged. Policy statement on thyroid tumors changed from investigational to the following: Intensity-modulated radiation therapy is considered medically necessary for the treatment of thyroid cancers in close proximity to organs at risk (esophagus, salivary glands, and spinal cord) and 3-D CRT planning is not able to meet dose volume constraints for normal tissue tolerance. Policy guidelines updated regarding radiation tolerance doses for normal tissues (esophagus, salivary glands, spinal cord). Added ICD-9 code 193 to the Covered Codes table.
08/13/2012: Added ICD-9 code 195.0 to the Covered Codes table.
10/23/2013: Policy reviewed; no changes.
08/12/2014: Policy title changed from "Intensity-Modulated Radiation Therapy (IMRT) Head and Neck Cancers" to "Intensity-Modulated Radiotherapy: Cancer of the Head and Neck or Thyroid." Policy description updated regarding radiation techniques. Second medically necessary policy statement revised to change "is" to "may be." Added the following statement: Intensity-modulated radiation therapy is not medically necessary for the treatment of thyroid cancers for all indications not meeting the criteria above.
SOURCESBlue Cross & Blue Shield Association policy # 8.01.48
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.