MA: Intensity Modulated Radiation Therapy (IMRT) (Preauthorization Required)

Intensity-modulated radiotherapy (IMRT) is an established technique of radiation planning and delivery that uniquely sculpts the radiation to the target volume more precisely in order to: 1) decrease the exposure in the surrounding normal tissues, thus reducing acute toxicity; and 2) increase the dose to the tumor target, thus potentially reducing local recurrence rates. With IMRT, the target volume can be treated with different fraction sizes simultaneously. A variety of delivery techniques are available. For example, the beam can be shaped as it exits a linear accelerator (linac) using a multi-leaf collimator (MLC) that blocks or "collimates" the beam to create curved edges. A computer can vary the aperture size continuously and independently for each MLC leaf pair, dividing the beam into "beamlets." IMRT has been promoted over non-modulated external beam radiation, two-dimensional (2D) and three-dimensional (3D) conformal techniques on the basis of computer planning studies that have shown better planning target volume coverage and better sparing of organs at risk. 

IMRT aims radiation at the tumor from many more directions, and thus subjects more normal tissue to low-dose radiation than occurs with conventional EBRT or 3 dimensional conformal radiation therapy (3D-CRT). This may increase late effects of radiation therapy. Treatment planning and delivery are more complex, time consuming and labor-intensive for IMRT than for 3D-CRT. Clinical studies must test whether IMRT improves tumor control or reduces acute and late toxicities, when compared with 3D-CRT.

Other advanced techniques may further improve radiotherapy (RT) treatment by improving dose distribution. These techniques are considered variations of IMRT. Volumetric modulated arc therapy (VMAT) delivers radiation from a continuous rotation of the radiation source. The principal advantage of volumetric modulated arc therapy is greater efficiency in treatment delivery time, reducing radiation exposure and improving target radiation delivery due to less patient motion. Image-guided RT involves the incorporation of imaging before and/or during treatment to more precisely deliver RT to the target volume. 

Policy

1. Intensity Modulated Radiation Therapy (IMRT) may be considered Scientifically Validated for the following:
   
   1. Prostate Cancer
   2. Head and Neck Cancer
      
      1. orbits
      2. sinuses
      3. skull base
      4. aero-digestive tract within the head, neck and salivary glands
      5. supraglottic laryngeal
   3. Central Nervous System lesion
   4. Primary Malignant Gynecologic tumors (cervical, endometrial and vulvar cancers)
   5. Anal Cancer
   6. Patient who require repeat irradiation of a field which includes the spinal cord when the same region of the spinal cord was exposed to a cumulative dose of greater than 40 Gy during prior irradiation treatment
   7. Lung cancer when the following criteria are met:
      
      1. radiotherapy is being given with curative intent AND
      2. three-dimensional conformal radiotherapy will expose greater than 35% of normal lung tissue to more than a 20-Gy dose volume (V20) AND
      3. IMRT dosimetry demonstrates a reduction in the V20 to at least 10% below the V20 that is achieved with the three-dimensional plan (e.g. from 40% down to 30% or lower) OR
      4. If necessary to get the heart dose below 20Gy and/or to get volume of the heart that gets more than 50Gy under 25%
   8. Abdominal and pelvic cancer (stomach, hepatobiliary tract, pancreas, esophageal cancer) planning and clinical rationale demonstrates superior treatment to 3D CRT
   9. Whole breast irradiation in patients receiving treatment for left sided breast cancer after breast conserving surgery when all of the following are met:
      
      1. significant cardiac radiation exposure cannot be avoided using alternative radiation technique AND
      2.  IMRT dosimetry demonstrates significantly reduced cardiac target volume radiation exposure (see guidelines)
   10. 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 using IMRT.
   11. Individuals with recurrent tumors or target tissue that includes the far medial chest wall, internal mammary nodal area, or sternum, with or without intact breast. 
2. Intensity Modulated Radiation Therapy (IMRT) is investigational when the above criteria are not met.
3. Intensity Modulated Radiation Therapy (IMRT) is investigational for all other diagnoses, including but not limited to:
   
   1. Palliative treatment for lung cancer

NOTE: Volumetric modulated arc therapy (VMAT) is a form of IMRT.

Guidelines

The following are an example of clinical guidelines that may be used with IMRT in left-sided breast lesions:

• The target volume coverage results in cardiac radiation exposure that is expected to be greater than or equal to 25 Gy to 10 cc or more of the heart (V25 greater than or equal to 10 cc) with 3D conformal RT despite the use of a complex positioning device (such as Vac-Lok™), and 
• with the use of IMRT, there is a reduction in the absolute heart volume receiving 25 Gy or higher by at least 20% (e.g., volume predicted to receive 25 Gy by 3D RT is 20 cc and the volume predicted by IMRT is 16 cc or less).

Practice Guidelines and Position Statements

Guidelines or position statements will be considered for inclusion in ‘Supplemental Information’ if they were issued by, or jointly by, a US professional society, an international society with US representation, or National Institute for Health and Care Excellence (NICE). Priority will be given to guidelines that are informed by a systematic review, include strength of evidence ratings, and include a description of management of conflict of interest.
 
Breast Cancer

Current National Comprehensive Cancer Network (NCCN) guidelines (v.2.2024 ) for breast cancer indicate the importance of individualizing RT planning and delivery.¹⁰, Specifically, the guidelines note that "treatment planning should be optimized to maximally improve homogeneity across the target volume while minimizing dose to organs at risk." A related discussion section in this guideline states the following: "CT [computed tomography]-based treatment planning is encouraged to delineate target volumes and adjacent organs at risk. Greater target dose homogeneity and sparing of normal tissues can be accomplished using compensators such as wedges, forward planning using segments, and IMRT. Respiratory control techniques including deep inspiration breath-hold and prone positioning may be used to try to further reduce dose to adjacent normal tissues, particularly the heart and lung. In the post-mastectomy setting the guidelines state, "Based on anatomic considerations and presence of reconstruction, various 3-
D-, IMRT, or VMAT [volumetric modulated arc therapy] techniques using photons and/or electrons are appropriate."

Lung Cancer

Current NCCN guidelines (v.5.2024 ) for NSCLC indicate that "More advanced technologies are appropriate when needed to deliver curative RT safely. These technologies include (but are not limited to) … IMRT/VMAT [volumetric modulated arc therapy]…. Nonrandomized comparisons of using advanced technologies versus older techniques demonstrate reduced toxicity and improved survival."¹¹,

Current NCCN guidelines (v.2.2024 ) for SCLC indicate that "Use of more advanced technologies is appropriate when needed to deliver adequate tumor doses while respecting normal tissue dose constraints."¹², Among the technologies listed is IMRT. The guidelines also state that "IMRT is preferred over 3D [3-dimensional] conformal external-beam RT on the basis of reduced toxicity in the setting of concurrent chemotherapy/RT."
 
 
Head and Neck 

The National Comprehensive Cancer Network (NCCN; v4.2024 ) guideline on head and neck cancers notes that: "Advanced RT [radiation therapy] technologies such as IMRT (preferred), tomotherapy, VMAT [volumetric modulated arc therapy], image-guided RT (IGRT), and PBT [proton beam therapy] may offer clinically relevant advantages in specific instances to spare important organs at risk (OARs)...and decrease the risk for late, normal tissue damage while still achieving the primary goal of local tumor control.¹⁴, The demonstration of clinically significant dose-sparing of these OARS reflects best clinical practice."

The NCCN guideline also notes that "randomized studies to test [advanced radiation therapy technologies] are unlikely to be done since specific clinical scenarios represent complex combinations of multiple variables. In light of that, the modalities and techniques that are found best to reduce the doses to the clinically relevant OARs without compromising target coverage should be considered."The NCCN (v2.2024 ) guideline for thyroid cancer states, "The multidisciplinary team should carefully weigh the potential for benefit and the expected acute and chronic toxicity from EBRT [external-beam radiotherapy] when deciding when to incorporate EBRT into an individual patient’s treatment plan." They also recommend, "Conformal radiotherapy techniques including (IMRT) with simultaneous integrated boost (SIB) and image guidance are strongly encouraged in the adjuvant/definitive setting given the potential for reduced toxicity."¹⁵,

Gastrointestinal Tract Cancers

The National Comprehensive Cancer Network (NCCN) guideline (v.1.2024 ) for gastric cancer indicates that "CT [computed tomography] simulation and conformal treatment planning should be used with either 3D conformal radiation [3D-CRT] or intensity-modulated radiation therapy (IMRT)."¹⁷, In addition, target volumes need to be carefully defined and encompassed while taking into account variations in stomach filling and respiratory motion.

The NCCN guideline (v.1.2024 ) for hepatocellular carcinoma states that "All tumors irrespective of the location may be amenable to RT [radiation therapy] (3D conformal RT , intensity-modulated radiation therapy [IMRT], or SBRT [stereotactic body radiation therapy])."¹⁸, The NCCN guideline (v.2.2024 ) on biliary tract cancers also states that "all tumors irrespective of the location may be amenable to RT (3D-CRT, IMRT, or SBRT)."_¹⁹

IMRT is mentioned as an option in the NCCN guideline (v.2.2024 ) for pancreatic adenocarcinoma, stating that IMRT "is increasingly being applied for therapy of locally advanced pancreatic adenocarcinoma and in the adjuvant setting with the aim of increasing radiation dose to the gross tumor while minimizing toxicity to surrounding tissues."²⁰, In addition, the guideline states that "there is no clear consensus on the appropriate maximum dose of radiation when IMRT is used."
 
Gynecologic Cancers

For cervical cancer, the NCCN guideline (v.3.2024 ) indicates IMRT "is preferred to minimize toxicities in definitive treatment of the pelvis with or without the para-aortic region" and is "helpful in minimizing the dose to the bowel and other critical structures in the post-hysterectomy setting and in treating the para-aortic nodes when necessary." This technique can also be useful "when high doses are required to treat gross disease in regional lymph nodes."²¹, IMRT "should not be used as routine alternatives to brachytherapy for treatment of central disease in patients with an intact cervix." The guideline also mentions that "very careful attention to detail and reproducibility (including consideration of target and normal tissue definitions, patient and internal organ motion, soft tissue deformation, and rigorous dosimetric and physics quality assurance) is required for proper delivery of IMRT and related highly conformal technologies."

The NCCN guideline (v.2.2024 ) on uterine neoplasms states that radiotherapy for uterine neoplasms includes external-beam radiotherapy and/or brachytherapy but that IMRT may be considered "for normal tissue sparing."²²,

The NCCN guideline (v.1.2024 ) on ovarian cancer does not mention IMRT.²³

Anorectal Cancers

The NCCN guideline (v.1.2024 ) for anal carcinoma states that IMRT "is preferred over 3D conformal RT (3D-CRT) in the treatment of anal carcinoma" and that its use "requires expertise and careful target design to avoid reduction in local control by so-called ‘marginal-miss'."^24,

The NCCN guideline (v.2.2024 ) on rectal cancer indicates that "IMRT is preferred for reirradiation of previously treated patients with recurrent disease, patients treated postoperatively due to increased acute or later toxicity, or in unique anatomical situations."²⁵,

Esophageal Cancer

The NCCN guideline (v.3.2024 ) for esophageal and esophagogastric junction cancers states that "CT stimulation and conformal treatment planning should be used with either 3D conformal radiation or intensity-modulated radiation therapy (IMRT)."²⁶,

Central Nervous System

The National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines on Central Nervous System Cancers ( v.1.2024) support the use of highly conformal fractionated radiotherapy (RT) techniques (eg, IMRT) to "spare critical structures and uninvolved tissue."²⁸, When RT is given to patients with low-grade gliomas, NCCN states that "every attempt should be made to decrease the RT dose outside the target volume. This can be achieved with 3-dimensional (3D) planning or IMRT, with improved target coverage and normal brain/critical structure sparing often shown with IMRT." The guideline also states that for high-grade gliomas: "conformal RT (CRT) techniques, which include 3D-CRT and IMRT are recommended for performing focal brain irradiation. IMRT often will provide superior dosimetric target coverage and better sparing of critical structures than 3D-CRT."

For patients with brain metastases and a prognosis of 4 months or longer, the guidelines recommend hippocampal-sparing WBRT and memantine during and after WBRT for a total of 6 months.²⁸, The guidelines did not include recommendations for the use of IMRT to treat high-grade tumors as well as limited or extensive metastases to the central nervous system.
 
Medicare National Coverage

There is no national coverage determination. In the absence of a national coverage determination, coverage decisions are left to the discretion of local Medicare carriers.

Codes

77301	77338	77385	77386	77399
G6015	G6016