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ModifiedBlue Cross Blue Shield - South DakotaPolicy 07.01.81

Laser Interstitial Thermal Therapy (LITT)

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This policy governs coverage and medical necessity criteria for MR-guided laser interstitial thermal therapy (LITT) for neurologic indications (brain tumors, radiation necrosis, and drug‑resistant epilepsy) for Blue Cross Blue Shield - South Dakota members.

Policy Summary

PayerBlue Cross Blue Shield - South Dakota

PolicyLaser Interstitial Thermal Therapy (LITT)

Policy CodePolicy 07.01.81

Change TypePolicy Revised (February 2025 annual review)

Effective DateDec 1, 2020

Last ReviewFeb 1, 2025

Next Review Date

Key ActionDocument prior therapies and demonstrate that the lesion or epileptogenic focus is surgically inaccessible or that open surgery is contraindicated when requesting coverage for LITT.

SourceLink

POLICY UPDATE CHANGES

Policy Revised during the February 2025 annual review.

3primary clinical indications

2FDA‑cleared systems

9.0-14.4glioblastoma OS (months)

46-61%seizure freedom (meta-analyses)

30%major procedure AEs

2020–2025revision timeline

Coverage and Medical Necessity Criteria

Tumors and Radiation Necrosis

Considered medically necessary when ANY one of the following is met:

Tumor or Radiation Necrosis Indications: LITT is medically necessary for treatment of (1) a progressive (primary or metastatic) or recurrent malignant glioblastoma or other glioma(s), OR (2) a lesion(s) inaccessible to surgical resection; includes symptomatic cranial radiation necrosis when policy criteria are met.

Supported by evidence summaries noting limited but suggestive data and relevant society guideline support.

Drug‑Resistant Epilepsy

Covered when ALL of the following are met:

Epilepsy criteria: (1) Documented disabling seizures despite the use of two or more tolerated antiepileptic drug regimens; AND (2) Documented (imaging or EEG) presence of well-defined epileptogenic foci accessible by laser interstitial thermal therapy (LITT).2 AED trials

Policy Summary

PayerBlue Cross Blue Shield - South Dakota

PolicyLaser Interstitial Thermal Therapy (LITT)

Policy CodePolicy 07.01.81

Change TypePolicy Revised (February 2025 annual review)

Effective DateDec 1, 2020

Last ReviewFeb 1, 2025

Next Review Date

Key ActionDocument prior therapies and demonstrate that the lesion or epileptogenic focus is surgically inaccessible or that open surgery is contraindicated when requesting coverage for LITT.

SourceLink

On This Page

Epileptogenic lesion must be accessible by LITT and AED trials must be appropriately chosen and tolerated.

Coverage criteria for LITT in intracranial tumors and radiation necrosis

Covered when ALL of the following are met

Indication: Patient has a primary or metastatic intracranial tumor that is surgically inaccessible or located adjacent to eloquent or radiosensitive areas, OR patient has symptomatic cranial radiation necrosis with insufficient or intolerable response to medical management.

Based on population descriptions and policy rationale.

Therapy intent and setting: LITT is intended as a less-invasive alternative when open surgery is contraindicated due to high procedural morbidity risk or comorbidities; may be used in first-line, adjunct, or salvage settings.

Reflects typical clinical use and policy context.

Diagnostic confirmation: Diagnosis is supported by imaging and clinical correlation; biopsy may be required to distinguish radiation necrosis from tumor recurrence when symptomatic or with worsening radiographic findings.

Document prior treatments and diagnostic steps per policy guidance.

Initial coverage criteria

Covered when ALL of the following are met for each indication

Radiation necrosis — candidate criteria: Patient has symptomatic cranial radiation necrosis with insufficient response or intolerance to medication management; open surgery (craniotomy/resection) is contraindicated or considered high risk due to procedural morbidity or comorbidities; diagnosis supported by imaging and/or biopsy when indicated; LITT is proposed as MRI-guided thermal ablation.

From populations and intervention descriptions.

Epilepsy — candidate criteria: Patient has drug-resistant epilepsy defined by failure of sustained seizure freedom after trials of ≥2 appropriately chosen and tolerated antiseizure medications; an identifiable epileptogenic focus amenable to targeted ablation (e.g., mesial temporal structures); LITT is proposed as MRI-guided thermal ablation as an alternative to open resection or neurostimulation.>= 2 AED trials

Based on ILAE definition and policy guidelines.

COVERAGE CRITERIA

Coverage may be considered when ALL of the following are met:

Patient selection: Patient has a clearly identified target lesion or epileptogenic focus that is inaccessible to or carries high surgical morbidity with open resection, or patient is a candidate for a less invasive approach and has been counseled on comparative outcomes.

Supported by population and clinical context descriptions.

Evidence-informed expectations: Provider acknowledges that pooled seizure freedom rates from meta-analyses range roughly 46%–61% with variability by etiology and that long-term comparative data versus open resection are limited.

Providers should counsel patients using summary rates from meta-analyses.

Counseling on risks and outcomes: Provider documents discussion of potential adverse events (overall AE rates reported ~14%–19% in systematic reviews) and that complication rates and long-term seizure freedom may be lower than conventional open surgery for some patients.

References systematic review complication and outcome estimates.

Follow-up and outcome measurement: A plan for follow-up and outcome measurement is provided, with preference for at least 1–3 years of clinical follow-up for seizure and survival outcomes, and standardized reporting of neuropsychological and quality-of-life measures when applicable.1-3 years preferred

Reflects evidence limitations and need for longer-term outcome data.

Laser interstitial thermal therapy (LITT) is considered investigational when the policy's medical necessity criteria are not met and for all other unlisted indications. Examples of investigational uses include LITT for liver cancer, lung cancer, osteoid osteoma, and prostate cancer, reflecting insufficient evidence to determine net health outcomes for these non‑CNS indications.

The evidence base for LITT is limited by predominantly retrospective study designs, small sample sizes, and heterogeneous patient populations, which vary by performance status, lesion volume and location, prior therapies, and extent of ablation. Systematic reviews report substantial heterogeneity and often lack contemporaneous comparator data, limiting the ability to draw definitive conclusions about comparative effectiveness and long‑term outcomes.

Use of LITT outside well‑defined, controlled patient populations or for indications not supported by clinical evidence may be excluded. This includes scenarios where standard noninvasive or medical therapies have not been attempted or documented (for example, corticosteroid‑refractory radiation necrosis without prior medical management) and where requisite diagnostic confirmation or demonstration that open surgery is contraindicated is absent.

LITT for miscellaneous non‑brain cancers (including liver, lung, osteoid osteoma, and prostate cancer) is not supported by adequate high‑quality evidence. Available studies are largely single‑arm case series or small nonrandomized comparative studies at high risk of bias, do not consistently report symptom relief or quality‑of‑life outcomes, and lack randomized comparisons to standard treatments; therefore current data do not justify routine coverage for these indications.

National Comprehensive Cancer Network (NCCN) guideline documents for several non‑CNS malignancies do not include LITT as a recommended therapy (examples: bone cancer, breast cancer, hepatocellular carcinoma, non‑small cell lung cancer, prostate cancer, and small cell lung cancer). The absence of LITT from these NCCN guidelines is noted as a factor weighing against routine use of LITT for these tumor types outside of research settings.

Within the excerpt provided there are no explicit blanket policy exclusions listed; however, clinical guideline statements and FDA advisories cited in the references may inform exclusionary considerations (for example, thermometry safety advisories and guideline omissions for non‑CNS cancers).

Use of LITT for indications that are not specified as medically necessary in this policy is considered investigational and not medically necessary due to insufficient high‑quality evidence supporting net health outcomes for those indications.

No explicit not‑medically‑necessary (NMN) statements are provided in this excerpt beyond investigational language; the document emphasizes evidence limitations and the need for prospective comparative studies to determine net health outcomes.

Comparative systematic reviews report higher long‑term rates of seizure freedom (Engel I) after conventional open surgical resections compared with LITT in some analyses. Therefore, LITT should not be considered a routine substitute for conventional open surgical resection when conventional surgery is feasible and expected to provide superior long‑term seizure outcomes.

Procedure Coding

Codes table referencedmixed

No codes listed

Covered CPT CodesCPTCovered

61736	Laser interstitial thermal therapy (LITT) of lesion, intracranial, including burr hole(s), with magnetic resonance imaging guidance, when performed; single trajectory for 1 simple lesion.
61737	Laser interstitial thermal therapy (LITT) of lesion, intracranial, including burr hole(s), with magnetic resonance imaging guidance, when performed; multiple trajectories for multiple or complex lesion(s).

Antiepileptic drug trials — ≥ 2 trials required

Required AED trialsDocumented disabling seizures despite trials of two or more tolerated and appropriately chosen antiepileptic drug (AED) regimens.

Documentation typeImaging or EEG evidence of a well‑defined epileptogenic focus accessible by LITT.

Definition referenceMedically refractory epilepsy defined as failure to become seizure free after adequate trials of two seizure medications chosen for the seizure type and tolerated by the individual.

Prior Authorization, Documentation, and Billing Actions

Billing Rule

Prior approval note

Prior approval is not applicable for this policy; however, providers must follow the billing and coding guidance in the Codes table when submitting claims.

Prior approval: Not applicable — billing must follow CPT codes 61736 and 61737 and the Type of Service and Place of Service guidance in the Codes section.

Prior Authorization

Prior authorization recommended for CNS LITT

Prior authorization is recommended for intracranial LITT to ensure appropriateness of the proposed procedure and to collect required clinical documentation prior to scheduling the intervention.

Prior authorization should document the indication, prior therapies or contraindications to standard therapies (e.g., open resection, SRS, WBRT, systemic therapy), lesion size and location, relation to eloquent cortex, and any subspecialty consultation (neurosurgery, neuro-oncology, or epilepsy specialist as applicable).
When prior authorization is requested, include imaging demonstrating the target and operative plan, and operative risk assessment that supports selection of LITT over open resection.

Prior Authorization

Prior authorization: demonstration of inaccessibility/contraindication and prior treatment considerations

For tumor or radiation necrosis indications, prior authorization should include documentation that the lesion is surgically inaccessible or open surgery is contraindicated, and that prior standard therapies were attempted or are not appropriate.

Document that the tumor or lesion is inaccessible to surgical resection or located adjacent to eloquent or radiosensitive cortex such that open resection confers unacceptable morbidity.
Document prior treatments and response: for tumors — prior SRS, WBRT, systemic therapy, or open resection when performed; for radiation necrosis — prior medication management including corticosteroids and, where used, bevacizumab, and whether noninvasive options (e.g., hyperbaric oxygen) have been considered.
If radiation necrosis is suspected and noninvasive diagnosis is inconclusive, include biopsy results if performed to confirm diagnosis.

Billing Rule

Prior authorization for LITT CPT codes

Prior authorization or utilization management processes should reference the procedure CPT codes and expected claim documentation to avoid coding-related denials.

Use CPT 61736 (single trajectory, 1 simple lesion) or CPT 61737 (multiple trajectories for multiple or complex lesions) when requesting authorization.
Indicate Type of Service = Surgery and the appropriate Place of Service (e.g., Inpatient vs outpatient) on claims.
Ensure claims include supporting documentation of medical necessity to reduce risk of denial related to coding or insufficient clinical information.

Denial Risk

Denial triggers for unsupported indications or unmet epilepsy criteria

Requests may be denied when the clinical indication is unsupported, when epilepsy criteria are not met, or when evidence is insufficient for the requested anatomic indication.

Denial triggers include: LITT for indications not meeting policy criteria (e.g., liver, lung, prostate, osteoid osteoma) because these are considered investigational; epilepsy without documentation of failure of two or more appropriate antiepileptic drug regimens; lack of documentation that the lesion is inaccessible to surgery or that standard therapies were tried or contraindicated.
Requests lacking required imaging, operative risk assessment, or subspecialty consultation may be denied for insufficient documentation.

Documentation Required

Clinical indication documentation

Clinical documentation should clearly state the diagnosis, symptoms, lesion characteristics, prior treatments and responses, and why LITT is selected over alternative therapies.

Diagnosis and symptom summary (e.g., progressive/recurrent malignant glioma, symptomatic radiation necrosis, or drug-resistant epilepsy).
Imaging reports (MRI) showing lesion location, size, and proximity to eloquent cortex; EEG data for epilepsy where applicable.
Documentation of multidisciplinary evaluation or neurosurgical consultation stating that open resection is contraindicated or carries excessive morbidity, or that lesion is anatomically inaccessible.
Operative plan describing targeted trajectory and anticipated approach, and biopsy results if performed to confirm diagnosis (e.g., to distinguish radionecrosis from recurrent tumor).

Documentation Required

Appropriate candidate justification

Justification that the patient is an appropriate candidate for LITT should include explanation of surgical contraindication or excessive risk with open surgery and/or patient preference for less invasive approach when clinically reasonable.

Explain why open craniotomy/resection is not feasible or is high risk (comorbidities, lesion location near eloquent cortex, prior surgeries or radiation increasing surgical risk).
Document seizures refractory to >=2 appropriately chosen and tolerated antiepileptic drugs for epilepsy indications, with localization of a discrete epileptogenic focus accessible to LITT.
For radiation necrosis, document corticosteroid-refractory symptoms or intolerance to medical therapy and justification for invasive therapy.
Include subspecialty consultation (neurosurgeon, neuro-oncologist, epilepsy specialist) supporting candidacy for LITT.

Denial Risk

Insufficient evidence for liver cancer indications

Evidence is limited and insufficient to support LITT for liver cancer; available studies are small, heterogeneous, and do not demonstrate symptom or quality-of-life benefit compared to standard therapies.

LITT for liver cancer is considered investigational per policy due to low-quality case series and nonrandomized comparative studies lacking control of tumor etiology and without symptom/QoL outcomes; prior authorization requests for liver indications are likely to be denied.
Prospective multicenter randomized trials focusing on specific tumor etiologies are needed to support coverage.

Denial Risk

Insufficient evidence for lung cancer indications

Evidence is limited and insufficient to support LITT for lung cancer; studies are small and nonrandomized and do not provide symptom, quality-of-life, or comparative effectiveness data.

LITT for lung cancer is considered investigational per policy; prior authorization requests for pulmonary indications should include high-quality evidence to justify off-label use or will be considered not medically necessary.
Randomized controlled trials comparing LITT with surgical resection, ablation alternatives, or systemic therapy by primary tumor type are needed.

Denial Risk

Evidence limitations may trigger denial

Because evidence for many non-brain indications is limited and heterogeneous, lack of robust comparative data or patient-oriented outcomes may lead to denial of coverage.

Other miscellaneous cancer indications (e.g., prostate, osteoid osteoma) lack adequate comparative studies and long-term outcome data; requests for these indications should include compelling rationale and supporting evidence.
When submitted evidence does not address key gaps (randomization, disease-specific cohorts, symptom/QoL outcomes, or long-term follow-up), utilization management may deny as investigational.

Documentation Required

Required documentation for epilepsy

For epilepsy indications, required documentation must confirm drug-resistant epilepsy and well-defined, LITT-accessible epileptogenic focus, including prior medication trials and diagnostic localization.

Document disabling seizures despite adequate trials of two or more appropriately chosen and tolerated antiepileptic drug (AED) regimens, consistent with ILAE definition of drug-resistant epilepsy.
Provide EEG and imaging (MRI) demonstrating the epileptogenic focus and that it is anatomically accessible to LITT.
Include seizure frequency baseline, prior epilepsy treatments, any prior epilepsy surgery or procedures, and subspecialty (epilepsy) consultation supporting LITT candidacy.

Documentation Required

Required documentation for tumor/radiation necrosis

For tumor or radiation necrosis indications, required clinical documentation should support progressive or recurrent malignant glioma or symptomatic radiation necrosis, lesion inaccessibility to open resection, and prior noninvasive or medical therapies attempted.

Clinical history and neurologic symptoms attributable to the lesion.
Imaging demonstrating recurrent or progressive tumor or features consistent with radiation necrosis; biopsy results when used to confirm radiation necrosis.
Documentation of prior therapies and responses: SRS, WBRT, systemic therapy, corticosteroids, bevacizumab, or other relevant medical management; and explanation why these are insufficient or contraindicated.
Multidisciplinary consultation notes indicating that LITT is an appropriate therapeutic alternative given surgical risk or lesion location.

Documentation Required

Required clinical documentation

Required clinical documentation overall should demonstrate indication, prior therapies/trials, imaging and diagnostic localization, and multidisciplinary assessment supporting LITT as the chosen intervention.

Indication and symptom burden, prior standard therapies and responses or contraindications, and rationale for LITT selection.
High-quality imaging (MRI) and, for epilepsy, EEG localization data; biopsy results when performed.
Consultation notes from relevant specialists (neurosurgery, neuro-oncology, epilepsy) and operative planning details to support medical necessity.

Documentation Required

Prior medical therapy

For radiation necrosis, prior medical therapy should be documented and noninvasive options tried before invasive procedures when clinically appropriate.

Document trials of corticosteroids and response or intolerance.
If used or considered, document bevacizumab therapy and response or intolerance.
Consideration and trial of other noninvasive options (e.g., hyperbaric oxygen) per guideline recommendations should be documented when applicable before proceeding to LITT.

Note

Comparator consideration before LITT

Comparators such as open resection, stereotactic radiosurgery, radiotherapy (including WBRT), and systemic therapies should be considered prior to LITT when they are feasible and appropriate for the patient.

Document why standard comparators are not appropriate or have been exhausted (e.g., prior SRS with progression, systemic therapy failure, or unacceptable surgical risk).
When alternatives remain viable, provide rationale for selecting LITT over these comparators in the prior authorization documentation.

Step Therapy

Step therapy considerations for radiation necrosis

Step therapy considerations for radiation necrosis: noninvasive treatments (corticosteroids, bevacizumab, hyperbaric oxygen) should be considered and documented prior to invasive interventions when clinically reasonable.

Patients with corticosteroid-refractory symptoms can be considered for LITT after noninvasive therapies have been tried and documented.
Prior authorization should include documentation of trials of medical management and reasons for escalation to LITT (refractory symptoms, intolerance, or contraindication to medical therapy).

Step Therapy

Step therapy

There are no explicit generic step-therapy requirements in this policy text beyond indication-specific prior trials and documentation; follow the clinical-criteria requirements (e.g., two AED trials for epilepsy) and guideline-recommended treatment sequences.

Operationally, requests should document adherence to the policy-specific prerequisites (e.g., AED trials for epilepsy, prior medications for radiation necrosis) to avoid denial.
If institutional or payer-specific step-therapy programs exist, follow those protocols in addition to the policy criteria.

Clinical and Technical Background

BACKGROUND: Laser interstitial thermal therapy (LITT) is a minimally invasive, MR‑guided technique that delivers thermal energy via a laser fiber probe to create a targeted thermal ablation zone within intracranial lesions while monitoring tissue temperature with real‑time MR thermography. LITT is proposed as an alternative to open craniotomy/resection, stereotactic radiosurgery, or neurostimulation for selected intracranial tumors, radiation necrosis, and drug‑resistant epilepsy, particularly when lesions are surgically inaccessible or adjacent to eloquent brain structures.

Key Definitions

Medically refractory epilepsy — definition

DefinitionFailure to achieve seizure freedom after adequate trials of two appropriately chosen and tolerated antiepileptic drugs, used alone or in combination.

Clinical implicationRequired documentation: disabling seizures despite ≥2 tolerated, appropriately chosen AED regimens and imaging/EEG confirming a targetable focus.

Reference contextDefinition aligned with ILAE consensus and policy guidelines for medically refractory epilepsy.

LITT — MR‑guided interstitial laser ablation

Procedure descriptionMR‑guided interstitial laser ablation using a transcranial burr hole with real‑time MR thermography monitoring to create a targeted thermal zone.

Guidance modalityPerformed under real‑time MRI guidance with actively cooled applicators and MR thermography monitoring.

Typical indicationsMost neurological uses involve ablation of primary/metastatic brain tumors, epileptogenic foci, and radiation necrosis in surgically inaccessible or eloquent areas.

LITT — stereotactic laser ablation (definition)

Alternate nameAlso called stereotactic laser ablation or stereotactic laser interstitial thermal therapy.

Operational settingPerformed under real‑time MRI guidance with probe placement through a burr hole and MRI‑monitored ablation control.

MechanismThermal destruction via DNA damage, protein denaturation, coagulative necrosis and vessel sclerosis to create a sharp thermal border.

Radiation necrosis — definition and features

DefinitionDelayed treatment‑induced brain tissue necrosis typically developing 1–3 years after cranial irradiation, more likely with high‑dose fractionation or radiosensitizers.

Clinical featuresMay present with focal neurologic deficits, increased intracranial pressure, or seizures (≈20% incidence).

Diagnostic noteDistinguishing radiation necrosis from tumor recurrence can be difficult; biopsy may be required for definitive diagnosis when symptomatic or radiographic worsening occurs.

Radiation necrosis — timing, risks, and treatment context

TimingTypically develops 1–3 years after cranial irradiation.

Risk factorsHigher likelihood with high‑dose fractionation and possibly concurrent chemotherapy or radiosensitizers.

Treatment contextConsider LITT for symptomatic cranial radiation necrosis with insufficient response or intolerance to medication management when open surgery is contraindicated.

Drug‑resistant epilepsy — definition and context

DefinitionFailure to achieve sustained seizure freedom despite adequate trials of 2 or more appropriately chosen and tolerated antiseizure medications (ILAE definition).

PopulationIncludes patients with identifiable epileptogenic foci (e.g., mTLE) who may be candidates for targeted ablation.

EpidemiologyApproximately one‑third of patients with epilepsy do not achieve adequate seizure control with antiepileptic drugs.

LITT — MRI‑guided focused thermal ablation (overview)

Procedure summaryMRI‑guided laser interstitial thermal therapy: focused thermal ablation under real‑time MRI guidance as an alternative to open craniotomy.

Use casesOffered as alternative to open resection, SRS, or neurostimulation for tumors, radiation necrosis, or epilepsy when surgery is high‑risk or targetable by LITT.

Common complicationsIncludes transient or permanent weakness, cerebral edema, hemorrhage, seizures, and hyponatremia; delayed deficits often respond to corticosteroids.

Population of interest for LITT

Primary populationIndividuals with primary or metastatic intracranial tumors that are surgically inaccessible or located near eloquent/radiosensitive areas.

Epilepsy populationIndividuals with drug‑resistant epilepsy who have an identifiable epileptogenic focus amenable to targeted LITT and who have failed ≥2 AEDs.

Radiation necrosis populationIndividuals with symptomatic cranial radiation necrosis with insufficient response or intolerance to medical management where open surgery is contraindicated.

MR‑guided LITT (MRgLITT) — definition and guideline context

MR‑guided LITT (MRgLITT)Magnetic resonance–guided LITT is a minimally invasive, image‑guided technique for targeted thermal ablation of intracranial lesions under real‑time MRI thermography.

Guideline contextProfessional society statements (AANS‑CNS, ISRS) conditionally support LITT for selected patients with tumors or corticosteroid‑refractory radiation necrosis; evidence quality is limited.

Clinical roleConsidered when open resection is contraindicated or carries high procedural morbidity; may be used in first‑line, adjunct, or salvage settings depending on patient factors.

LITT — CPT coding (selected codes)

CPT 61736Laser interstitial thermal therapy (LITT) of lesion, intracranial, including burr hole(s), with MRI guidance; single trajectory for 1 simple lesion.

CPT 61737Laser interstitial thermal therapy (LITT) of lesion, intracranial, including burr hole(s), with MRI guidance; multiple trajectories for multiple or complex lesion(s).

Claim reportingUse appropriate CPT codes and designate Type of Service as Surgery; Place of Service may be Inpatient when applicable.

Policy Revision Timeline

2025-02annual_review_revisionLatest

Policy revised during the February 2025 annual review.

2024-02annual_review_renewed

Policy renewed during the February 2024 annual review.

2023-12annual_review_revision

Policy revised during the December 2023 annual review.

2022-12annual_review_revision

Policy revised during the December 2022 annual review.

2021-12annual_review_revision

Policy revised during the December 2021 annual review.

2020-12policy_created

New medical policy created in December 2020.