Appeal type: Medical necessity
Decision: Overturned

Diagnosis: Trigeminal schwannoma
Treatment: Proton Beam Therapy 

The proposed proton beam therapy is medically necessary.

This is a male with history of testicular cancer who has developed a 2.5 centimeter (cm) trigeminal schwannoma involving right cavernous sinus and Merkel's cave at the base of the skull.

This patient's clinical condition is similar to skull base chordoma with tumor involving in the base of skull. The dose of radiation required to control schwannoma has high risk of radiation damage to the brainstem. It is critical to achieve sharp dose gradient to the tumor in order to avoid radiation complications to these critical normal tissues. Compared to photon beam radiation therapy (RT), proton beam RT can achieve significantly sharper dose gradient due to its Bragg peak patterns of energy release and can deliver therapeutic high dose to target with significantly better dose conformity and sparing of adjacent normal tissues. Thus, proton beam with its physical advantage of being able to deposit a high dose of radiation to the tumor with sharp dose fall off from normal tissues, improves the probability of local control with reduced complications in this man. Proton beam with superior dose conformity is able to deliver high dose to the tumor with maximum sparing of adjacent brain and brainstem and will decrease risks of such complications in this patient. Multiple single institutional studies of proton radiotherapy for skull base tumor such as chordoma and meningioma demonstrate at least equivalent tumor control with minimum complications. 

The 2017 ASTRO Proton Beam Therapy Model Policy states that proton beam therapy is an advanced type of external-beam radiation therapy that uses proton rather than photon beams to deliver radiation doses to a tumor. Proton therapy offers a high degree of precision, which allows radiation oncologists to target an escalated dose of radiation directly on a tumor and spare nearby healthy tissue. Proton therapy is particularly beneficial for patients with tumors that are near critical structures, such as lung tumors near the heart.  Based on new evidence published since the original policy was issued in 2014, the updated model policy outlines two categories of appropriate clinical indications, or diagnoses, for proton beam therapy. For indications in Group-1, coverage is recommended; for Group-2, coverage is recommended if additional requirements (outlined below) are met. Disease sites were assigned to one of the two categories based on evidence in published clinical data and current Medicare coverage. Group-1 indications, or the clinical scenarios that frequently support the use of proton therapy based on medical necessity and published clinical data, were updated with five additions and one modification. Group-1 indications, with additions marked by asterisks, include:
Malignant and benign primary central nervous system (CNS) tumors*
Tumors that approach or are located at the base of skull, including but not limited to chordoma and chondrosarcomas etc.

Thus, the requested proton beam to treat skull base schwannoma is consistent with the 2017 ASTRO model policy for proton beam therapy.