PTC CLINIC
Information for Healthcare Professionals

The Proton Therapy Center in Prague uses unique and innovative treatment procedures that minimize undesirable exposure of the surrounding tissues, such as the optic and auditory nerve, hippocampus or brain stem to radiation. The benefits of proton radiotherapy for tumors of the central nervous system may already be seen in the course of treatment when the vast majority of patients are able to undergo treatment without hospitalization.

Proton radiotherapy is suitable for:

1. Low-grade glioma

• Adjuvant or radical radiotherapy (when resection is not feasible) with indicated radiotherapy (except for diffuse brain involvement).
• Indications for high-risk tumors (age > 40 years, subtotal resection/biopsy, IDH-wild-type, absence of ko-delece 1p/19q, KPS < 70%, tumor size > 6 cm, midline-spreading tumor, tumor localized in or near the eloquent zone, significant neurological deficit before surgery).

Due to the extent or location of the disease, there are situations where photon radiotherapy does not allow sufficient protection of healthy brain tissue (such as hippocampi) which leads to significant decline in mental function. With proton radiotherapy, the radiation dose to these structures and the toxicity of the treatment is minimized. The aim is to reduce the burden on healthy brain tissue, especially contralateral brain structures (including the hippocampus) and thus improve the quality of life in patients with a favorable long-term prognosis.

2. High-grade glioma

Proton radiotherapy is suitable for:

• Individually selected patients who will benefit from the treatment.
• Tumors located near the brainstem (without its infiltration), chiasm and lateralized (without contralateral involvement and without involvement of the corpus callosum).

However, the indication is assessed very individually – due to the extensive subclinical involvement (infiltration of brain tissue even outside the abnormal MRI finding) it is a relatively uncommon indication for other radiotherapy techniques (eg photon radiotherapy) in oligo- or asymptomatic patients with confirmed or expected unacceptable burden of surrounding healthy brain tissues.

3. Grade 1 meningioma

Proton radiotherapy is suitable for:

• In meningiomas up to 30 mm in size – radical RT with imminent neurological symptoms and proximity to risk structures and the impossibility of resection.
• For meningiomas ≥ 30 mm in size – consideration of RT with non-radical resection. The aim is the maximum protection of healthy brain tissue in patients with the expected favorable prognosis.
• Reduction of both acute and late toxicity, including the risk of secondary tumors in patients with a favorable long-term prognosis.

4. Malignant meningioma (atypical Grade II and anaplastic Grade III)

Proton radiotherapy is suitable for:

• Adjuvant radiotherapy of Grade II meningiomas after radical resection.
• Mandatory radiotherapy in non-radical resection of Grade II meningiomas and radical or non-radical resection of Grade III meningiomas.

Proton radiotherapy allows dose escalation with improved local control.

5. Chordoma and chondrosarcoma

Chordoma and chondrosarcoma, despite their different origins (chordoma originates from embryonic remnants of chorda and chondrosarcoma originates from bone-cartilaginous tissue) share a common local aggression – a high percentage of local recurrences even after macroscopically radical performance and the need to apply a high dose to ensure therapeutic effect. Adjuvant and radical radiotherapy after radical and non-radical resection.

Proton radiotherapy allows for dose escalation near healthy organs, which have a high risk of damage at the optimal dose to achieve maximum local control (brainstem, chiasma, optic nerve, inner ear, spinal cord, possibly colon, rectum, bladder in case of tumor localization in sacrum and pelvic areas).

6. Medulloblastoma in adult patients

Proton radiotherapy is used as adjuvant radiotherapy (alone or concomitant with chemotherapy). It allows progressive multiorgan dose reduction to the inner ear, heart, lungs, esophagus, stomach, lungs, pancreas, kidneys, thyroid and vertebral bodies.

An important reason for the indication of proton therapy is the reduction of both acute and late toxicity, including risks of secondary tumors (such as malignancies of the stomach, lungs, thyroid and pancreas). Because in adult patients it is not necessary to irradiate vertebral bodies, unlike in pediatric patients, there is a unique possibility of dose reduction to bone marrow located in vertebral bodies without diffuse irradiation of the torso with low doses (so called low-dose bath). The bone marrow has a significant hematopoietic function.

7. Pituitary adenoma

The reason for the indication of fractionated radiotherapy is the reduction of irradiation of the surrounding healthy brain tissue including hippocampi, thus reducing the negative impact on neurocognitive function in patients with a favorable long-term prognosis.

8. Acoustic neurinoma (vestibular schwannoma)

Fractionated radiotherapy is indicated in an effort to preserve hearing and reduce the exposure of the surrounding healthy brain tissue, including hippocampi, to reduce the negative impact on neurocognitive function and secondary malignancies in patients with a favorable long-term prognosis.

9. Rare tumors (such as multiple myeloma, craniopharyngeoma, pineoblastoma, intracranial germinal CNS tumors and others)

The reason is the reduction of both acute and late toxicity, thus reducing the risk of damage to neurocognitive functions, hearing loss, vision loss and secondary tumors. In the case of craniospinal radiotherapy, proton therapy allows for the maximum possible multiorgan dose reduction, including gastrointestinal and hematological reduction.

10. Reirradiation

Proton radiotherapy allows for the application of a sufficiently high dose to the tumor area, while reducing the volume of repeatedly exposed brain tissue. This lowers the extent of potential post-radiation changes.