Other Conditions Treated with Proton Radiation Therapy
The Loma Linda University Cancer Center is able to treat a variety of cancerous and non-cancerous conditions with proton radiation therapy. Please submit a Request Information for more details on your specific diagnosis.
Acoustic neuromas are benign tumors that involve the eighth cranial nerve and they affect our hearing. With traditional radiosurgery, more than 50 percent of patients may experience a significant loss of hearing over time. This is because the large, single doses of radiosurgery can cause tissue damage to surrounding tissue.
At our Proton Treatment Center this problem can be avoided by using fractionation of radiation treatment. This process involves the division of the total radiation dose into smaller doses, which are delivered over a longer period so as to reduce the damage to healthy cells. This not only minimizes side effects, but also makes the treatment more effective. Consequently the proton radiation therapy can achieve a high rate of tumor control while minimizing the hearing loss associated with other forms of therapy.
Chordomas and Chondrosarcomas
Chordomas and chondrosarcomas are tumors of the brain stem, spinal cord and central nervous system tissue. Proton radiation therapy has long been used to treat these tumors because it can deliver a high dose without damaging healthy brain or spinal cord tissues.
These slow-growing tumors develop from the protective linings of the brain and spinal cord, which are called meninges. Meningiomas are almost always noncancerous (benign), but they can be difficult to remove because of their location. Proton radiation therapy’s precision makes it ideal for treating these tumors.
Proton radiation therapy is used for meningiomas to deliver a high dose of radiation in a few treatments. Long-term results show that proton therapy for benign meningiomas yields excellent results with minimal side effects.
Arteriovenous Malformations (AVMs)
Arteriovenous malformations are defects of the circulatory system that are thought to arise during embryonic or fetal development or else soon after birth. AVMs are comprised of snarled tangles of arteries and veins. Proton radiation has been used successfully for many years to treat AMVs and success rates in the three years following treatment approach 80 to 85 percent for small AVMs.
Isolated Brain Metastases
These tumors occur in the pituitary gland, which is sometimes called the “master” gland of the endocrine system because it controls the functions of the other endocrine glands. Currently, microsurgery is the treatment of choice in managing this disease. Success rates with surgery in microadenomas (tumors less than 1 cm in diameter) range from 70 to 90 percent, but are much lower for larger tumors.
Pituitary adenomas typically need additional treatment after surgery to cure or prevent recurrence. Radiation with photons and charged particles, such as protons or helium ions, has been used successfully in the past. More recently, pituitary adenomas have been treated with stereotactic radiotherapeutic approaches such as single-dose radiosurgery with the "gamma knife" or linear accelerator.
At LLUMC proton beams have been used for focal irradiation of pituitary adenomas since 1990. LLUMC has pursued high-precision fractionated radiation therapy – the division of radiation doses over a period of time -- as opposed to single-dose radiosurgery. This may be a more reasonable approach in cases where the target volume is larger than 1 cm and the tumor is adjacent to vital structures.
Uveal melanomas, which are also called choroidal melanomas, are malignant tumors of the eye. Historically, these tumors have been treated by the complete removal of the eye. However, precise forms of radiation treatment such as proton beam therapy have been used to minimize the need for removal.
Protons have been used to treat uveal melanomas since the mid-1970s. Reports reveal control rates greater than 95 percent, with long-term survival consistent with survival rates for patients who have had their diseased eyes removed. Most proton patients have retained useful vision in their treated eyes. Results indicate that proton radiation is useful for medium and large tumors as well as smaller lesions.
Carcinoma of the nasopharynx is typically treated with radiation therapy alone. Local control rates for T3 lesions range from 60-85 percent. The corresponding rate is 45-70 percent for T4 tumors. Treatment-related complications can be severe because of the high doses received by critical structures surrounding the nasopharynx. These include:
- Endocrine complications secondary to hypothalamic or pituitary dysfunction
- Cranial nerve injuries
One can increase the total dose to the primary tumor while shortening the overall treatment time by using the improved properties of proton radiation treatment. Proton treatment:
- Increases local control of primary tumors
- Reduces treatment-related side effects seen with conventional radiation
- Is suitable for re-treatment of recurrent tumors
Patients treated for locally advanced oropharynx cancer usually receive combined surgery and postoperative photon radiation, or in some selected cases, radiation alone. Unfortunately, with either treatment approach a significantly high incidence of post-treatment morbidity has been reported. Severe treatment-related complications have been reported in up to 50 percent of long-term survivors. While greater doses of radiation are associated with improved levels of control, it also results in an increased complication rate. This is partly related to the large volume that is taken to a high dose using conventional radiation.
Proton treatment increases the total dose to the tumor while decreasing the dose to surrounding normal tissues. At LLUMC, protons are used in conjunction with conventional photon irradiation, with noted improvements in disease control and reduced morbidity.