Tumors in Children
Brain Tumors
Tumors arising in the brain come in many different forms and severities. Proton radiation therapy is used for selected patients to minimize the potentially damaging effects of radiation on the normal brain and neighboring structures. For example, using protons to treat medulloblastoma minimizes the radiation dose to the middle and inner ear. It also minimizes radiation damage to the pituitary gland and reduces the risk of damage to the optic nerves. The potential of proton radiation therapy to minimize the radiation exposure of specific structures depends greatly on tumor type and location. Therefore, proton treatment for brain tumors is highly individual. Local tumor control is expected to be at least equal to the best available results achieved using conventional radiation treatment. For selected histologies, improved outcomes are expected. An analysis of the first 27 pediatric patients treated for low-grade astrocytomas at Loma Linda University Medical Center, most of them treated for progressive, unresectable, or residual disease following subtotal resection, revealed no unexpected early or late side effects.
Orbital and Ocular Tumors in Children
The orbit contains many important organs and structures. Each of these plays an independent role in the eye's function. The lacrimal gland is involved in lubricating the eye, as are the small glands located primarily in the upper eyelid. Failure of these glands to function leads to dry-eye syndrome, which can ultimately result in complete loss of the eye. The lens also plays a crucial role. The management of cataract can be very difficult in small children. Avoiding unnecessary irradiation to the lens and the anterior chamber (to prevent glaucoma) is, therefore, highly important. Sparing a few additional millimeters of normal eye can result in crucial differences in eye function later in life.
Proton radiation therapy has been used successfully to treat orbital rhabdomyosarcomas and retinoblastomas. It is also used for tumors arising outside but in the vicinity of the orbit, where conventional radiation treatment might threaten eyesight. These tumors include sarcomas of the paranasal sinuses, parameningeal rhabdomyosarcomas, and meningiomas.
Sarcomas of the Base of Skull and Spine in Children
Proton radiation therapy has been used successfully for chordomas and chondrosarcomas of the base of skull and along the spine in adult patients. Once the safety of the treatment had been firmly established in adults, physicians began using protons with increasing frequency in pediatric patients. Currently, the experience includes a variety of osteogenic sarcomas, chondrogenic sarcomas (chordomas, chondrosarcomas), other soft tissue sarcomas (malignant fibrous, histiocytomas, synovial cell sarcoma, and others), and a variety of principally benign but locally aggressive tumors like giant cell tumors, chondroblastomas, and osteoblastomas. These tumors are treated either by proton radiation alone or in conjunction with chemotherapy. As is true of all consultations in the department of radiation medicine, a careful review is conducted to determine if additional surgery and tumor resection prior to proton radiation treatment would improve the chance of success.