Pathologies that can be potentially treated with hadrontherapy
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Primary orbital tumours are a relatively rare pathology. Except for lymphoid tumours which represent the most frequent histotype of orbital tumours, other neoplasms arising from intraorbital tissues are quite rare.
Among tumours of epithelial origin, lacrimal gland tumours are one the most common, with a high tendency to infiltrate the surrounding structures- in particular the bones that delimit the orbital cavity- making conservative surgical approach difficult. The main histotypes are adenoid cystic carcinoma, mucoepidermoid carcinoma and adenocarcinoma.
Tumours of connective origin are extremely heterogeneous from a histological point of view. The most commonly described subtypes belong to the sarcoma family.
The incidence of secondary tumours is certainly higher than that of primary orbital tumours. The most frequent metastases are found in women in relation to the high incidence rate of breast cancer. Women represent 70% of patients suffering from secondary uveal metastasis due to the strong choroid tropism of breast cancer. This is followed by metastases of bronchopulmonary and prostate tumours, and metastases from melanoma, gastrointestinal and renal tumours. Metastases from other cancers, such as thyroid, testicular, pancreatic, uterine, parotid, ovarian and pleural carcinomas, are less frequent.
Ocular melanoma is the most common malignant intraocular tumours in adults. In Italy it affects about 400-500 persons per year. Although it is rare, it can be highly disabling as it impairs visual function and can give rise to distant metastases.
Causes of orbital tumours
The risk factors that lead to the development of eye tumours are not yet known and it is difficult to define an effective prevention strategy. The best preventive measure is an annual ophthalmic exam of the ocular fundus plus a timely visit should some symptoms or abnormalities appear.
Symptoms of orbital tumours
The clinical presentation of orbital tumours, whether primary or secondary, and ocular melanoma is determined by the location where the tumour appears. Therefore, symptoms vary according to the structures compromised by the malignancy.
They may appear as an increase in eye bulging, which is called exophthalmos, as changes in the eyelids, changes in the sensitivity of the orbital region accompanied or not by local pain, visual disturbances of various kinds, such as reduced visual acuity, double vision, loss of vision in one or more directions.
Given the complexity of orbital tumour symptoms, any alteration occurring at the level of the orbit, eye and visual function requires visiting a specialist.
Diagnosis of orbital tumours
A correct diagnosis involves, first of all, accurately collecting the patient's personal and family health history. A physical examination helps evaluate the anatomical region with any changes in the parts and functions of the eye.
A complete ophthalmic evaluation involves a series of specific ophthalmic tests that the specialist will define based on diagnostic hypothesis. Radiological exams indicated for the orbital region and the eye are MRI and CT scanning with contrast agents that has to be focused on the specific region or to any other regions according to the diagnosis or the diagnostic hypothesis.
Treatment of orbital tumours
Enucleation is often necessary, with the consequent visual loss and aesthetic consequences of a mutilating surgery. To date, the approach that has been generally adopted is conservative surgical plus adjuvant radiation therapy. Since this anatomical location is well known as being difficult to attack surgically, in most cases, a macroscopic resection with wide margins is not possible. Adjuvant radiation therapy is indicated to improve local control of the malignancy administering high doses that are often limited by the proximity of critical structures. Using particles to treat this location is indicated due to their intrinsic physical selectivity that makes it possible to deliver a high dose to the tumour, sparing the surrounding healthy structures and limiting functional damage where possible. In addition, tumours of connective origin, mostly belonging to the sarcoma family, are notoriously radio-resistant and can benefit from a treatment with carbon ions. In addition to dosimetry selectivity, carbon ions also show greater biological efficacy that can possibly reduce the capacity to repair cells that are resistant to the effect of other radiations.
A conservative treatment of ocular melanoma that avoids removing the eye and preserving the patient's visual function and appearance is now the treatment of choice. Proton therapy has been commonly used since the 1980s and the large number of patients treated and the consolidated results leads us to affirm that there are no differences between radiation therapy and eye enucleation in the control results. To date, patients who require enucleation are a small minority. A close collaboration with an ophthalmologist expert in ocular oncology is necessary to use proton therapy, for both the correct diagnosis and the preparation for the treatment with protons. This preparation involves a surgical step for marking the tumour, placing small clips that will allow the radiotherapist to correctly identify and radiate the tumour, and at the same time, avoid damaging healthy structures such as, in this case, the optic nerve.
Orbital tumours and ocular melanoma are currently treated at CNAO.