Radiotherapy for Benign Diseases

Radiotherapy mainly involves treatment of patients with malignant tumors. Even with recognition of the risks of late skin injury, carcinogenesis, leukemogenesis, and genetic damage from all ionizing radiation; radiation therapy also continues to be accepted treatment for benign diseases. Before initiation, the quality of irradiation, total dose, overall time, underlying organs at risk, and shielding factors should be considered. Children should be treated with ionizing radiation only in very exceptional cases and after weighing the pros and cons of the therapy. Direct irradiation of skin areas overlying organs that are particularly prone to late effects (e.g. thyroid, eye, gonads, bone marrow and breast) should be avoided. Radiation protection techniques should be used in all instances. The depth of penetration of the x-ray beam should be chosen according to the depth of the pathologic process. Choice of beam energy usually depends on the depth of the target volume; every effort is made to spare normal underlying tissue in superficial lesions. There are a number of other benign conditions that can be treated with radiotherapy; we present a brief overview of some of the commonly encountered conditions.


INTRODUCTION
Radiation therapy is a clinical modality dealing with the use of ionizing radiations in the treatment of patients with malignant neoplasias.Treatment with ionizing radiation involves the risks of late skin damage, genetic damage and radiation-induced carcinogenesis.After weighing the pros and cons of the treatment; radiation therapy also is accepted for treatment of certain benign diseases. 1rtain factors like the quality of irradiation, total dose, overall treatment time, underlying organs at risk, and shielding factors should be taken into account before starting the treatment.Children should be treated only in very exceptional cases and after considering the benefits versus the risks of the treatment.Certain underlying organs like thyroid, eye, gonads, bone marrow, and breast are especially prone to late effects of radiation therapy and therefore direct irradiation of the skin overlying these structures should be avoided.
Radiation protection techniques to spare the adjacent normal structures/ organs should be used as and when feasible as the aim of radiation therapy is to deliver a precisely measured dose of irradiation to a defined volume with as minimal damage as possible to surrounding healthy tissue, resulting in eradication of the tumor, a high quality of life, and prolongation of survival at competitive cost.
The energy of the x-ray beam and depth of penetration are chosen according to the depth of the disease and every effort is made to spare normal underlying tissue in cases where treatment involves superficial lesions.

SKIN A. Keloids
Excessive production of fibrous tissue that extends beyond the wound, becomes hyalinized and does not regress spontaneously is a keloid.The recurrence rate after excision is very high and surgical treatment alone is not recommended. 2e preferred treatment is excision followed by a method to prevent fibroblast proliferation leading to recurrence.Although good results have been reported 4][5] Radiation therapy is usually started within 24 hours after excision; the total dose is 10 to 15 Gy in two to five fractions in one to two weeks.Most recurrences occur within one year and a minimum follow-up of two years is recommended. 6

B. Plantar Warts
Radiation treatment for plantar warts is simple, safe, and effective.The wart usually separates and falls off in three to four weeks. 7

C. Keratoacanthoma
Keratoacanthoma is a rapidly growing benign tumor that may be locally invasive.[10] Radiation therapy is recommended for recurrences after surgery or when surgery results in poor cosmesis.The doses range from 35 Gy in 15 fractions to 56 Gy in 28 fractions. 11

A. Pterygium
The treatment of pterygium is surgical, but the recurrence rate is 20% to 30% without further treatment. 12Local control is significantly improved when beta-irradiation with strontium (Sr90) plaques is administered immediately after surgery. 13The dose is 8-10 Gy in each fraction for three fractions each week.

B. Exophthalmos
The pathogenesis is believed to be an autoimmune disease in which activated T-lymphocytes invade the orbit resulting in tissue edema, lymphocytic infiltration, and marked enlargement of the extraocular muscles.Because lymphocytes and fibroblasts are sensitive to radiation, retrobulbar irradiation is a logical method of treatment.Systemic high-dose steroids are customarily used, but they must be given for long periods and have many side effects.Surgical orbital decompression can be considered when there is rapidly progressive optic neuropathy or severe proptosis.The total dose is 20 Gy to the midplane, given in 10 fractions over two weeks. 14,15

C. Orbital Pseudotumor
Radiation therapy is effective, although corticosteroids are usually administered first 4 to 6-MV photon beam is used with unilateral or bilateral temporal fields sparing the lens. 16[22]

HEMANGIOMAS A. Cutaneous Lesions
A trial of oral steroids is now the preferred treatment for skin hemangiomas requiring intervention.Radiation therapy is reserved for lesions that endanger function or life and have failed other therapies. 23The skin dose is 5 to 10 Gy per treatment. 24

B. Cavernous Hemangiomas of the Liver
Radiation therapy has been used for symptomatic and unresectable lesions.The usual doses are 10 Gy or less for children and 20 to 30 Gy in three to four weeks for adults. 25If no response is observed in four to six months, an additional 10 to 15 Gy in one to two weeks can be repeated. 26

C. Vertebral Hemangiomas
Expansion of the vertebrae, extension of the tumor into the extradural space, hemorrhage or the rare compression fracture may lead to cord compression.Surgical decompression may be required but is usually difficult because of hemorrhage.Most often only limited surgery is possible and postoperative irradiation is recommended. 27Radiation therapy without surgical decompression has produced good results.The recommended dose is 30 to 40 Gy in four to six weeks.

A. Arteriovenous malformations (AVMs)
Stereo-tactic Radio surgery delivers a single fraction of high-dose irradiation to a small volume leading to sclerosis of the AVM and prevents hemorrhage.[30][31]

B. Other benign brain tumours treated with radiation therapy
Meningioma -It arises from the arachonoid meninges of the brain and grow at a slow rate. 328][39][40] Radiation dose is 50-54Gy in 25-30fractions over five to six weeks.
Pituitary Adenoma -Radiotherapy is indicated if surgical resection is not possible or if hormone level remains elevated following surgery.Dose of radiation is 45 to 50Gy over five to six weeks.
Craniopharyngioma -It arise in the sellar region from remnants of rathke's pouch.External beam radiotherapy will be treatment of choice for patients with residual disease following surgery who are at high risk for progressive disease. 41,42[45]

SOFT TISSUES A. Desmoid Tumors
Also known as aggressive fibromatosis, are low-grade, locally invasive, nonmetastasizing tumors.These tumors are deeply infiltrative, nonencapsulated and merge into the surrounding muscle, resulting in positive margins after resection.Surgical resection is the treatment of choice, but local recurrence can occur in 10% to 100% depending on the extent of the surgical resection.Recurrences are usually effectively salvaged with further surgical resection or postoperative irradiation. 46If the lesion is inoperable because of location or infiltration of vital structures, surgery is not recommended and radiation therapy is effective.The recommended dose is 50 to 60 Gy in six to seven weeks at 1.8 to 2 Gy per fraction.

B. Peyronie's Disease
It is painful angulation of the erect penis.Although the disease resolves spontaneously over time, treatment with radiation is effective and hastens regression of symptoms, especially pain.Local corticosteroid injections, systemic corticosteroids, procarbazine, or surgery are also effective in relieving symptoms to varying extent.Effective doses range from 5 Gy in one fraction (which may be repeated in one month), to 3 Gy daily for six or seven fractions. 47

BONE
A. Ameloblastoma Ameloblastomas usually occur in the jaw, and rarely metastasize.Treatment is usually by curettage, but recurrence is common.Many patients have tumors that cannot be completely excised or may be inoperable.These lesions respond well to irradiation, and doses of 50 to 60 Gy in five to six weeks produce complete regression. 48Patients should be monitored closely, because tumor regression after irradiation proceeds slowly and late metastases may occur.

B. Aneurysmal Bone Cysts
Treatment is primarily surgical.Recurrence rates after curettage only are as high as 30% to 60%.Radiation therapy is reserved for patients whose lesions are surgically inaccessible, difficult to curette properly, or continue to grow or repeatedly recur.Cysts of the spine and pelvis are especially suitable for irradiation. 49The usual recommended doses are in the range of 12 to 32 Gy at 2 Gy per fraction over two to three weeks.

A. Gynecomastia
Gynecomastia may be seen in: patients receiving estrogens or flutamide, patients undergoing orchiectomy, being treated with luteinizing hormone-releasing hormone (LHRH) agonists, and in those receiving a combination of flutamide and LHRH agonists. 50In patients treated with estrogen, breast irradiation given before administration of estrogen is effective in preventing gynecomastia; irradiation is not effective if estrogen is given first.9 Gy is given as a single dose or 4 to 5 Gy daily for three treatments. 51In addition to prophylactic treatment, radiation can be given for painful gynecomastia after diethylstilbestrol therapy with 20 Gy in 5 fractions or 40 Gy in 20 fractions. 52ain relief is obtained after two weeks to 14 months, with an average of 3.6 months.

B. Ovarian Castration
Pelvic irradiation is used to induce ovarian ablation.The recommended dose is 20 Gy in 5 to 10 fractions. 53tal Lymphoid Irradiation in the Management of Autoimmune Diseases and Organ Transplantation Total lymphoid irradiation (TLI), is a curative form of treatment for early-stage Hodgkin's disease.TLI, usually in conjunction with other immunosuppressive therapies, promotes transplantation tolerance for bone marrow, skin, heart, and kidney grafts and decreases pharmacological immunosuppression after TLI.54 Radiation is given to mantle and inverted-Y/spleen fields concurrently, using 0.8-Gy fractions, two fractions per week, to a maximum total dose of 8 Gy.

CONCLUSION
In addition to treatment of malignant diseases, radiation therapy can also be used for successful treatment of benign or non-malignant conditions either primarily or following surgery or when other modalities fail.