How is retinoblastoma treated?

Retinoblastoma is one of the solid tumors of childhood that is most successfully treated, provided that it is diagnosed in time and treated using modern methods (brachytherapy, photocoagulation, thermochemotherapy, cryotherapy, chemotherapy). Overall survival, according to various literature data, varies from 90 to 95%. The main causes of death in the first decade of life (up to 50%) are the development of an intracranial tumor synchronously or metachronously with retinoblastoma, poorly controlled tumor metastasis beyond the central nervous system, and the development of additional malignant neoplasms.

The choice of treatment for retinoblastoma depends on the size, location, and number of lesions, the experience and capabilities of the medical center, and the risk of involvement of the second eye. Most children with unilateral tumors are diagnosed with a fairly advanced stage of the disease, often without the possibility of preserving the vision of the affected eye. This is why enucleation is often the treatment of choice. If the diagnosis is made early, alternative treatments may be used to try to preserve vision - photocoagulation, cryotherapy, or radiation.

Treatment of bilateral lesions largely depends on the extent of the disease on each side. Bilateral enucleation may be recommended if the disease is so widespread that preserving vision is out of the question. More often, only the more affected eye is removed, or, if visual function is at least somewhat preserved, enucleation is abandoned and the disease is treated conservatively. An initial course of irradiation, even in patients with advanced stages of the disease, leads to tumor regression, and vision may be partially preserved. If extraocular spread is detected, other methods are used. Spread to the orbit, brain, bone marrow indicates a poor prognosis. Such patients require chemotherapy and irradiation of the orbit or CNS.

During enucleation, it is necessary to determine the extent of tumor penetration into the optic nerve or eye membranes. The risk of metastasis depends on the extent of penetration into the optic nerve and sclera. Such patients require chemotherapy and, in some cases, orbital irradiation. An important technical point of enucleation is the removal of a sufficiently long section of the optic nerve together with the eyeball. An artificial eye can be installed as early as 6 weeks after the operation. The cosmetic defect occurs due to the fact that in small children, after the eye is removed, the normal growth of the orbit slows down. This also happens after irradiation of the orbital bones.

The advantage of cryotherapy and photocoagulation over irradiation is a lower number of complications and the possibility of repeated courses of treatment. The disadvantage of these methods is that they are ineffective in cases of large tumor mass. In addition, they can cause a scar on the retina with greater vision loss than with irradiation (special care is required when the optic nerve exit site is involved in the process).

Radiation therapy is traditionally used for large tumors involving the optic nerve, with multiple lesions. Unilateral solitary tumors with a diameter of less than 15 mm and a thickness of less than 10 mm, located at a distance of more than 3 mm from the optic nerve head, can be treated locally with radioactive plates using cobalt ( ⁶⁰ Co), iridium ( ¹⁹² Ig) or iodine ( ¹²⁵ I) without involving surrounding tissues. Retinoblastoma is classified as a radiosensitive tumor. The goal of irradiation is sufficient local control while preserving vision. Recommended doses: 40-50 Gy in fractionation mode over 4.5-6 weeks. With involvement of the optic nerve or growth into the orbit, radiation therapy is necessary for the entire orbital area at a dose of 50-54 Gy over 5-6 weeks. In the presence of trilateral retinoblastoma with pineal involvement, craniospinal irradiation is recommended.

Indications for treatment types for retinoblastoma

Procedure	Indication
Enucleation	There is no way to preserve vision
	Neovascular glaucoma
	Inability to control the tumor with conservative methods
	Inability to examine the retina after conservative therapy
Cryotherapy	Small primary or recurrent tumors in the anterior retina
	Minor relapses after irradiation
Photocoagulation	Small primary or recurrent tumors in the posterior retina
	Retinal neovascularization in radiation retinopathy

Recently, much attention has been paid to reducing possible side effects by using the lateral port irradiation method, introducing intensive chemotherapy with autotransplantation of hematopoietic stem cells. Standard chemotherapy regimens have not shown significant effectiveness, since intraocular penetration of chemotherapy drugs is reduced, and the tumor expresses membrane glycoprotein p170 and quickly becomes resistant. The drugs used in the combined treatment of retinoblastoma include vincristine, platinum drugs, cyclophosphamide, etoposide, doxorubicin. Considering that in 90% of patients the process is limited, tumor control is achieved mainly by local action.

In case of relapse and metastatic spread of the process, the prognosis is extremely unfavorable.

The survival rate of patients with retinoblastoma reaches 90%, so the main areas of therapy are associated with attempts to preserve visual function and reduce the number of complications. Early detection of carriers of the mutant RB gene and its direct replacement are promising.

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