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Late Effects

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Overview

 

Radiation therapy (RT) induced damage:

The severity of RT related side effects depends on:

  • Total dose of RT prescribed
  • Fractionation schedule (the way the radiation treatment is split up during the course of therapy
    • Larger fraction size is a dominant factor in predicting late normal tissue toxicity (the larger the fraction size, then the more likely it is that there will be significant long term side effects7
  • Quality of the RT
    • RT was given using orthovoltage techniques many years ago.  This was low energy RT and the dose was magnified in bone.  Leading to increased risks of damage and secondary malignancy.

In ophthalmological cancers different types of radiation therapy can be used such as:

  • Implant plaque brachytherapy
  • Photon treatment (3 –D conformal therapy or IMRT
  • Proton beam RT7

Radiation therapy side effects should always be thought of in terms acute and chronic side effects. 

Acute side effects: start during the RT or immediately after it has finished and are usually rapid onset and typically reversible7.

Example:

  • Bleopharoconjunctivitis is a common acute side effect from RT
  • Due to RT exposure to the eyelids and conjunctiva when treating an orbital tumor7
  • Causes patient discomfort for a few weeks to months and then resolves completely
  • Topical hydration and silver sulfadiazine 1% cream can help decrease the discomfort and chance of infection7

Chronic or late RT induced side effects: delayed in onset and usually do not improve.  These side effects may be serious and result in legal blindness.  These include1,7:

  • Cutaneous and conjunctival telangiectasia
  • Eyelash loss
  • Cataract
  • Dry eye
  • Glaucoma
  • Retinopathy
  • Optic neuropathy
  • Diplopia

 

Chemotherapy Induced Damage:

Chemotherapy can lead to long term orbital side effects - but these are far less frequent and predictable than those associated with RT.

 

Overview of orbital late effects related to chemotherapy3and radiation therapy:

Orbital structure

Chemotherapy Late Effect

Radiation Therapy Late Effect
Eye lid

5-FU and docetaxol have been associated with stenosis of the punctum and tear drainage system.

 

Eyelid irritation is secondary to excretion of drug into tears and inflammation of the lacrimal gland:

 

Ptosis reported with long-term corticosteroid use.

Loss of eyelashes

 

Skin changes around eye:

  • Telangectasia
  • Pigmentation changes
  • Ectropion
  • Hyperkeratosis
  • Atrophy
  • Necrosis and ulceration after very high dose therapy

 

Lacrimal gland

Dry eye is associated with:

  • Cyclophosphamide
  • Ifosfamide
  • Methotrexate
  • Busulfan
 
Conjunctiva

Conjunctivitis is a commonly reported symptom after induction therapy. This is generally transient:

 

Drugs implicated include:

  • Corticosteroids
  • Cyclophosphamide
  • Retinoids
  • Ifosfamide
  • Nitrosoureas
  • Cytosine arabinoside,
  • Doxorubicin
  • Methotrexate
  • Deoxycoformycin
  • Mitomycin C3

 

Inflammation leads to:

  • Injection (chronic redness)
  • Telangectasia
  • Symblepharon
  • Subconjunctival hemorrhage
  • Keratosis
  • Ulceration

Cornea

Keratitis can develop after many different types of chemotherapy:

  • Chlorambucil
  • cyclophosphamide
  • methotrexate
  • nitrosoureas
  • 5-FU
  • deoxycoformycin21
  • Cytosine arabinoside

 

Corneal hypoesthesia associated with:

  • Vincristine
  • Vinblastine

 

Corticosteroids associated with infective keratitis and ulcers.

RT associated with:

  • Chronic epithelial defects
  • Neovascularization
  • Keratinization
  • Edema
  • Ulceration
  • Perforation

 

 

Lens

Cataracts most frequently due to corticosteroids.

 

Cataracts less commonly associated with:

  • Busulfan
  • Mitomycin C
  • Tamoxifen

Lens most radiosensitive structure in eye.

 

RT causes posterior sub-capsular cataract

Uveal tract

 

Pupil / Iris

 

 

 

 

 

Ciliary body

 

 

 

 

Choroid

Corticosteroids are associated with raised intra-ocular pressure and glaucoma.

 

Other agents associated with uveal damage:

  • Cyclophosphamide
  • Nitrosurea
  • Vincristine

 

 

Severe uveal reactions reported after intra-carotid artery chemotherapy with:

  • Cisplatin
  • Nitrogen Mustard

RT causes:

  • Iris neovascularization and glaucoma
  • Posterior synechiae (adhesions between iris and lens)
  • Iris atrophy

 

Sclera

Scleral damage from chemotherapy is very uncommon:

  • Mitomycin C used topically for ocular surface tumors may lead to scleral ulceration
  • Corticosteroids can be associated with infection (scleral damage secondary to infection)

 

The sclera is a radioresistant structure and rarely damaged by RT.

Retina

 

 

 

Macula of retina

 

 

 

 

Optic nerve

Nitrosoureas given systemically can be associated with:

  • Retinal hemorrhages, cotton wool spots and optic disc edema

Nitrosoureas given intra-arterially can be associated with:

  • Optic neuritis and atrophy

 

Cisplatin has been associated with:

  • Retinal toxicity
  • Optic neuritis
  • Presents as color blindness

 

Other drugs associated with retinopathy:

  • Carboplatin
  • Corticosteroids
  • IT Methotrexate
  • Tamoxifen (over 9 months Rx can get a crystalline retinopathy)

 

Vinca-alkaloids associated with:

  • Optic neuropathy
  • Optic atrophy
  • Cranial nerve palsies

5FU can also rarely cause the same clinical picture

 

Radiation retinopathy may occur after RT.

 

On fundoscopy, similar changes to diabetes with:

  • Micro-aneurysms
  • Hard exudates
  • Cotton wool spots
  • Optic disc swelling
  • Vascular occlusion
  • Hemorrhages
  • Neovascularization

 

 

Orbital bone/tissue

Intra-carotid carboplatin may cause severe orbital inflammation with visual loss.

 

5FU and methotrexate have both been associated with significant peri-orbital edema.

RT given to children reduces orbital growth resulting in `hypoplasia`or under-development of the orbital bone and soft tissues

 

There is an increased risk of a second malignant neoplasm many years after therapy. The risk of this is very high for patients with bilateral retinoblastoma.

 

 

 

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