BRAIN METASTASES

Only 10% of all cancers metastasize to the brain.

Tumors that most commonly metastasize to the brain are:

Site

Approximate % with brain metastases.

Melanoma 60
Lung 40
Breast 20
Kidney 20
Digestive tract 6

Lung cancers that most commonly develop brain metastases are small (oat) cell and adenocarcinomas.

Many other tumors can occasionally spread to the brain. Brain metastases are multiple in over 80% of cases.

Sites of metastases:

Site %
Cerebral hemispheres 80
Cerebellum 15
Pituitary 6
Brain stem 1

Clinical features:

  • Raised intra-cranial pressure (ICP)
  • Epilepsy
  • Stroke
  • Focal signs

The early features of raised ICP are early-morning headaches (worse on coughing or straining) and vomiting (often with little preceding nausea). Papilledema may be absent.

About 25% of patients present with seizures, either focal (often starting in the thumb or hand, or corner of the mouth) or generalized, however, for most patients routine prophylaxis with anti-convulsants is unnecessary, and usually need only be started after the first seizure.

About 15% of patients present with an acute stroke-like illness, due to sudden hemorrhage around a metastasis.  Unlike a cerebro-vascular accident (CVA) a continued step-wise deterioration then tends to occur. (Remember, cancer patients can also suffer an ordinary stroke.)

Focal signs include:

  •  Personality change or confusion (frontal)
  •  Disorientation (parietal)
  •  Dysphasia (parietal dominant)
  •  Hemianopsia (parietal, occipital)

Diagnosis is confirmed by CT or MRI scan.

«  Multiple cranial nerve lesions suggest carcinomatous meningitis. (see Meningeal Metastases)

Management options:

In one study median survival varied with treatment:

No treatment 1 month
Steroids 2 months
Radiotherapy 5 months
Surgery plus 6.6 months
    radiotherapy     (30% had 1-year survival)

High dose steroids (dexamethasone 16mg per day) can dramatically reduce cerebral edema and ICP and can often alleviate focal neurological signs. In lymphomas steroids can shrink the cerebral deposits themselves. 75% of patients experience short-lived symptom relief with steroids. (see Steroids)

The usual indications for radiotherapy are:

  •  Relatively fit patient
  •  No other symptomatic metastases
  •  Disease-free interval of 1 year
Cranial irradiation can be helpful for brain metastases from carcinoma of the breast, or small (oat) cell lung cancer, or lymphoma. It is usually indicated for troublesome focal symptoms such as hemiparesis or cerebellar ataxia. It is not indicated if the patient’s condition is deteriorating rapidly unless it is considered that the treatment would facilitate nursing care.

Patients who show a good response to steroids are likely to benefit from radiotherapy. Most studies show that about 75% of patients selected for radiotherapy derive worthwhile benefit, with neurological improvement from 3 to 6 months. Median survival is around 16 weeks (double the life expectancy without treatment) and 10% will live at least a year. Breast cancer patients tend to survive the longest. 

The whole brain should be irradiated because of the high probability of multiple lesions. Hair loss occurs, but few other immediate problems occur if steroids are given simultaneously. A high dose can be used (for example, 3,000cGy over 10 days) because brain cells do not divide. However, if the patient should survive 2 years or more a dementia-like syndrome can occur.

The usual indications for neurosurgical excision are:

  •  Relatively fit patient
  •  No systemic metastases
  •  Solitary deposit on CT or MRI scan
  •  Disease-free interval of 1 year

Other indications for surgery may be uncertain diagnosis, or relatively radio-resistant solitary metastasis (especially in melanoma, renal cell cancer or sarcoma).

Surgery should be followed by radiotherapy.


The author and publisher have taken precautions to ensure that the information in this book is error-free. However, readers must be guided by their own personal and professional standards of good practice in evaluating and applying recommendations made herein. The contents of this book represent the views and experience of the author, and not necessarily those of the publisher.


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