Brain cancers occur either primarily in the brain itself, or spread to the brain from other sites such as lungs, breasts, lymphomas, leukaemias, etc.
Since the skull provides no scope for expansion, when the cancer mass grows, it causes pressure symptoms on other parts of the brain.
Brain cancers are amongst the commonest cancers in childhood. After the leukaemias, lymphomas and the kidney cancers, they constitute the most frequently encountered cancer in childhood. Approximately 15 to 20 per cent of all brain cancers occur below the age of 15 years.
Brain cancer can arise from any of the different cells that constitute the brain substance. Each cell type may behave differently as regards to symptoms and treatment. The important types of brain cancers are:
1. Medulloblastoma
2. Glioma
In a study reported from All India Institute of Medical Sciences, New Delhi, 419 cases of cancer of the brain in children below 16 years, were seen between the years 1968-1980. There were 7 patients below 2 years of age. The highest incidence was between 10 to 15 years of age. There was a distinct male preponderance; the male to female ratio being 1.9:1. The male sex predominance was even more marked in cases of ependymoma and medulloblastoma; the ratio reaching 3:1.
Cause(s)
It is not known.
Symptoms
Symptoms depend on the:
· 1. area involved, and
· 2. the severity of pressure produced by the cancer mass on other parts of the brain.
· Epileptic fits are one of the commonest symptoms.
· Headache, nausea and vomiting are the symptoms due to the pressure exerted by the cancer mass.
· Other symptoms of loss of function of the involved part vary from case to case.
Diagnosis
Routine: History of the case; physical examination; Blood: Hb,RBC, TLC, DLC, may be normal.
Special: X-ray of the skull may reveal the cancer. CT scan of the brain indicates clearly the site and the size of the cancer, the density may indicate type of the cancer.
Brain scan shows the condensed radioactive material injected into the blood, on to the gamma camera. The cancer tissue shows as an inactive area.
Electroencephalogram (EEG) may indicate the site of the lesion, but not its nature.
The exact nature of the cancer, in the majority of the cases, can only be made out on examination of the tissue at the time of the operation.
Treatment of Glioma
It depends upon the cell-type of the cancer. It is the commonest cancer of the brain. It occurs in the young as well as the old. Some gliomas are faster-growing than the others.
Surgery: Those that are superficial can be easily removed. Before surgery is undertaken, large doses of a steroid dexamethasone (Decadron) are given, so as to drain the fluid out of the cancer mass and so to reduce its size.
The cancer and some part of the normal tissue around it, are removed. After the operation, the symptoms may increase, because of the inflammation caused by surgery, but these symptoms diminish with time.
Radiotherapy: Since it may not have been possible to remove all the cancer cells, radiotherapy is given to kill off the remaining cells. In some cases it effects a cure.
Chemotherapy: Combination of drugs used are:
· BCNU
· CCNU
· The side-effects are modest, but chemotherapy does not make the cure certain.
Treatment of Medulloblastoma
Surgery: The brain tissue involved in the cancer is removed as far as possible and feasible.
Radiation: High dose radiation is given at the site of the cancer mass, and low dosages, all over the brain and the spinal cord. It takes about 6 to 8 weeks.
Chemotherapy: The drug is given intravenously and/or through injection into the cerebrospinal fluid by piercing the coverings (theca) of the spinal cord.
As a result of the combined effect of surgery, radiation and chemotherapy, more than half the children patients live for 5 years or more. Its prognosis is better than that of glioma.
Secondary Brain Cancers
Spread of a cancer from some other part of the body to the brain is commoner than the primary cancer in the brain. The symptoms produced in the brain are the same as with primary, only that the patient is known to have a primary cancer somewhere else in the body.
Diagnosis
· Diagnosis of the primary site
· Diagnosis of the cancer in the brain
Treatment
Treatment depends on the nature of the primary cancer.
Surgery: It is only done if there is only one secondary in the brain, and the primary has been removed or managed.
Radiation: This is the line of treatment more often adopted. Surgery and radiotherapy can cure or control the disease for many years.
Early Detection
Signs & Symptoms
· Constant and increasing headache.
· Nausea and vomiting.
· Epileptic fit.
· Loss of function of a part of the body.
Investigations
· X-ray of the skull.
· CT scan of the skull.