world cancer report - iarc

Tumour Typical location Age at clinical manifestation Five-year survival Genetic alterations
(WHO Grade) (% of cases) (% of patients)
0-20 yrs 20-45 yrs >45 yrs
Pilocytic astrocytoma Cerebellum, optic nerve 74 20 6 >85 NF1 (neurofibro-
(Grade I) matosis cases)
Low grade diffuse Cerebral hemispheres 10 61 29 >50 p53 mutation
astrocytoma
(Grade II)
Glioblastoma Cerebral hemispheres 3 25 72 50 LOH 1p, 19q
(Grade II/III)
Ependymoma Ventricles, spinal cord 37 38 25 50 Isochromosome 17,
(Grade IV) mutations of p53,
PTCH, ß-catenin
Neuroblastoma Abdomen >95 >90 (1 yr) amplification, trisomy
17q
Table 5.16 Summary of epidemiological data on intracranial tumours.
Some studies have suggested an
increased incidence of CNS neoplasms
associated with certain occupations,
including farming, fire-fighting, metalworking
and the rubber and petrochemical
industries, and with those who work as
anatomists, pathologists and embalmers,
but most of these reports have not been
confirmed and causative agents have not
been identified. Suggestions that radiofrequency
radiation generated by mobile
phones and microwave telecommunications
may play a role in the etiology of
Fig 5.150 A large glioblastoma multiforme in the
left frontal lobe, extending into the corpus callosum
and the contralateral white matter.
266 Human cancers by organ site
malignant gliomas remain to be substantiated.
Similarly, the role of diet in brain
tumour etiology, and specifically involvement
of N-nitroso compounds (which
are potent neuro-carcinogens in rodents)
formed in nitrite-preserved food, is
unclear.
The nervous system is frequently affected
in inherited tumour syndromes, often in
association with extraneural tumours and
skin lesions (Table 5.17).
Detection
Signs and symptoms largely depend on the
location of the neoplasm and include paresis
(slight/incomplete paralysis), speech disturbances
and personality changes. Patients
with oligodendroglioma often have a long
history of epileptic seizures. Eventually,
malignant brain tumours cause life-threatening
intracranial pressure that may result in
visual disturbance and ultimately lead to
unconsciousness and respiratory arrest.
Since the brain does not contain pain receptors,
headache is only present if the tumour
infiltrates the meninges. The presence of
symptoms usually leads to a detailed neurological
examination, using techniques such
as computed tomography (CT) and magnetic
resonance imaging (MRI).
Pathology and genetics
The WHO classification of tumours of
the nervous system contains more than
50 clinico-pathological entities with a
great variation in biological behaviour,
response to therapy and clinical outcome
[4]. The most frequent ones are
listed in Table 5.16. Of all intracranial
tumours, approximately 60% are of neuroepithelial
origin (gliomas), 28% are
derived from the brain coverings
(meningiomas) and 7.5% are located in
cranial and spinal nerves. Lymphomas
and germ cell tumours account for 4%
and 1% respectively.
Astrocytic tumours
Tumours of astrocytic origin constitute
the largest proportion of gliomas. They
vary greatly in morphology, genetic profile
and clinical behaviour.
Pilocytic astrocytoma (WHO Grade I) is
the most frequent CNS neoplasm in children,
and is predominantly located in the
cerebellum and midline structures, includ-