world cancer report - iarc

Fig. 5.109 The immediate aftermath of a nuclear
explosion. An increased incidence of leukaemia
and some other cancer types occurred amongst
the survivors of the bombing of Hiroshima and
Nagasaki.
Leukaemia (mainly acute myeloid) may
occur in a small proportion of cancer
patients treated with chloroambucil,
cyclophosphamide, melphalan, thiotepa,
treosulphan or etoposide, as well as certain
combination chemotherapy (Medicinal
drugs, p48). Leukaemia has followed
induction of aplastic anaemia by the antibiotic,
chloramphenicol. Certain risk factors,
such as Down’s syndrome, have been identified
for childhood leukaemia, but generally
the causes of the disease are not known.
Some studies have shown a risk of childhood
leukaemia with exposure to high level
residential extremely low frequency electromagnetic
fields, but causality has not
been established [4].
Infection with the virus HTLV-I has been
established as a cause of leukaemia. This
virus is responsible for adult T-cell
leukaemia, a disease mainly observed in
tropical countries and Japan, and rarely in
the USA and Europe. In experimental animals,
particularly in mice, there are many
retroviruses which can cause a variety of
leukaemias, but such retroviruses have not
been identified in humans.
Detection
In the case of the myeloid leukaemias, the
primary manifestations result from suppression
of normal haematopoiesis. This
causes anaemia, leading to weakness,
leukopenia (decreased numbers of white
blood cells) resulting in an increased frequency
of infection, and thrombocytopenia
(decreased numbers of platelets)
Fig. 5.110 Age-specific incidence rates in the USA of leukaemia overall and of different subtypes. AML =
acute myeloid leukaemia, ALL = acute lymphoblastic leukaemia, CLL = chronic lymphocytic leukaemia,
CML = chronic myelogenous leukaemia. Note the high incidence of ALL in children.
resulting in increased risk of haemorrhage.
Patients with chronic myelogenous
leukaemia, usually adults aged 30-50,
present with slow onset of symptoms of
anaemia, weight loss and massive
enlargement of the spleen.
In the case of lymphoid malignancies, the
primary effect is on the host immune
response, with an increased susceptibility
to infection and, in the advanced stages,
interference with bone marrow function.
Children with acute lymphoblastic leukaemia
(or young adults with acute myeloid
leukaemia) may present with anaemia,
features of infection and bleeding, which
are of rapid onset. Enlargement of the
liver and spleen is common. Patients with
acute lymphoblastic leukaemia additionally
present with bone and joint pain and
multiple lymph node enlargement (lymphadenopathy).
Chronic lymphocytic leukaemia
presents with multiple lymph node
enlargement, with or without splenic
enlargement. As the disease progresses,
anaemia sets in slowly. For leukaemia generally,
diagnosis may be suspected from
examination of peripheral blood and is
confirmed by bone marrow examination.
Pathology and genetics
Leukaemias are clonal neoplastic proliferations
of immature haematopoietic
cells characterized by aberrant or arrested
differentiation. Leukaemic cells rapid-
Leukaemia
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