Squamous cell carcinoma affecting the nose
(a common form of skin cancer)
is a term used to describe disease that is caused by a tumour
– a collection of abnormal cells within the body that continue
to grow and divide without control. This usually results in
the development of masses (growths or lumps), which are mainly
composed of the abnormal dividing cells.
tumours do not spread to other parts of the body and tend
not to invade other surrounding tissues - these are termed
'benign' tumours. In contrast to this, the term cancer is
used to describe 'malignant' tumours, which often do invade
surrounding normal healthy tissue, and may spread to other
sites in the body (or 'metastasise'), typically spreading
via the blood stream or lymphatic system. Because of their
more invasive nature, malignant tumours (cancers) are generally
more serious than benign tumours, often causing more serious
and extensive disease.
are many different types of cancer, and they are often classified
according to the origin of the type of abnormal cell they
contain. Thus cancers known as 'carcinomas' and 'sarcomas'
are solid tumours that arise from various different tissues,
whereas ‘leukaemias' are cancers that affect the bone marrow
where blood cells are produced and often cause large numbers
of abnormal cells to appear in the blood stream. ‘Lymphoma'
is a solid cancer caused by the growth of abnormal lymphocytes
– a type of white blood cell that can also be found in tissues
and is part of the immune system.
is often the case in human medicine, the cause of cancer in
any individual cat is often unknown, and indeed many cancers
are likely to arise for a number of different reasons. Inherited
(genetic) susceptibility to the development of certain tumours
almost certainly occurs in cats, although little is known
about this at present. During a cat's life they may potentially
be exposed to a number of different things that can trigger
abnormalities within cells that may ultimately lead to development
of cancer – this may include exposure to sunlight or to a
wide variety of different chemicals (carcinogens) – but still
in most individuals, the underlying causes and trigger for
the cancer remains unknown.
do know that some viral infections in cats can cause cancer,
and feline leukaemia virus is probably the best
of this. Fortunately this is now quite rare, but this virus
can infect the blood-producing cells of the bone marrow, and
can lead to the development of leukaemia or lymphoma. Infection
with feline immunodeficiency virus (related to human immunodeficiency
virus) also on occasions can lead to the development of cancer.
Fortunately it is easy for your vet to test for the presence
of both of these viruses.
cancer is diagnosed, a natural and common reaction is ‘What
have I done wrong?' or ‘What could I have done to have prevented
this from happening?' While these are entirely natural responses
when we first learn that
pet has cancer, it is important to remember that in the vast
majority of cases we don't know what will have led to the
development of the cancer, and therefore it would have been
impossible to prevent.
are the clinical signs of cancer?
cancers can affect any tissues in the body, the clinical signs
that cats develop are extremely diverse and there are no signs
that automatically suggest cancer is the cause of disease.
In general, cancers affect older cats more commonly than younger
many cases, cancers will grow over quite a long period of
time, and initially there may just be vague signs of disease
such as poor appetite, lack of energy and weight loss. In
other cases there may be more obvious signs such as persistent
lumps in or under the skin, changes in the eyes, unexplained
bleeding or wounds that do not heal. As the disease progresses
additional complications will usually develop that often relate
to the tissues or organs mainly affected. Although cancer
may often be one of the potential causes of a variety of different
signs (especially in older cats), it is important to remember
that many other diseases commonly cause the same signs
cancer and that, even where cancer is diagnosed, there may
well be treatment options that will enable control or management
of the disease, at least for a period of time. However, as
it is important to diagnose cancer early, it is vital to seek
veterinary advice as soon as any abnormalities are noticed.
is cancer diagnosed?
you or your vet may suspect cancer to be an underlying cause
of the clinical signs your cat is showing,
clinical signs and examination by your vet are not sufficient,
alone, to be able to diagnose the condition.
investigations in the form of radiographs (X-rays) or ultrasound
examination are often needed to identify
location and/or the extent of any tumour, but the diagnosis
of cancer can only be made by the microscopic examination
of tissues by an experienced pathologist. This will usually
necessitate a biopsy (surgical removal of a small piece of
affected tissue) by your vet, although in some cases it may
be possible to make a diagnosis from either a 'fine needle
aspirate' (a small needle is inserted into a mass to remove
or ‘suck out' a few cells that can be smeared on a slide for
examination) or a ‘needle biopsy' (where a larger needle is
inserted into a lump to remove a very small 'core' of tissue).
Occasionally other techniques are also used to obtain samples
of the suspected abnormal cells so that a diagnosis can be
made. Blood samples are a routine part of the investigation
of any suspected cancer patient – partly to detect any adverse
effects of the cancer, and partly to detect the
presence of any other disease.
some cancers, occasionally more sophisticated techniques may
be required to either make (or confirm) the
or to plan the most appropriate treatment. Computed axial
tomography (so-called 'CAT' or 'CT' scans)
magnetic resonance imaging (MRI scans) are becoming more widely
available for pets and can be very valuable, especially, for
example, in the diagnosis of brain tumours, and in assessing
the extent of tumour invasion.
cancer be treated?
a diagnosis of cancer is never good news, it is not necessarily
a ‘death sentence' for a cat. Many treatment options are available
for cancers (these are covered in more detail in Cats and
cancer 2). Not all cancers respond well to therapy and the
choice of whether or not to treat, and what to treat with,
will depend on many factors. Some forms of therapy are only
available at specialist centres, and your vet may suggest
that he or she refers you to one of these places.
many cases, appropriate treatment of cancer can result in
a significant prolongation of very good quality of
for cats. Treatments can carry side effects, but your vet
will be aware of these, and the aim is always to improve the
quality of life of affected cats, and not to cause any increased
suffering through the treatment. Generally, with careful monitoring
and assessment, significant side effects can be avoided.
is not always right to treat a cat with cancer, and the cat's
quality of life must always be the overriding concern – it
is worthwhile discussing the options available in depth with
your vet before arriving at any decision.
are the common cancers that affect cats?
of the enormous variety of cancers that can affect cats (as
with any other animal), it is impossible to list all the different
types and their common manifestations. However, some of the
most commonly encountered cancers include the following:
(malignant lymphoma, lymphosarcoma) is probably the single
most common cancer that affects cats.
is a solid tumour of a type of white blood cell (lymphocyte)
that is involved in immune responses. In addition to being
present in the blood, there are accumulations of lymphocytes
that occur elsewhere in the body – either in discrete sites
(lymph nodes or lymph 'glands') or within other tissues. Because
of the wide distribution of lymphocytes in the body, lymphoma
(malignant tumour of the cells) can occur at virtually any
site, and also commonly occurs at multiple sites. Common sites
to be affected include the lymph nodes (distributed throughout
the body), the chest cavity, the intestinal tract, the nose,
the kidneys and the nervous system. Clinical signs vary according
to the tissues that are affected. Both infection with leukaemia
virus and immunodeficiency virus can be underlying or predisposing
causes of lymphoma development.
treatment options are available for lymphoma including surgery,
drug therapy and radiation therapy. The
choice will depend on the site and form of the tumour, and
the availability of the treatment options. In
cats the response to therapy can be very good and long lasting,
although few cases are genuinely 'cured'.
cell carcinoma affecting the tongue (one of the more
common oral tumours)
cell carcinoma is a cancer of the skin. Exposure to sunlight
is one trigger-factor for this cancer and it is seen more
commonly in white cats, and cats kept in hot sunny countries.
The tumour commonly affects the nose or the ears and can initially
look like a small scratch or wound that won't heal. Spread
(metastasis) of these tumours is uncommon but local lymph
nodes are sometimes affected.
treatment of these tumours can be very successful and most
commonly involves surgical removal or radiation therapy. For
some tumours affecting the superficial layers of the skin
local radiation therapy (applied via a probe touched onto
the skin) can be very effective. The response to drug therapy
(chemotherapy) is generally not very good. For some affected
cats, an alternative to conventional surgery may be 'cryosurgery'
where the affected tissue is frozen using liquid nitrogen
applied via a special probe, although conventional surgery
and/or radiation therapy are usually preferred options.
is a cancer affecting the mammary glands that is most commonly
seen in entire female cats (although it can also be seen in
male cats and spayed female cats). The tumour commonly affects
more than one of the mammary glands, which often develop multiple
firm swellings or nodules, and the tumours commonly cause
ulceration of the skin. This tumour commonly spreads to the
local lymph nodes and can also spread to the lungs.
treatment of small tumours is likely to be much more successful
than if multiple or larger tumours are present. Treatment
is usually by surgical resection of the tumour and associated
tissues, and there may also be a role for chemotherapy in
cells are a type of cell widely distributed in the body. Mast
cell tumours commonly affect the skin, the spleen
the intestines. In the intestines, these are often aggressive
tumours that cause blockage of the intestine.
can be removed surgically, but it is usually very difficult
to remove the entire tumour and spread to lymph
liver, spleen, or the lungs is common. When mast cell tumour
affecting the spleen is diagnosed, there is often also spread
to other organs (liver, lymph nodes, bones marrow). However,
surgical removal of the spleen alone can produce good disease-free
survival times (often around 12 months) in many affected cats.
cell tumours affecting the skin can be solitary masses or
multiple nodules, and these may ulcerate. Surgical
is usually curative and some may spontaneously regress. Radiation
therapy may also be used for some of these tumours.
squamous cell carcinoma
is a cancer arising from the cells lining the mouth or throat
– it often involves the tongue, and the tumour
invades the local bone and can spread to local lymph nodes.
The tumour usually causes progressive difficulty in eating,
and there may also be intermittent or continual drooling and
possibly halitosis (a bad smell from the mouth). These tumours
can be difficult to treat but may potentially respond to surgery
or radiation therapy where appropriate.
cancers form from the fibroblasts and other supporting tissues,
most commonly arising beneath the skin.
commonly present as gradually enlarging firm masses under
the skin. The degree of malignancy of these tumours varies
– some are highly malignant with extensive local invasion
of tissues, and early metastases occurring to lymph nodes
and the lungs. Others are less aggressive and will not be
so invasive or metastasise so readily.
treatment usually involves a combination of surgery with radiation
therapy and/or chemotherapy, although the prognosis is variable.
is a cancer affecting bones. Bones in the limbs or the spine
and skull can be affected, and where the limbs are involved
the cancer often leads to weakening of the bone which may
result in it becoming fractured (broken), with severe pain
and lameness. Even without a fracture developing, most cases
of osteosarcoma will produce progressive pain and lameness.
can spread (metastasise) to local lymph nodes and to the lungs,
but this does not necessarily occur, and because of this,
surgery (where possible) may be curative in these cases. Radiation
and drug therapy may also be of value in some cases.
(lung or nose) carcinoma
number of cancers can affect the respiratory tract, but the
most common are lymphoma in the nose, or
affecting the nose or the lungs. Tumours in the nose often
cause progressive obstruction to the flow of air, and often
result in snorting/snoring noises during breathing. There
may be sneezing and discharge from the nose, and as the disease
progresses there will be difficulty in breathing. Adenocarcinoma
affecting the lung can cause difficulty in breathing, coughing,
or a mixture of the two – the cancer can sometimes spread
to the bones in the toes and cause lameness.
lung tumours, surgical removal may be possible and this may
be combined with chemotherapy, although by the time these
tumours become apparent there has often been extensive spread
within the chest. For nasal tumours, generally radiation therapy
with or without chemotherapy is likely to be the best treatment.
can affect either the small intestine or the large intestine.
They are usually quite rapidly growing tumours that often
cause disease due to partial blockage of the intestine (loss
of appetite, weight loss, vomiting and diarrhoea are the most
common signs). Metastasis to local lymph nodes is common,
and the tumours often invade the intestine quite extensively.
removal is the treatment of choice. Additional chemotherapy
is used in some cases although the efficacy of this is uncertain.
Long survival times can be achieved in some cases (with surgery
alone) even where the tumour has already spread to local lymph
and liver (bile duct) adenocarcinoma
affecting the liver and/or pancreas are fortunately not very
common in cats. These tumours can cause jaundice (due to obstruction
to the flow of bile), depression, weight loss, vomiting and
distension of the abdomen (either due to the tumour or due
to accumulation of fluid in the abdomen). The prognosis for
these tumours is very poor with little response being seen
to current treatments.
Updated November 2008