Non-Melanoma
Skin Cancer
Definition
There are several types of skin cancer, the commonest, in
order of frequency, are basal cell carcinoma (BCC), squamous
cell carcinoma (SCC) and malignant melanoma. Malignant melanoma
is covered elsewhere. Together BCC and SCC are known as
non-melanoma skin cancer. There are some rare types of skin
cancer that are not covered here.
Under the microscope skin is divided into two layers; the
uppermost is the epidermis, the deeper layer the dermis.
Basal cell carcinoma arises from cells in the lowest layer
of the epidermis or occasionally from deep portions of hair
follicles. It accounts for about three-quarters of skin
cancer in the UK. There are several types of BCC, they are
slow growing cancers which, except in very exceptional circumstances,
do not spread. However, if left they slowly enlarge, invade
and erode the skin. This may cause an ulcer, commonly known
as a “rodent ulcer”; it is important to remember
that ulceration (a break in the surface of the skin) is
not always present. If neglected these cancers can produce
a huge amount of tissue destruction. Squamous cell carcinoma
arises from cells within the upper layers of the epidermis,
known as keratinocytes. SCC grows more rapidly than BCC;
it also may invade local tissues, however it does have the
potential to spread and a small percentage of patients will
die from the disease.
Incidence/Age/Sex
There are about 36, 000 new cases of non-melanoma skin cancer
in the UK per year. There has been a doubling of cases since
1974. Both types occur with increasing frequency with increasing
age; they occur mainly in people over 60 years. Males are
affected about 1.5 times more often than females. The incidence
of non-melanoma skin cancer is about 90 per 100,000 per
year for males and for females about 60 per 100,000 per
year. For BCC males and females are equally affected; the
overall difference between the sexes is therefore due to
differences in the incidence of SCC.
Causes/Preventions
Non-melanoma skin cancer is related to lifetime sun-exposure.
It is thought that ultra-violet rays from the sun are the
main cause of skin cancer. Skin cancer is becoming more
common and this probably reflects the amount of time people
spend in the sun undertaking outside pursuits and on holiday.
Childhood sun-exposure is important and perhaps three-quarters
of one’s lifetime exposure to ultra-violet radiation
occurs before the age of 20. Individuals with fair-skin,
blue eyes and red-hair who tend to go red and/or freckle
in the sun are most at risk of non-melanoma skin cancer.
Individuals with black or brown skin are very rarely affected.
The regular use of sun-beds, tanning booths and sun-lamps
may also increase the risk of developing skin cancer. It
is important to remember that sun-bathing is not the only
cause of over-exposure to the sun; builders, farmers, gardeners
and sportsmen all need to take care.
Other less common causes of BCC include over-exposure to
certain chemicals, e.g.. arsenic and aromatic hydrocarbons
and certain inherited conditions. Radiotherapy for treatment
of other conditions can occasionally cause BCC and SCC in
later life. SCCs may arise in long-standing, unhealed wounds;
in people taking drugs to suppress the immune system (e.g..
after kidney transplants); after chronic-exposure to chemicals
such as soot and cutting oils. SCC may also be associated
with certain rare, inherited conditions.
There are some skin problems, which if left untreated, may
become non-melanoma skin cancers. Scaly areas known as solar
keratoses may affect sun-damaged skin. These are common
in elderly individuals who have experienced significant
life-time sun-exposure. Solar keratoses have a risk of turning
into SCC; about 20% of patients with solar keratosis will
develop an SCC at some stage. If an individual has had one
skin cancer they are at increased risk of developing a second.
The best prevention for non-melanoma skin cancer is protecting
one’s self from excessive sun-exposure. The Australian
Cancer Network sun-protection advice is listed below:
1. Avoid direct exposure to sunlight during
the two hours either side of noon
2. Use sun-protective clothing when exposed
to direct sunlight for periods greater than 15 minutes
3. Use broad spectrum sunscreens with a
minimum SPF of 15 as an adjunct to sun avoidance and other
sun protective measures
4. Provide and use sun protective (e.g..
shade structures) when ever possible
5. Provide children with appropriate sun
protection for outdoor activities
6. Advise against the use of sun beds,
tanning booths and tanning lamps
Signs & Symptoms
Both BCC and SCC can appear in a variety of forms. They
can arise almost anywhere on the body but the commonest
sites are exposed areas of skin, especially on the face
and neck. SCC occurs quite commonly on the ears, hands and
legs.
A lump may be found on the skin, this may be smooth with
a pearl-like appearance. It may bleed or develop a crust.
These lumps may be white, pink and red or occasionally shades
of brown. An ulcer may form. Non-melanoma skin cancers may
be flat; they may be scaly or crusty. At times it may seem
to be trying to heal and yet never quite does. All skin
cancers get larger with time, this may mean growing out
from the skin; spreading along and into the skin and/or
invading and ulcerating the skin. Pain is unusual in non-melanoma
skin cancer, unless the cancer has grown very large and
has been neglected. A doctor should see any skin problem,
which does not settle within one month. SCC can occasionally
spread, the typical site SCC first spreads to is the lymph
glands. A painless, firm lump in the lymph nodes near the
original SCC may be found. The areas where this may happen
are the groins, arm-pits and neck.
Complications of disorder
BCC is usually cured after appropriate treatment; except
in extremely unusual situations it does not spread. However,
untreated both types of non-melanoma skin cancer can cause
extensive local tissue destruction; pain and ulceration.
Invasion of the tissues can cause damage to important nearby
structures, such as the eye and nose. SCC is also commonly
cured by appropriate treatment; however, SCC may spread
to the lymph glands and to internal structures and organs.
SCC may, in a few cases, be fatal.
Tests
A doctor may be able to tell what the problem is based upon
the story and the appearance of the skin problem. The opinion
of a specialist (usually a dermatologist or a plastic surgeon)
may be recommended. In many cases the diagnosis can be made
from the symptoms and by examining a lesion; however, in
some cases this may not be possible and the doctor may recommend
a biopsy to distinguish the various forms of skin cancer
and other non-cancerous conditions. A biopsy is a simple
procedure carried out under local anaesthetic; some or all
of a lesion may be removed for study under the microscope.
Depending on the microscopic diagnosis further treatment
may be needed.
Other tests, such as X-Rays, scans and blood tests may occasionally
be needed to assess the size of a cancer; the extent of
any local spread and, for SCC, whether the cancer has spread
around the body.
Treatment
There are several treatments for non-melanoma skin cancer,
these include: surgery, curettage and cautery, cyrotherapy,
radiotherapy and chemotherapy. A special surgical technique
known as “Mohs' surgery” is sometimes used.
Surgery
Surgery is very commonly used to treat skin cancer. In most
cases the surgery can be performed under a local anaesthetic
as an out-patient. The surgeon removes the cancer and some
surrounding, normal looking skin to try and ensure all the
cancer cells are removed. The wound will be closed up with
stitches that are removed after about one week.
For larger skin cancers, more skin may have to be removed;
in this case the wound may be too large to simply stitch
up. These larger cancers are usually dealt with by a plastic
surgeon because a skin graft or skin flap may be needed.
A skin graft may be a shaving of skin, usually taken from
the thigh (split-thickness skin graft) or a full-thickness
skin graft taken from in front of or behind the ear; the
neck; the abdomen or occasionally other sites. A split-
thickness skin donor site is like a bad graze and takes
about two week to heal up. When full-thickness grafts are
used the donor site wound can normally be stitched together.
A skin graft is usually left covered with dressing for about
5 to 7 days before checking to see how well it has healed
(“taken”). Skin grafts look very purple to start
with; but over a period of months become less noticeable
and more skin-like in colour. There is often a “dip”
in the skin when a skin graft has been used. Some wounds
are repaired using a skin flap; this means the surgeon rearranges
the skin next to where the cancer was to mend the wound
made by cutting out the cancer. The wound where the flap
was taken from can usually be stitched together. A skin
flap means a longer scar; but the skin is very similar to
that which was removed and when the scarring has settled
the result is usually very good.
Lymph Node Dissection (lymph adenectomy)
If SCC spreads to the lymph glands then the surgeon will
usually recommend removal of the lymph glands from the affected
area (neck, arm-pit or groin). The operation assesses the
degree of lymph gland spread and helps to prevent further
spread around the body. Lymph node dissection is a major
operation and is carried out under general anaesthesia.
Cautery and Curettage
This may be used for small BCCs and some precancerous conditions.
Under local anaesthetic the doctor used a spoon-shaped instrument
(“curette”) to scrape away the cancer; the base
of the wound is then “cauterised” with a hot-metal
loop, wire or forceps to stop the bleeding and to destroy
any residual cancer cells. The treatment will leave a scar,
which may be noticeable.
Cryotherapy
Cryotherapy is used to treat very small and superficial
BCCs and some precancerous conditions. It is a freezing
technique that uses liquid nitrogen or a special cold-probe
to freeze the cancerous area. The cold may be a little uncomfortable.
Afterwards a scab forms which then drops off after a few
weeks when the cancer should have cleared. Sometimes the
treatment needs to be repeated.
Mohs’ Surgery
Mohs' surgery is a specialised technique named after the
doctor who introduced the principle (Fred Mohs). Only a
few doctors in certain centres undertake this type of surgery.
It is usually used for patients with recurrent BCCs in certain
areas; in it is especially helpful if it is difficult for
the surgeon to be sure of the extent of a tumour. Mohs’
surgery is performed under local anaesthetic and involves
cutting away the cancer in stages and carefully examining
each piece under a microscope to be sure that the tumour
has all been removed. Often many pieces have to be removed
and this can take a long time. In some centres this may
be all done in one day; other centres will perform the technique
over a few days. When the tumour has all been removed the
wound created will be repaired by simple stitching, skin
graft or skin flap. If a doctor feels that Mohs’ surgery
is appropriate, then you will be referred to a specialist
centre.
Radiotherapy
Radiotherapy is an effective treatment method for small
basal cell cancers. It is useful in areas, where surgery
might be difficult or disfiguring. For small cancers the
cure rates are the same as for surgery. For SCC, surgery
is usually preferred. For large cancers, or after lymph
node dissection radiotherapy is sometimes used in addition
to surgery. Radiotherapy uses high energy rays (radiation)
to kill cancer cells; at the same time normal cells are
harmed as little as possible. The treatment is performed
by a radiographer under the supervision of a doctor (radiotherapist).
Radiotherapy is given as an out-patient and is often divided
into several doses, given over a period of one or two weeks.
Radiotherapy is not painful whilst it is being performed;
afterwards the skin may be sore. The skin will become red
for a few weeks and forms a scab. After the scabs separate
the tumour usually clears. Radiotherapy is not always suitable
for all areas of the body; some examples include the ears,
lower limbs and in sites previously treated by radiotherapy.
If radiotherapy is used in hair-bearing areas then an area
of baldness may develop at this site. Unlike surgery, radiotherapy
produces very little in the way of scarring at first; however,
in contrast to surgery, over the following years the scar
may become more noticeable.
Chemotherapy
For the treatment of skin cancer chemotherapy is usually
given in the form of a cream to be applied to the cancer
itself (topical treatment). 5 fluoro-uracil is the drug
usually used in this way. It is suitable only for small,
superficial cancers. Occasionally, for the treatment of
SCC, chemotherapy may be given into the blood (systemic
treatment). This treatment is given in hospital and is reserved
for patients with advanced skin cancer. The role of systemic
chemotherapy in the treatment of SCC has not been fully
clarified.
Outcome
For most patients with BCCs cure rates of greater than 90
- 95% should be expected. Large tumours, recurrent tumours,
certain sub-types and BCCs in certain areas have higher
rates of incomplete removal and recurrence. When BCCs recur
this is at the site of the original cancer.
For SCC the recurrence rates also vary between 5 and 10%.
However, unlike BCC, SCC may spread to the lymph glands
as well as recurring at the original site. Recurrence at
the original site is serious because this is associated
with a 30% risk of spread to other sites. Spread to other
sites is very serious; two in three patients will die of
the disease.
