‫بسم هللا الرحمن الرحیم‬
Incidence and risk factors
of non melanoma
skin cancer
dr beheshti
dermatologist
june 2015
Non-Melanoma Skin Cancer
Non-melanoma skin cancer (NMSC)
is the most common human cancer.
The term encompasses basal cell
carcinoma (BCC) and
squamous cell carcinoma (SCC) of
the skin, which are both derived
from epidermal keratinocytes.
Incidence and Epidemiology
Approximately 1.2 million cases this year.
80% Basal Cell Carcinoma (BCC)
16% Squamous Cell Carcinoma (SCC)
4% Malignant Melanoma (MM)
<1% are the extremely rare skin cancers:
Desmoplastic melanoma, eccrine porocarcinoma,
cutaneous T-Cell lymphoma (CTCL,) sebaceous
gland carcinoma, Kaposi’s sarcoma, leukemia
cutis, angiosarcoma, etc.
We will focus on the bcc & scc because you will
see these more in clinical practice.
Incidence of skin cancer
BCC:
The most common and least aggressive skin
cancer.
Slowly growing with low potential to
metastasize and/or invade underlying
structures.
Lesions can be subtle and insidious,
infiltrating large areas before they are
discovered. Huge range of potential
presentations.
Nodular basal cell carcinoma
scc
Squamous cell carcinoma
Non melanoma skin cancer
What causes basal cell
carcinoma and
squamous cell
carcinoma of the skin?
Known risk factors
Ultraviolet radiation
Fair complexion
Personal history of skin cancer
Exposure to ionizing radiation
Exposure to arsenic
Exposure to certain petroleum products
PUVA therapy
Xeroderma pigmentosum
Basal cell nevus syndrome
Weakened immune system
Precancerous skin conditions
Skin & UV Rays
D. Solar UV radiation is 95%
UVA & 5% UVB.
UVA causes tanning, aging &
skin cancer.
UVB causes burning & skin
cancer.
EPIDERMIS
DERMIS
Tanning beds emit
2-3 times more UVA than the
sun.
UVA does not produce vitamin
D
SUBCUTIS
Fitzpatrick’s Skin Phototypes
Type 1: Fair skinned. Always burn (even
short exposure time of <30 min.,) never tan.
Type 2: Fair skinned. Often burn, tans with
great difficulty.
Type 3: Some sunburn at first, but then tan
deeply.
Type 4: Never burns, tans with ease.
Types 5-6: Darker skin types which burn
only under the most extreme, prolonged
exposures.
Skin phenotype
Ultraviolet radiation
Most skin cancers are caused by exposure to the sun over a
long period of time. People who work outside, such as
farmers, have a higher risk of developing skin cancer
because they are exposed to UVR. People who live at high
altitudes or in areas with year-round, bright sunlight also
have a greater risk of developing skin cancer.
Squamous cell carcinoma (SCC) has been most strongly
linked to total lifetime sun exposure. This includes
recreational and occupational exposure, and being exposed
to UVR a lot during childhood.
Basal cell carcinoma (BCC) is most common in people with
fair complexion. It has been most strongly linked to onand-off exposure to UVR, sunburns and overexposure
during the childhood or teenage years.
Uv radiation & skin cancer
Exposure to ultraviolet radiation (UVR) is the most
important risk factor for developing skin cancer.
The 3 types of UVR are UVA, UVB and UVC.
The sun is the main source of UVR.
Indoor tanning equipment, such as tanning beds
and sun lamps, is also a source of UVR.
A tan is evidence of skin damage from exposure
to UVR. Just like the sun, indoor tanning
equipment gives off UVR that can cause
melanoma, non-melanoma skin cancer, sunburns,
premature aging and cataracts.
Sun damage to skin
Children's skin is most vulnerable to
damage. Sun exposure in childhood is the
most damaging. People who have a history
of freckling in childhood, or frequent or
severe sunburn in childhood are most at risk
of developing skin cancer as adults. (The
damage to the skin can occur many years
before a cancer actually develops.) Also,
people who have worked outdoors for much
of their life and had long-term exposure to
the sun are at risk.
Grading solar damage
Fair complexion
light-coloured skin that burns easily, freckles and doesn’t
tan,having blue, green or other light-coloured eyes,having
red or blond hair
People with a fair complexion are at a higher risk of
developing non-melanoma skin cancer than people with
other skin types.
This risk is greater because light skin has less pigment, or
melanin. Melanin is what gives your skin, hair and eyes
their colours. Experts think that it also helps protect the
skin from UVR.
People with a fair complexion who had very bad
sunburns at an early age have the highest risk for
non-melanoma skin cancers.
Risk factors
A recent Australian national household survey found the
agestandardised rate for non-melanoma skin cancer per
100,000 population was 1170; for basal cell carcinoma (BCC)
it was 884 and for squamous cell carcinoma (SCC) it was 3871
. The likelihood of having at least one non-melanoma
skin cancer by age 70 was estimated as 70% for men
and 58% for women. The New Zealand situation is
undoubtedly similar. These fi gures probably underestimate
the true incidence; nevertheless it is clear that nonmelanoma skin cancer is extremely common here
Sun damage to skin
BCC & SCC typically develops on a sunexposed area of the skin such as the head
and neck. However, they can develop on
any area of skin. The main risk factor
which damages skin and can lead to a BCC
or SCC is sun damage.
About 9 in 10 cases of BCC and SCC are
thought to be caused by sun damage.
It is the ultraviolet (UV) radiation in
the sunshine which does the damage.
Sun damage to skin
People most at risk of skin damage are
people with fair skin.
In particular, those with skin which
always burns and never tans, red or
blond hair, green or blue eyes.
Dark skinned people rarely develop
BCC or SCC, as they have more
protective melatonin in their skin
Risk of Additional Cancers
-Individuals who have had a BCC or SCC are
at increased risk for the development of
additional BCCs and SCC , compared to the
general population.
- Patients with NMSC are also at increased
risk for developing cutaneous melanoma .
-In addition, persons with a history of NMSC
are at increased risk for developing and
dying from other (nonskin cancers ).
Exposure to ionizing radiation
People who have had radiation therapy in
the past have a greater risk of developing
non-melanoma skin cancer in the treatment
area.
These second cancers can develop 15–20
years after they received radiation therapy.
Radiation exposure from nuclear fallout,
such as in Hiroshima, Japan, is linked with a
higher risk of developing non-melanoma
skin cancer.
PUVA therapy
PUVA is a common treatment for skin
conditions like psoriasis.
It uses the drug psoralen and UVA
radiation. Psoralen makes the skin
more sensitive to UVA light.
Receiving PUVA therapy for a long
period of time increases your risk of
developing squamous cell carcinoma
(SCC)
Exposure to arsenic
Exposure to arsenic increases the risk of developing nonmelanoma skin cancer.
Arsenic is a naturally occurring substance found in
rocks and soil. Arsenic and compounds that contain
arsenic are also found in certain types of wood
preservatives, pesticides and insecticides.
People who work in mining and smelting industries
can be exposed to arsenic. People who manufacture
and apply pesticides and insecticides may also be
exposed to arsenic.
The biggest risk of exposure to arsenic is through drinking
water that contains high levels of arsenic. Arsenic can get
into drinking water from natural sources or from certain
types of mining, smelting or manufacturing plants
Arsenic and tar
Chronic exposure to inorganic arsenic increases the risk of
developing Bowen’s disease (SCC in situ), BCC, and SCC .
Arsenic enhances ultraviolet carcinogenesis
. Chronic liver disease , malnutrition and smoking may
increase the risk of skin cancer in arsenic-exposed
individuals.
Contaminated drinking water is the commonest source of
arsenic exposure. Industries which may use arsenic include
glass production, and manufacture of semiconductors;
it may be found in some pesticides, and may occur as a byproduct in the smelting of copper, lead and zinc .
polycyclic aromatic hydrocarbons
Exposure to polycyclic aromatic
hydrocarbons (e.g. in shale oil,
creosote, asphalt, coal tar
products, chimney soot) may result
in an increased risk of SCC and
keratoacanthomas .
occupational
SCC in physicians using X-rays and radiation
sources is now largely of historical interest,
due to adequate controls on exposure.
There is some suggestion that ultraviolet
radiation from welding may increase the
risk of non-melanoma skin cancer .
There may also be an increased risk of SCC
and BCC from cosmic radiation exposure in
airline pilots .
Risk factors
SCC risk is associated both with
childhood sunburn, and with lifetime
sun exposure .
Outdoor work is associated with
increased risk of SCC .
Regular sunscreen use has prolonged
preventive effects on SCC, decreasing
their incidence by almost 40% .
Exposure to certain petroleum products
Occupational exposure to certain
petroleum products increases the
risk of developing non-melanoma
skin cancer.
These products include coal and
shale, industrial tar and pitch,
creosote, chimney soot and
paraffin.
Genetic Risk Factors
-Xeroderma pigmentosum
-Oculocutaneous albinism
-Epidermodysplasia verruciformis
-Dystrophic epidermolysis bullosa
-Nevoid basal cell carcinoma (NBCC)
syndrome
-Bazex syndrome and Rombo syndrome
Xeroderma pigmentosum
Xeroderma pigmentosum (XP) is a rare
inherited condition that affects the skin so it
can’t repair sun damage.
When someone has XP, their skin is more
sensitive to UVR so that it changes colour
and ages prematurely.
People with XP also have a high risk of
developing both melanoma and nonmelanoma skin cancer
Xeroderma pigmentosa
Xeroderma pigmentosa
albinism
Basal cell nevus syndrome
Basal cell nevus syndrome is also known as Gorlin
syndrome or nevoid basal cell carcinoma
syndrome. It is a rare inherited condition caused
by a mutation in a gene that suppresses tumours,
known as the patched 1 gene (PTCH1).
Basal cell nevus syndrome causes different
problems with the skin, eyes, nervous system,
endocrine glands and jawbone. People with this
syndrome also have a high risk of developing
many basal cell carcinomas.
Other risk factors Other factors
which increase the risk of
developing an SCC or BCC
include the following:
Immunosuppression
-
Organ transplantation
-Immunosuppressive drugs
-HIV infection
Weakened immune system
People with a weakened immune
system have a higher risk of developing
non-melanoma skin cancer.
The immune system can be weakened
by certain diseases.
It can also be weakened by drugs that
people need to take to suppress their
immune system following an organ
transplant
Precancerous dermatoses
Actinic keratosis
Bowen's disease
Arsenical keratosis
Cutaneous horn
Erythroplasia of Queyrat
Bowenoid papulosis of the
genitalia
Precancerous skin conditions
People who have been
diagnosed with precancerous
skin conditions have a higher
risk of developing nonmelanoma skin cancer.
These conditions include actinic
keratosis and Bowen’s disease.
Precursors to skin cancer
Actinic Keratosis (AK) Precancerous dysplasia
and hyperkeratosis of the epidermis induced by
UV radiation. A precursor to SCC.
Usually appears first on Fitz 1 or 2 patients in
their 30’s and 40’s.
About 33% of untreated AK’s progress to
SCC over a person’s lifetime.
Presents as erythematous to brown-pigmented,
gritty, rough macules and patches. Usually on
scalp, face and forearms.
Actinic keratoses
Actinic keratoses
SCC
Leukokeratosis of the lips
( Actinic cheilitis)
Squamous cell carcinoma
Squamous cell carcinoma in situ
(Bowen's disease)
SCC in situ is commonly called Bowen's
disease. The most common
presentation of SCC in situ is an
erythematous scaly patch or slightly
elevated plaque that arises within sunexposed skin of an elderly individual.
Bowen disease
Possible risk factors
The following factors have been
linked with non-melanoma skin
cancer, but there is not enough
evidence to show they are
known risk factors. Further
study is needed to clarify the
role of these factors for nonmelanoma skin cancer.
Unknown risk factors
It isn’t known whether or not the following factors
are linked with non-melanoma skin cancer. It may
be that researchers can’t show a definite link or
that studies have had different results. Further
study is needed to see if the following are risk
factors for non-melanoma skin cancer:
skin trauma
smoking
eating unmodified dairy products such as whole
milk, cheese and yogurt
selenium supplements
Alcohol
heat
The role of UV radiation from artificial sources, unlike
studies carried out in other countries, was not considered
as a predisposing factor ,because of limited availability of
equipment and also unpopularity of UV tanning beds or
UV tanning salons among members of the Iranian
population.
In contrast, a considerable proportion of our patients had
a history of radiation therapy in particular for the
treatment of tenia capitis. Application of X-ray for treating
"tenia capitis was a commonly used procedure between .
1930 and 1950; although the routinely used X-ray dose
was low (100-500 rad) but the follow-up of these patients
within decades later showed that a considerable portion
of these patients were affected by NMSC in the areas of
head and neck.
British Journal of Cancer (2015) 112,
153–156.
doi:10.1038/bjc.2014.527 www.bjcance
r.com
Published online 7 October 2014
Statin use and risk of nonmelanoma
skin cancer: a nationwide study in
Denmark
Other risk factors
Possible risk factors
Human papillomavirus (HPV)
Photosensitizing agents
Number of moles
human papillomavirus
There are several different strains of human
papillomavirus (HPV), some of which cause warts in the
genital and anal area. Infection with HPV may cause skin
cancer in this area of the body. HPV may also be a risk
factor for squamous cell cancer (SCC) of the lip.
A rare inherited genetic condition called
epidermodysplasia verruciformis makes people more
vulnerable to chronic skin infections caused by HPV. These
infections look like warts and are brown or reddish and
scaly. They appear in patches on the trunk, hands, arms,
legs and face. They can become cancerous after the age of
30.
Number of moles
Some studies have found that the
greater the number of moles, or nevi,
that a person has, the greater their
risk of developing basal cell carcinoma
(BCC).
This is especially true for women.
Photosensitizing agents
Photosensitizing agents make the skin unusually sensitive to ultraviolet
light, which may increase the risk for non-melanoma skin cancer.
People taking drugs that have photosensitizing agents can develop
sunburn or rashes after being in the sun for even short periods of time.
Some drugs that have photosensitizing agents include:
antihistamines
oral contraceptives and estrogen
nonsteroidal anti-inflammatory drugs (NSAIDs)
phenothiazines
psoralens (used in PUVA therapy for psoriasis)
sulphur drugs, such as sulphonamides and sulphonylureas
thiazide diuretics
tetracyclines
tricyclic antidepressants
chemotherapy drugs
antiparasitic drugs
oral hypoglycemics
Trauma
Trauma and scars SCC, BCC and
melanoma may arise in burn
scars .
BCC may also arise at the site of
sharp or blunt trauma, or
vaccinations
RISK FACTORS
Environmental Exposures
-UV radiation
-Tanning lamp usage
-Therapeutic UV exposure
-Photochemotherapy (PUVA) and UVB
phototherapy
-Ionizing radiation(X-rays and thermal
radiation)
Occupational risk factors
-Chemical exposures
-Human papillomavirus infection
RISK FACTORS