Aetiology

Question 1

Aetiology definition

Answer 1

The cause, set of causes, or manner of causation of a disease or condition

Question 2

What are carcinogens?

Answer 2

Long ‘latent period’ ( dependent on carcinogen, intensity, and duration of exposure) between exposure to a carcinogenic agent & the clinical appearance of the disease = Delay in establishing cause

Question 3

What are the main carcinogen groups

Answer 3

1.Chemicals
2.Radiation
3.Viruses
4.Hormonal status
5.Genetic susceptibility
6.Chronic irritation
7.Social factors
8.Iatrogenic factors

Question 4

Chemicals

Answer 4

Some are direct carcinogens

•Many cause environmental pollution
•Workers in industries are at greatest risk

•Once identified, need to eliminate the hazard
•Classic example = asbestos and mesothelioma .

All asbestos has been banned in the UK since 1999, so modern products should be asbestos-free and there are strict regulations about work that may involve asbestos exposure .

Question 5

Ultraviolet radiation

Answer 5

Significant correlation with development of Basal cell carcinoma (BCC), Squamous cell carcinoma (SCC) and malignant melanoma

•Prolonged exposure of the skin = increased risk of skin cancer
•Fair skinned = increased risk

Question 6

Ionising radiation (A)

Answer 6

a) Occupational exposure:

•Radiation dermatitis, skin cancer and leukaemia.
•Miners of radioactive ores
•Bone sarcomas
•Painters of luminous watch dials with radium

Question 7

Ionising Radiation (B)

Answer 7

b) Therapeutic application

•Irradiation for enlarged thymus gland → Thyroid cancers
•Ankylosing spondylitis → myeloid leukaemia
•Foetal irradiation → acute lymphoblastic leukaemia
•‘Mantle RT’ for Hodgkin lymphoma → breast cancer

Question 8

Ionising Radiation (c)

Answer 8

c) Nuclear explosion

•Atomic bombs (e.g. Hiroshima)

•Some immediate effects – death (due to both heat and force of the explosion as well as acute radiation exposure)
•various cancers up to 40 years later (latent period)

Question 9

Viruses

Answer 9

HIV
•HPV
•EBV
•Hepatitis viruses

Question 10

Hormonal status

Answer 10

Fluctuations in hormone levels account for higher levels of breast cancer in women than men
•Tumours known to be hormone dependent: breast, ovary, uterus, prostate

Question 11

Genetic susceptibility

Answer 11

Few cancers have a direct link genetically - breast, ovarian, melanoma.
•Kleinfelter’s syndrome (extra X chromosome) and male breast cancer

Question 12

Chronic irritation

Answer 12

Mechanical factors or infection

•Oral cancers associated with ill-fitting dentures, poor oral hygiene, jagged teeth and syphilis

•Chronic conditions: ulcerative colitis, cirrhosis of the liver, polyps

Question 13

Social factors

Answer 13

Smoking
Inactive lifestyle
Alcohol intake
Diet

Question 14

Iatrogenic factor s

Answer 14

Immunosuppressive drugs: leukaemia and lymphomas or following organ transplant

•Cytotoxic drugs e.g. alkylating agents

•Hormonal drugs e.g. stilboestrol and oestrogen

Question 15

Aetiology and NMSC

Answer 15

The major risk factor for skin cancer is exposure to ultra-violet radiation from the sun or sun-beds, especially for fair-skinned people as UV radiation induces DNA damage in keratinocytes.
•Exponential increase of BCCs in relation to UV exposure.
•In particular, the 290-320 nm wavelength UV (sunburn wavelength) is believed to play an important role in the formation ofBCC.

•It should be viewed as a hazard to children and adolescents, as about one quarter of lifetime exposure occurs before 18 years of age.

Question 16

Aetiology SCC

Answer 16

Chronic to ultra violet light exposure
Common in sun-damped skin, fair skin,
Congenital diseases, oculocutaneous albinism and xeroderma pigmentosum and pre-existing lesions like Bowen’sdisease

Question 17

What is xerodermapigmentosum

Answer 17

A rare autosomal recessive genodermatosis with a worldwide incidence of 1:250 000 live births.
•Patients have a genetic inability to repair DNA damage that has been induced by ultraviolet light.
•This manifests clinically as photosensitivity and an incidence of cSCC that is >1000 times higher than the average.

Question 18

Treatment for xeroderma pigmentosun,

Answer 18

Treatment includes protection from ultraviolet light (avoidance, protective clothing, protective glasses, face shield, and sunscreens with a high SPF (sun protection factor).

•Due to the high incidence of skin cancer linked with xeroderma pigmentosum, patients need skin cancer surveillance every three months by a consultant dermatologist.

Question 19

Other skin conditions

Answer 19

Actinic (solar) Keratosis
•Dry, scaly patches of skin caused by sun damage
•Xeroderma pigmentosum (XP)
•Rare genetic disorder with heightened sensitivity to UV radiation
•Psoriasis treatments
•A chronic, autoimmune mediated skin condition. (slight) increased cancer risk may be due to chronic inflammation rather that immunosuppressant drugs.
•Eczema treatment
•Minimal evidence

Question 20

Other risks

Answer 20

A suppressed immune system
•Taking immune-suppressive drugs following organ transplant or receiving radiation treatment can lead to increased risk of skin cancer.
•Gorlin syndrome
•Also known as nevoid basal cell carcinoma syndrome
•Past radiation exposure
•Human Papilloma virus
•Birthmarks
•Chemical exposure

Question 21

Patient/family Hilton

Answer 21

•Being diagnosed with a non-melanoma skin cancer means that you:
•have about a 10 times higher risk of a second non melanoma skin cancer
•might also be at an increased risk of developing a second primary cancer (other than skin cancer), it’s not clear why
•Most non melanoma skin cancers don’t run in families, but research has found some families seem to have a higher number than normal.
People who have a family history of melanoma have an increased risk of basal cell skin cancer (BCC).