Skin Cancer Overview and Epidemiology Flashcards
What are the two types of skin cancers?
Melanoma and Non-melanoma cancers (squamous cells and basal cell carcinomas)
What proportion of all cancers do skin cancers make up?
1/3 of all cancers
What are some reasons for the 334% increase in squamous cell carcinoma in Scotland since 1990?
Cheap air travel, more leisure time, sun-seeking behaviour, ageing population
What are some of the reasons for the impact of skin cancers?
Size of the problem
Demographic/behavioural factors
Cost of the problem (30% of hospital appointments for dermatology)
Morbidity and mortality
Lack of effective therapy in aggressive disease
What effect does melanoma have on young and middle aged adults?
Causes disproportionate mortality = average of 18.6 years of life lost per melanoma
What cells do melanomas arise from?
Melanocytes (pigment forming cells) scattered along the basal membrane
Where do melanocytes migrate from?
From the neural crest into the skin (are motile cells that move around, more likely to spread than keratinocyte cancers)
What does melanoma prognosis depend on?
Tumour depth:
Breslow thickness < 1mm = 5 year survival of 95-100%
Breslow thickness > 4mm = 5 year survival of 50%
Metastases = 5 year survival is 5%
What is the ABCDE rule?
Used to diagnose skin cancers = Asymmetry, Border, Colour, Diameter, Evolution
How is atypical mole syndrome useful?
The speed of change in the mole can be a useful red flag
How common are basal cell carcinomas?
Around 75% of skin cancers
Do basal cell carcinomas tend to spread?
No- they are locally invasive but don’t tend to metastasise
What lesions may be a basal cell carcinoma?
Slow growing lumps, non-healing ulcers, rodent ulcer (central ulceration)
What are some features of basal cell carcinomas?
Painless (often ignored), pearly or translucent, visible arborising blood vessels
What age group tends to get basal cell carcinomas?
> 40’s (but can be in 30s or 40s)
What are the different types of basal cell carcinomas?
Superficial (scaly plaque), Nodular/Nodulocystic, Infiltrative (morphoeic), Pigmented
How common are squamous cell carcinomas?
About 20% of skin cancers, account for the majority of non-melanoma cancer deaths
How do squamous cell carcinomas tend to present?
Warty or crusted lump, ulcer, fast growing, may be painful and bleed
Where do squamous cell carcinomas tend to arise?
Sun-damaged skin (lips, ears and scalp particularly high risk)
Do squamous cell carcinomas tend to spread?
Yes - may spread if neglected (5 year survival is 25%)
What are the precursor lesions of squamous cell carcinomas?
Actinic Keratosis = multiple lesions (also precursor for basal cell carcinoma)
Bowen’s disease = erythematous plaque (carcinoma in-situ)
What is the risk of metastases in squamous cell carcinoma?
3-5% (poor prognosis once metastatic)
What is a keratocanthoma?
Self-resolving squamous cell carcinoma
What are the risk factors for skin cancers?
Sun exposure, genetic predisposition, immunosuppression, other environmental carcinogens
What are some conditions that give a genetic predisposition for developing skin cancers?
DNA repair syndromes, albinism, naevoid basal cell carcinoma (Gorlin’s) syndrome, epidermolysis bullosa (especially recessive dystrophic EB)
What immunosuppressed groups are at particular risk of developing skin cancers?
Organ transplant recipients, patients with chronic inflammatory diseases (e.g vasculitis, arthritis, IBD), HIV/AIDS, haematological malignancies (e.g chronic lymphocytic leukaemia)
What are some other environmental carcinogens that can cause skin cancer?
Ionising radiation, arsenic, coal tar, trauma, chronic wounding, scarring
What causes xeroderma pigmentosum?
Defect in one of seven nucleotide excision repair (NER) genes (XPA-G)
What are some features of xeroderma pigmentosum?
Photosensitivity, skin cancers on UV exposed skin, neurological degeneration and increased risk of other cancers, 2000-10000 fold increase in skin cancer
What is oculocutaneous albinism?
Congenital absence of melanin, absence or defect of tyrosinase
What are some features of oculocutaneous albinism?
Autosomal recessive, sun sensitivity and skin cancers, lack of pigment in retina causes visual problems (photophobia, nystagmus, amblyobia)
What kind of condition is naevoid basal cell carcinoma (Gorlin’s) syndrome?
Autosomal dominant familial syndrome (1 in 57000)
What are the main features of Gorlin’s syndrome?
Early onset, multiple basal cell carcinomas, palmar pits, jaw cysts, ectopic calcification risk
What are some minor features of Gorlin’s syndrome?
Skeletal abnormalities, OFC > 97th centile, cardiac or ovarian fibroma, medulloblastoma
What causes recessive dystrophic epidermolysis bullosa (RDEB)?
Hereditary type VII collagen deficiency (also know as butterfly’s disease because the skin just crumbles off, most die of squamous cell carcinomas)
By how much does having an organ transplant increase your risk of skin cancer?
Squamous cell carcinoma increased 100-200 fold
Basal cell carcinoma increased 5-10 fold
What cause “transplant hands”?
Field cancerisation
What are some behavioural methods of skin cancer prevention?
Avoid sun at its highest (11am-3pm), use shade where possible, particular care of babies and children, avoid sun beds
What clothing helps to prevent skin cancer?
Tightly woven, loose fitting, dark, long sleeves, trousers, skirts
How should sunscreen be used to prevent skin cancer?
Broad spectrum (SPF 25+) with UVA protection, application important (twice, sufficient quantities, re-apply after swimming or towelling)
