Skin cancer types – what to look for.
There are three common skin cancers – basal cell carcinomas (BCC), squamous cell carcinomas, (SCC) and melanoma. BCCs and SCCs constitute the bulk of “non-melanoma skin cancer” (NMSC), of which there are around 430,000 treated each year in Australia. There are roughly 9,000 melanomas diagnosed in Australia each year, in which almost 1,000 prove to be fatal.
Basal cell carcinoma (BCC)
Basal cell carcinoma is also known as BCC or sometimes “rodent ulcer”; it is the commonest cancer in the world but very few people actually die from this cancer; when left untreated it will slowly but surely disfigure the skin like a mouse chewing away a piece of cheese. More aggressive types of BCC can travel down nerves and cartilage and enter the skull if not adequately treated; these aggressive BCCs are often the most difficult to recognise. BCC can cause significant morbidity through cosmetic disfigurement, destruction and invasion of important structures although, since they usually grow at a fairly slow rate, they can be treated easily if detected early.
Causes for BCCs
- BCCs are most commonly caused by fair skin individuals with significant exposure to the sun rays during early years of life. Other causes are rare such as certain genetic errors or carcinogen exposure (e.g. arsenic ingestion)
- There is NO evidence that the use of sunscreen prevents the development of BCC – only sun avoidance and protective clothing will be effective.
Types of BCC:
- Nodular BCC and Superficial BCC ( These 2 are most common types and are easily treatable )
- Morphoeic and Infiltrative BCCs
These are the least common BCC but are aggressive tumours and often difficult to treat. The cancer may extend silently under the skin and spread along nerves and vessels. An analogy is the visible tree stump with its hidden roots that invisibly extend over great distances below the soil surface. As they are often difficult to see, they are sometimes inadvertently treated with liquid nitrogen “freezing” which usually only delays diagnosis further.
Treatment options:
It is very important to avoid excessive sun-exposure in early life as sun-screen does not prevent development of BCCs in later life. However, BCCs are easily curable if treatment is early, depending on the type and site of the cancer. Treatment options are:
- Excision – usually the best option
- Curettage and cautery – a technique of scraping and burning the lesion, useful for superficial BCCs
- Topical creams such as Aldara for 6 weeks – only for superficial BCCs
- Photodynamic therapy with Metvix, (two treatments) – only for superficial BCCs
- Micro-graphic controlled surgery where the excised tissue is examined immediately by the surgeon to see if it is all gone – excellent technique for the more aggressive types of BCC
- Radiotherapy for some advanced cases where surgery cannot guarantee complete cure
Actinic keratosis or Sunspots
- ‘Sun-spots’ (actinic keratosis or solar keratosis) and ‘Bowen’s disease’ are technically squamous cell carcinomas but they have not yet become invasive. Only a very small percentage of sun-spots ever become invasive SCCs but it is thought that most (~60%) SCC’s do start out as a sun-spot, hence sun-spots should be treated. Sunspots feel prickly, like sand paper. They may form horns. When a sun-spot becomes an SCC, it usually stings or becomes sore and then grows fairly quickly.
Squamous cell carcinoma (SCC)
- SCC is the second commonest skin cancer and is more dangerous than BCC as it can spread to other parts of the body especially if the tumour is thick and is located on the scalp, ear or lip. They cause approximately 300 deaths each year in Australia.
- Keratoacanthoma is a rapidly growing SCC like tumour. It is benign but nevertheless very destructive.
- SCC can also occur in other non-sun bearing sites such as bowel, cervix, lungs and throat.
Causes for SCCs
The vast majority of SCCs are due to chronic exposure of fair skinned individual UV light. Other causes are smoking (particularly important for lip/mouth/tongue cancers), scars, chronic leg ulcers, organ transplant immunosuppressive drugs and infection with human papilloma virus
Treatment options:
SCCs are easily curable if treatment is early. Treatment options are:
- Excision – again, usually the best option
- Freezing with liquid nitrogen is effective foe well circumscribed single sunspots
- Topical creams such as Efudix and Aladara can be used for sun-spots
- Photodynamic therapy with Metvix, can also be used for sun-spots
- Curettage and cautery – a technique of scraping and burning the lesion, useful for superficial SCCs
- Micro-graphic controlled surgery where the excised tissue is examined immediately by the surgeon to see if it is all gone – excellent technique for the more aggressive types of SCC
- Radiotherapy for some advanced cases where surgery cannot guarantee complete cure
- Unlike BCCs sun-screen does have a role in preventing and promoting regression of SCCs and sun-spots
Melanoma
Pictures of melanoma:
Melanoma is the 3rd most common skin cancer in Australia. Around 9000 Australian are diagnosed with melanoma each year and about 1000 die from this disease each year. However, early diagnosis and treatment can greatly improve survival.
Melanoma in situ, or Level 1 melanoma, is confined to the top layer of the skin and is not as yet “invasive”. It is totally curable if completely excised. As melanoma grows in thickness the cure rate becomes greatly reduced. So it is most important that melanoma is detected as early as possible. A patient with a melanoma of less than 0.75 mm thick can expect to have 95% cure rate however, if the melanoma is 4mm thick the patient’s life expectancy on average is less than 50% at 5 years.
Risk factors for development of melanoma
- The most important risk factor in Australia is excessive exposure to natural sun light in fair skinned individuals.
- Sunscreen does not protect susceptible individuals but wearing protective clothing does.
- Other common risk factors are: large number of moles, especially irregular shaped moles, large birth marks and family history of melanoma
Types of melanoma
- Superficial spreading melanoma is most common type and most amendable to simple excision.
- Nodular melanoma is the most dangerous melanoma as they are often very thick when diagnosed
- Lentigo maligna melanoma this type is most commonly found in elderly patients usually on the face or neck
- Melanoma in situ is the earliest form of melanoma and is totally curable with complete excision.
- Acral melanoma is on the sole of the foot or on the palm of the hand – it is uncommon and often goes unnoticed
Treatment options:
It is very important to avoid excessive sun-exposure in early life and, remember sun-screen may not prevent development of melanoma so wearing protective clothing is your most important insurance against this disease.
Melanomas are curable in the majority if diagnosed and treated early. excision. The gold standard of treatment for melanoma is complete excision, with a border of normal skin included in the excision: 0.5mm margin for in situ melanoma and 1.00 – 2.00 cm for more advanced melanoma.
Benign lesions which are commonly seen and may look like melanoma
Seborrheic keratosis – very common and often called an aged-wart, senile wart or greasy wart
Solar lentigo – flat brown lesion and known as liver spot or age spots – these are related to the seborrheic keratosis
– a small blood blister-like lesion which is reddish or purple; there are usually quite a few present and can be a nuisance when nicked by the razor during shaving – they bleeds profusely!
Skin cancer detection tips
Make it a habit to examine over your skin every 3 months and check for:
- A spot that just doesn’t look like any other spot on your body – a so called “ugly duckling”
- A spot that is changing (in size, shape, color or texture)
- A spot that is tender or recurrently bleeds, get crusty or heals then breaks down again
- A spot that is elevated, firm and growing – these can be the more aggressive type of melanoma