SQUAMOUS CELL CARCINOMAS
Not all skin cancers are the same. There are three common types:
- Basal cell carcinoma
- Squamous cell carcinoma
How common are they?
Squamous cell carcinomas (SCCs) are more common than melanomas but less common than basal cell carcinomas. They are unusual in younger people and generally start to occur from the 40s onwards on sun damaged skin.
What are they?
They are tumours of the epidermis – the top layer of skin. They also occur in other body sites such as the mouth, throat, oesophagus, lung, bladder and genitalia. In ‘non skin’ sites they are often discovered later and are more dangerous than skin SCCs.
Who is affected?
In Australia SCCs start to appear in people in their 40s and become increasingly common as people get older. They usually occur on the most heavily sun exposed sites especially the lower lip, nose, face, upper trunk, lower arms & lower legs. The back of the hands and forearms are a particularly common site as are the scalp & ears of bald men. They are most common in people who have had a heavy lifetime UV exposure such as outdoor workers (particularly if they have a paler skin type red/blonde hair).
How dangerous are they?
SCCs are less aggressive than melanomas but much more dangerous than basal cell carcinomas (BCCs). Several hundred Australians die each year as a result of skin SCCs. They can metastasise (ie. spread to lymph glands or distant organs such as the liver or lungs). Larger, more rapidly growing SCCs are the sort most likely to metastasise. SCCs of the lips and mouth also seem to be more dangerous.
What types are there?
SCCs are classified according to how well the cancer cells are organised ‘differentiated’ when examined under the microscope. The more organised the cells the more ‘differentiated’ the cancer. A ‘well differentiated SCC’ is generally slower growing and less aggressive. They are usually pinkish or horny nodules (lumps). A ‘poorly differentiated SCC’ is faster growing and more aggressive. They are usually ulcerated, bleeding masses on the skin.
How can I tell if I have one?
Any newly appearing nodule (lump), ulcer or persistently pink/red patch on the skin should be reported to a doctor sooner than later, especially if it bleeds. SCCs appear and grow within a matter of weeks. SCCs commonly arise in pre existing solar keratoses i.e. those multiple red, crusted ‘sun spots’ on the most sun exposed skin sites in older people.
What is the treatment?
Rapid surgical excision under local anaesthetic is the treatment of choice for most SCCs. The smaller the SCC when it is excised the better the outcome. Early detection is extremely important. Radiotherapy can be used for larger, more aggressive SCCs but is not always successful.
How do I prevent them?
SCCs are very much related to UV exposure. The less UV that falls on the skin the better. This is particularly true for those who have already had a skin cancer. Don’t ever take the attitude “Well the damage is done now so there’s no point wearing sun block “. We recommend that every adult has a routine full body skin check once a year. If you have a history of skin cancers, a paler skin type or heavy sun damage to your skin, the doctor may recommend more frequent checkups.
REMEMBER any nodule (lump), ulcer or persistently pink / red patch on the skin should be reported to a doctor sooner than later, especially if it bleeds. The sooner SCCs are detected the fewer problems they will cause.
SQUAMOUS CELL CARCINOMA IN SITU or BOWEN’S DISEASE
This is best thought of as a ‘pre SCC’ where the cancer cells are confined to the epidermis (the top layer of skin) and have not yet invaded into the lower levels. They are typically slowly growing oval, red, scaling patches which may have been present for several years before they are noticed. They are especially common on the lower legs.
Untreated they can go on to develop into full blown SCCs. Because they are superficial they can usually be treated by non surgical methods. This is a good option on the lower legs of older people where surgery often involves skin grafts and can be complicated by ulcers and infections. Efudix cream (a chemotherapy agent) applied to the lesion twice a day for 6 weeks has a cure rate of 80-90% and is usually the first choice of treatment. The application of a photosensitising chemical in photodynamic therapy (PDT) can be very effective but this treatment is not yet widely available. Recurrent lesions will usually need to be surgically excised.