Skin cancers are one of the most commonly diagnosed cancers in Australia. These malignancies of the skin are often forms of carcinomas (cancers arising from tissues that line organs) or melanomas (cancers arising from melanocytes).
The skin is the largest organ in our bodies that protect us from injury, loss of bodily fluids and help regulate body temperature. There are three layers of the skin: epidermis (top layer), dermis (middle layer) and hypodermis (bottom layer). The epidermis is the water-resistant outer layer of the skin that acts as the body’s first line of defence. It contains squamous cells (upper layer of the epidermis), basal cells (lower layer of epidermis) and melanocytes. The dermis contains the skin’s connective tissues, as well as hair follicles, sweat glands, blood vessels, lymph nodes and nerves. The hypodermis, also known as subcutaneous tissue layer, stores fat (adipose cells), and also contains connective tissue, blood vessels and nerve cells.
Skin cancers are more common in men, and is often diagnosed over the age of 40. However, anyone can develop this disease.
Types of Skin Cancers
There are three primary forms of skin cancers, which are classified by the cells they originate from.
Basal Cell Carcinomas (BCCs)
Basal cell carcinomas (BCCs) are the most common form of skin cancer, and develop from the basal cells in the skin. Basal cells are responsible for producing new skin cells as the old ones die. BCCs are often slow growing, are rarely aggressive, and often have a good prognosis.
Squamous Cell Carcinomas (SCCs)
Squamous cell carcinomas (SCCs) are the second most common form of skin cancer, and develop from squamous cells in the skin. Squamous cells are responsible for the filtration and diffusion of substances to pass through the skin. SCCs can be aggressive, and can have a good prognosis when caught early.
Melanoma
Melanoma is a rare form of skin cancer that develops from melanocytes, which are the cells that produce pigment in the skin. While melanomas are most commonly in the skin (cutaneous melanoma), they can also develop in the eye (ocular melanoma) or in mucosal surfaces (mucosal melanoma).
For more information on melanomas, please refer to the Rare Cancers Australia Melanoma (Cutaneous) page.
Rare forms of Skin Cancer
These types of skin cancers are very rare:
Treatment
If skin cancer is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
In most cases, BCCs and SCCs rarely need staging and grading as they are often slow-growing or don’t have other high-risk features. If your skin cancer does require staging, it will be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for skin cancer may include:
- Surgery, potentially including:
- Surgical excision (minor surgical procedure to remove the cancer).
- Mohs micrographic surgery (specialised surgery that removes thin layers of cancer in stages until completely removed).
- Reconstructive surgeries – such as a skin flap or skin graft (suitable for patients who have had a large skin cancer removed).
- Curettage and electrodesiccation (cancer is scraped out with a small, sharp instrument called a curette. Low-level heat is then applied to the area to stop bleeding and kill any remaining cancer cells).
- Cryotherapy (cancer is removed with liquid nitrogen, which freezes off the cancer cells).
- Photodynamic therapy (cancer cells are damaged by light-sensitive drug, called a photosensitiser).
- Radiation therapy.
- Immunotherapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
Risk factors that may increase the likelihood of developing skin cancers include:
- Having pale or freckled skin (especially if it burns easily and doesn’t tan).
- Having red or blond hair.
- Having light-coloured eyes, such as blue or green.
- Prior exposure to ultra-violet (UV) radiation.
- Tanning/solarium usage.
- Exposure to arsenic.
- Having a weakened immune system.
- Having lots of moles, especially those that are irregularly shaped and/or uneven in colour.
- Having a family history of skin cancer.
- Having a personal history of skin cancer.
- Having certain skin conditions, such as:
- Sunspots.
- Dysplastic naevus.
- Age spots (also known as seborrheic keratoses).
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
Symptoms of skin cancers often vary by subtype.
Symptoms of Basal Cell Carcinomas
Symptoms of BCCs may include:
- Lumps on areas exposed to skin, including the head, face, neck, shoulders, lower arms and legs.
- Pearl-coloured lump.
- A pale or bright pink scaly area around the lump.
- Skin ulceration.
- Bleeding.
- Inflammation.
Symptoms of Squamous Cell Carcinomas
Symptoms of SCCs may include:
- Lumps on areas exposed to skin, including the head, face, neck, shoulders, lower arms and legs.
- Rapidly growing lump.
- Thickened, red, scaly or crusted spot.
- Bleeding.
- Inflammation.
- Tender to touch.
Symptoms of Melanoma
Cutaneous melanomas often appear as unusual moles, freckles, or spots. However, their appearances can vary greatly depending on cancer type, age of the patient and other individual factors. Generally, most types of cutaneous melanomas have characteristics that can be described by the Glasglow 7-point checklist and/or the ABCDEFG of melanoma.
For more symptoms on the symptoms of melanoma, please refer to the Rare Cancers Australia Melanoma (Cutaneous) page.
Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a melanoma, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities. More specifically, they will examine the suspicious mole, spot or freckle.
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), positron emission tomography scan (PET scan) and/or ultrasound, depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage skin cancers have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.