Melanoma and other skin cancers

 

Australia has among the highest rates of skin cancer in the world. Two in three Australians will develop some form of skin cancer before the age of 70 years.

  1. Skin cancer is divided into two main types
    1. Melanoma
    2. Non-melanoma skin cancer
  2. Causes of melanoma and other skin cancers
  3. Diagnostic tools
Skin cancer is divided into two main types:

Melanoma and non-melanoma skin cancer (NMSC)

1. Melanoma

Melanoma develops in the melanocytic (pigment-producing) cells located in the epidermis. Untreated, melanoma has a high risk for metastasis.

The most common clinical subtype is superficial spreading melanoma (SSM), making up 55–60% of all melanoma. SSM is most commonly found on the head and neck (per unit area). Other common sites are the trunk in males and lower extremities in females. However, SSM can develop on any part of the body, including parts not heavily exposed to ultraviolet (UV) radiation.

In NSW in 2012:

  • There were more than 4,260 new cases of melanoma (10.1% ofall cancer diagnoses) and over 530 deaths.

  • Men over the age of 40 were more than one and a half times more likely to be diagnosed with melanoma and more than twice as likely to die from it, compared to women of similar age.

  • The lifetime risk of developing melanoma by age 85 years was one in 16.

 

2. Non melanoma skin cancer (NMSK)

The incidence of NMSC in Australia is one of the highest in the world. It is estimated that two in three Australians will be diagnosed with skin cancer by the age of 70. About 2 out of 3 NMSC are basal cell carcinomas (BCC) and the remaining are predominantly squamous cell carcinomas (SCC).

• Squamous cell carcinoma (SCC) develops from keratinocytes in the epidermis and is associated with risk of metastasis. Overall, SCC is most commonly found on the face and then on the neck, dorsa of hands and forearms. Many SCCs arise from premalignant actinic keratoses.

  • SCC can spread to other parts of the body if not treated. Lesions on the face and scalp, histologically aggressive and/or larger tumours, and tumours arising in immune-suppressed individuals have a higher risk of metastases.

  • SCC appears as a thickened, red, scaly nodule that may bleed and ulcerate over time.

  • SCC grows over a period of weeks to months.

 

• Basal cell carcinoma (BCC) also develops from keratinocytes in the epidermis. In both sexes, BCC is most commonly found on the face (the eyelid, lip and nasolabial fold), followed by ears, nose and cheek.

  • BCC is the most common and least dangerous form of skin cancer.

  • BCC appears as a well-defined lump or scaly area that is red or pearly in colour.

  • BCC may bleed or become ulcerated early on, then heal and break down again.

  • BCC usually grows relatively slowly.

  • High-risk BCC subtypes and BCCs in immune suppressed individuals tend to have higher rates of recurrence after treatment.

 

 

How can NMSC be prevented?

NMSC, including BCC, SCC and pre-cancerous sun spots (actinic or solar keratosis), are strongly related to ultraviolet (UV) radiation. The predisposition related to skin colour and ability to tan cannot be changed. However, our behaviour towards sun exposure can always be improved and, ideally, since early childhood. Some protective advices are:

  • Seek shade and avoid outdoor activities in peak sun-hours (10am to 4pm), but especially around midday;

  • Wear sun-protective clothes, covering as much skin as possible;

  • Wear a wide brim hat, that protects head, face and ears;

  • Wear sunglasses with adequate UV protection (lens categories 2, 3 and 4 – according to Australian/NZ standards);

  • Apply a thick layer of broad spectrum sunscreen (protection against both UVA and UVB rays, SPF30+ or higher, preferably 50+ in Australia) – 20 minutes before going out, reapplying regularly (every 2 hours and after swimming);

  • Always remember: there is no “safe tan”!

 

 

What is the role of nicotinamide in the prevention of NMSC?

A clinical trial conducted from 2012-2014 in Australia (ONTRAC Study) showed that taking vitamin B3 (nicotinamide) in high doses (500mg orally twice a day) can prevent NMSC (BCC and SCC). Individuals taking the nicotinamide tablets had 23% less skin cancers comparing to the ones taking placebo. The benefits were higher in participants that had multiple previous skin cancers.

It is a low-cost, safe and effective intervention that has been incorporated into standard recommendations in recent years, especially for people with a past history of multiple NMSC, but not yet available to the general population.

When prescribed nicotinamide by your doctor, beware not to use nicotinic acid tablets, which is another form of vitamin B3. This can cause headache, facial redness and low blood pressure. It is essential, also, to maintain your regular skin checks and general sun protection measures. 

 

Causes of melanoma and other skin cancers
  • Unprotected exposure to UV radiation remains the single most important lifestyle risk factor for melanoma and other skin cancers.

  • UVA and UVB radiation contribute to skin damage, premature ageing of the skin and skin cancer.

  • Melanoma and BCC are associated with the amount and pattern of sun exposure, with an intermittent pattern carrying the highest risk. UV exposure in adulthood as well as in childhood contributes to BCC and melanoma risk.

  • Premalignant actinic keratoses and SCC are associated with the total amount of sun exposure accumulated over a lifetime.

  • Other risk factors for NMSC can include exposure to some chemicals (e.g. arsenic); radiation therapy and psoralen (PUVA) treatment for psoriasis; immunosuppressive therapy; and some rare genetic conditions predisposing people to skin cancer.

 

Diagnostic tools
  • Dermoscopy uses a magnifying device that allows the visualisation of diagnostic features of skin lesions that are not seen with the naked eye. It increases diagnostic accuracy and reduces unnecessary excision of benign lesions.

  • Sequential digital dermoscopy imaging (SDDI) involves the assessment of successive dermoscopic images to allow the detection of suspicious dermoscopic change in melanomas that lack dermoscopic evidence of melanoma at a particular time.

  • Total body photography allows the detection of suspicious change and is useful in high-risk patients or patients with dysplastic naevus syndrome.

  • In vivo confocal microscopy allows non-invasive “optical biopsy” with the visualisation of the morphology and organisation of the cells in depth of the skin. It is useful for difficult diagnoses and margins (i.e. amelanotic melanoma, LM).

For more information about benign lesions, melanoma and other skin cancers, please the the links below:

 

 
 
 
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