Southern Cross Medical Library

Southern Cross Medical Library

A melanoma is a serious form of skin cancer. The first symptom is a change in an existing mole or freckle, or the appearance of a new mole or freckle.

Melanoma can be successfully treated if detected early.

Melanoma is the most aggressive form of skin cancer and the third most common cancer in New Zealand.

New Zealand has one of the highest rates of melanoma in the world – each year approximately 2,700 people are diagnosed with the condition and approximately 300 die from it.

Melanomas can occur at any stage in life, though it is rare for melanomas to occur in children and teenagers. The chances of developing a melanoma increase with age.

What is melanoma?

Melanomas evolve from specialised skin cells called melanocytes. These cells produce melanin, which is the pigment that causes the skin to darken when exposed to the sun. Melanocytes are found in the outer layer of the skin. Non-cancerous growth of melanocytes produces moles and freckles.

Melanomas occur when melanocytes divide uncontrollably and form a mass of cancerous cells. While the reason this occurs is not fully understood, excessive exposure to ultraviolet (UV) radiation in sunlight and other sources is thought to be a contributing factor.

Melanomas can occur in areas of the body not necessarily exposed to UV radiation including the eye; palms of hands or soles of feet; the mouth, vulva, or vagina; and under fingernails and toenails.

Most melanomas can be cured if detected and treated early. It is important to seek medical advice if any change in a mole or freckle is noticed. If left untreated melanomas can spread to deeper layers of skin and to other areas of the body via the lymphatic system or blood. If another tumour develops as a result of the melanoma it is known as a secondary or metastatic tumour.

Risk factors

Factors that can increase the risk of developing a melanoma include:

  • increasing age
  • having fair/white skin
  • being exposed to large amounts of UV radiation e.g.: sunlight, tanning beds
  • having had one or more severe sunburns – particularly in childhood • having many moles or freckles
  • having a family history of melanoma (parent, brother/sister)
  • having had a previous melanoma
  • having a weakened immune system.

Although Māori, Pasifika, and Asian peoples have a lower risk of getting melanoma than European New Zealanders, they often have more serious melanomas. Anyone can develop melanoma regardless of their ethnicity.

Signs, symptoms, diagnosis

The first sign of a melanoma is a change in an existing mole or freckle, or the appearance of a new mole or freckle. The most common site for melanomas to occur is the back for men, and the legs for women.

If any changes or new moles or freckles are noticed, consult a doctor promptly. The doctor will examine the suspicious mole or freckle and look for any of the characteristic signs that may indicate that it is a melanoma. They will also examine the rest of the body for any other suspicious moles or freckles. When assessing a suspect freckle or mole, doctors may use one or both of the following assessment criteria.

ABCDE of melanoma:

A for Asymmetry – the mole is not symmetrical

B for Border – the edge of the mole or freckle is irregular or spreading

C for Colour – variation in colour

D for Diameter – the mole is greater than 6mm in diameter

E for Elevation or Evolving – the mole is raised, there is a change in the height of the mole, or it is enlarging or changing.

Glasgow 7-point checklist:

Change in size

Irregular shape

Irregular colour

Diameter greater than 7mm



Change in sensation.

If a mole or freckle has any of the characteristics described in either of the above assessment tools, a biopsy will be done in which the lesion is surgically removed and sent to a laboratory to be looked at under a microscope. The results will be reported to your doctor to enable an accurate diagnosis and classification (or "staging") of the melanoma if present.

Staging of melanomas

The "stage" of a melanoma will indicate if it has spread from its original site in the skin. Information required to assess the stage of a melanoma includes the depth of penetration of the tumour through the skin. This may be described in two ways. Clark's Level is an assessment of how many skin layers the tumour has invaded, while Breslow Thickness is a microscopic measurement of the thickness of the tumour.

Other information required to accurately stage a melanoma is derived from other investigations such as:

  • physical examination
  • blood tests
  • X-rays
  • scans e.g., ultrasound, CT, MRI, or PET scans.

These tests can assess whether the melanoma has spread to surrounding lymph nodes or to other parts of the body.

In New Zealand most melanoma specialists refer to the American Joint Committee of Cancer (AJCC) cutaneous melanoma staging guidelines when staging a melanoma. The stages are:

  • Stage 0 – in situ melanoma (only occurring in the top layer of the skin)
  • Stage 1 – thin melanoma: less than or equal to 2mm in thickness (or less than or equal to 1mm in thickness if ulceration is present)
  • Stage 2 – thick melanoma: greater than 2mm in thickness (or greater than 1mm in thickness if ulceration is present)
  • Stage 3 – melanoma spread to involve local lymph nodes
  • Stage 4 – secondary cancers are found elsewhere in the body. The stage of a melanoma will influence what treatment is undertaken.


If the melanoma is found early, the whole melanoma will likely be surgically removed during the initial biopsy. With early diagnosis, 90% of melanomas can be cured with simple surgery. In other cases, a second surgery may be needed so that a greater area of surrounding tissue can be removed to ensure all cancer calls are gone. It may also be necessary to biopsy or remove lymph nodes in the area. If the surgery is extensive, skin grafts to cover the removed area of skin may be required.

If the melanoma has spread to other parts of the body, other forms of treatment, or a combination of treatments, surgery, drug therapy, and/or radiation therapy, may be necessary.

Other treatment options include:

  • radiotherapy (also called radiation therapy) – the use of high-powered energy beams, such as x-rays, to destroy cancer cells
  • immunotherapy – the use of drugs that stimulate the body's immune system to fight the cancer cells
  • targeted therapy – the use of drugs that target the damaged genes or proteins of cancer cells to stop the cancer growing and spreading.
  • chemotherapy – the use of drugs to destroy cancer cells. With the development of other treatments, immunotherapy and targeted therapy, use of chemotherapy is declining.

In cases where the melanoma has spread, a team of health professionals may be involved in treatment.

This can include:

  • family doctor
  • dermatologists (skin specialists)
  • oncologists (cancer specialists)
  • plastic surgeons (specialist surgeons who reconstruct damaged areas of the body)
  • specialist cancer nurses
  • radiation therapists.

Following diagnosis and treatment, regular medical follow-ups are necessary to monitor the recovery process, and to check for recurrence or spread of the condition.


Precautions that can be taken to help prevent melanomas include:

  • avoiding going out in the sun when UV radiation levels are at their highest (between 10am and 4pm)
  • seeking shade when outside
  • wearing sun protective clothing when outdoors e.g.: wide-brimmed hats and long-sleeved tops
  • carefully applying sunscreens with a sun protection factor (SPF) of 30 or higher to exposed parts of your body before going out in the sun
  • wearing UV radiation protective sunglasses
  • never allowing your skin to burn
  • avoiding sun beds or tanning booths.

In addition, examine your skin regularly for new growths and changes in existing moles and freckles.

Further information and support

Cancer Society

The Cancer Society of New Zealand operates a phone service staffed by specialist nurses to support patients diagnosed with cancer, as well as their friends and families.

Freephone: 0800 CANCER (0800 226 237)

Email: [email protected]


Melanoma New Zealand Melanoma

New Zealand is a charitable trust devoted to melanoma issues. Their mission is to enhance awareness, education, prevention, treatment, and research of melanoma in New Zealand.

Freephone: 0800 4 MELANOMA (0800 463 526)

Email: [email protected]



Ministry of Health (2022). Historical cancer data: Historical summary 1948-2020 (Report). Wellington: New Zealand Ministry of Health. [Accessed: 12/12/22]

Ministry of Health (2020). Cancer: New registrations 2018 (Report). Wellington: New Zealand Ministry of Health. Available from: [Accessed: 12/12/22] Cancer Society (2018). Early-stage melanoma of the skin (Booklet). Wellington: Cancer Society of New Zealand.

Mayo Clinic (2022). Melanoma (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. [Accessed: 12/12/22] Oakley, A. (2022). Melanoma (Web Page). Hamilton: DermNet New Zealand. [Accessed: 12/12/22] SunSmart (2021). Skin cancer (Web Page). Wellington: Health Promotion Agency. [Accessed: 12/12/22]

Last Reviewed: September 2023

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The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross.