What is melanoma?

Melanoma is a serious form of skin cancer that arises from melanocytes, the cells responsible for producing melanin, or colour in the skin. The incidence of melanoma has been increasing globally, with 132,000 cases reported annually among the adult population. While it is commonly associated with older adults, recent trends indicate a worrying increase in the incidence of melanoma among teenagers and young people. It is still very rarely seen in children.

Epidemiology and risk factors

There are three main types of skin cancers: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous melanoma (CM). Although BCC and SCC (also known as non-melanoma cancer) are the most common, melanoma is highly malignant, meaning it is more likely for the cancer to spread. Melanoma requires an early diagnosis to help prevent this spread. There are several factors that contribute to melanoma, such as lack of awareness around the dangers of ultraviolet (UV) exposure (e.g. from the sun or tanning beds), light skin colour, blonde or red hair, number of moles, and family history of melanoma.

Stages of melanoma

The stages and the general expected five-year adult survival rates for each stage are noted below. However, it is worth noting that survival rate data for the various individual stages are not yet routinely available – this is often due to inconsistencies in the data collection by governments. Most survival data also predate significant advances in melanoma therapy, including immunotherapy and targeted treatments.

• Stage 0: Refers to melanoma in situ, meaning the melanoma cells are found only in the outer layer of skin or epidermis. This stage of melanoma is unlikely to spread to other parts of the body. The expected general survival rate for Stage 0 is 100%.
• Stage I: The primary melanoma is still only in the skin and is very thin. Stage I is divided into two subgroups, IA or IB, depending on the thickness of the melanoma. The expected general survival rate for Stage I is almost 100%.
• Stage II: Stage II melanoma is thicker than Stage I, extending through the epidermis and further into the dermis, the dense inner layer of the skin. There is a higher risk of spreading to other parts of the body such as the organs. Stage II is divided into three subgroups: A, B, or C. The expected general survival rate for Stage II is between 80 to 90%.
• Stage III: This stage describes melanoma that has spread locally or through the network of tubes and tissues that runs throughout your body. Stage III is divided into four subgroups: A, B, C, or D. The expected general survival rate for Stage III varies between 30 to 90%, depending on how deeply the melanoma has gone into the skin.
• Stage IV: This final stage describes melanoma that has spread through the bloodstream to other parts of the body, such as distant locations on the skin or soft tissue, distant lymph nodes, or other organs like the lungs, liver or brain, bone, or gastrointestinal tract. With current immunotherapy and targeted treatments, the expected general survival rate for Stage IV is approximately 50%.

The most important prognostic feature for early melanoma (Stages I–III) is the thickness of the primary tumour at diagnosis, and this determines the stage of the disease. The staging categorisation helps clarify the stage of disease for patients and healthcare professionals.

Clinical presentation

Common symptoms of melanoma include a change in the size, shape, or colour of a mole or the appearance of a new growth on the skin. The ABCDE rule (Asymmetry, Border, Colour, Diameter, Evolving) can help in identifying potential melanomas.

Melanoma can present in various ways, making early detection challenging. Common signs and symptoms include:

1. Changes in existing moles: Melanoma often arises from pre-existing moles. Any changes in size, shape, colour, or texture of a mole should be evaluated by a healthcare professional.
2. New pigmented lesions: The appearance of new pigmented lesions on the skin, especially those that are asymmetrical, have irregular borders, or multiple colours, should raise suspicion for melanoma.
3. Non-healing sores: Persistent sores or ulcers that do not heal may be indicative of melanoma.
4. Itching or bleeding: Moles or lesions that itch, bleed, or become painful should be promptly evaluated.

Diagnosis: The diagnosis of melanoma involves a process of looking at a sample of the cells under a microscope. Key diagnostic steps include:

1. Clinical examination: A thorough skin examination by a skin cancer specialist is essential for identifying suspicious lesions.
2. Removal of the mole: The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue.
3. Examination: The sample sent to the pathologist confirms the diagnosis of melanoma and the stage of the disease.

Treatment: The treatment of melanoma depends on the stage of the disease.

Conclusion: Melanoma is an emerging concern among all individuals, with increasing incidence rates and significant morbidity and mortality. Early detection, prompt treatment, and preventive measures are critical in managing melanoma. Continued research and public health efforts are needed to address the unique challenges posed by melanoma and to reduce the burden of this potentially deadly disease.