The prognosis for a patient with melanoma depends on a number of different characteristics of the tumor, including the type and stage of progression.
If melanoma can be diagnosed early, the prognosis is very high with a survival rate close to 100%, but the prognosis is significantly worsened if the diagnosis is not made until the later stages of progression. For this reason, it is worthwhile to encourage regular skin checks to improve methods for early intervention.
There are various factors that may affect the prognosis of an individual with melanoma.
- Breslow’s depth (tumor thickness)
- Clark level (skin structure depth)
- Type of melanoma
- Presence of ulceration
- Involvement of lymph nodes
- Presence of tumor-infiltrating lymphocytes
- Lesion location
- Satellite lesions
- Regional or distant metastasis
If the melanoma has spread to the nearby lymph nodes, the number and extent of affected nodes are important indicators of the severity of the disease. In general, local recurrences behave and grow in a similar fashion to the primary tumor. However, if they are situated at the site of wide local excision, the growth may be altered significantly.
Certain types of melanoma are associated with a better or poorer prognosis, which is usually related to the typical thickness of the type. Melanomas that are less invasive tend to have a better prognosis than deep melanomas, even if there is involvement of the lymph nodes.
The size of the metastases changes the prognosis, with micrometastases associated with a better prognosis than patients with macrometastases. The location of the metastases also has an effect, with a better prognosis for lesions in the skin or lungs and a poorer prognosis when the brain, bone and liver are involved.
Stage of Melanoma
There are several different stages of melanoma, according to the progression of disease. The following is the estimated survival rate for five years following diagnosis:
- Stage 0: 99.9% survival
- Stage I: 89-95% survival (invasive melanoma)
- Primary tumor less than 1.0 mm thick with mitosis or ulceration
- Primary tumor 1.0-2.0 mm thick, without ulceration
- Stage II: 45-79% survival (high-risk melanoma)
- Primary tumor 1.0-2.0 mm thick, with ulceration
- Primary tumor 2.0-4.0 mm thick, with or without ulceration
- Primary tumor greater than 4.0 mm thick, with or without ulceration
- Stage III: 24-70% survival (regional metastasis)
- 1-4 positive lymph node involvement
- Regional skin metastasis
- Stage IV: 7-19% survival (distant metastasis)
- Distant metastasis on skin with normal LDH
- Lung metastasis with normal LDH
- Any distant metastasis with elevated LDH
It is evident that the 5-year survival rate is lower with more advanced disease, as dictated by the diagnostic staging. In stage IV of the disease when there are distant metastases, the cancer is generally considered to be incurable and the median survival is less than once year, although some patients live for several years. In this case, the aim of treatment is to extend lifespan and improve quality of life, with the application of palliative care.