Prognosis and survival for melanoma skin cancer
A prognosis is the doctor's best estimate of how cancer will affect you and how it will respond to treatment. Survival is the percentage of people with a disease who are alive at some point in time after their diagnosis. Prognosis and survival depend on many factors.
The doctor will look at certain aspects of the cancer as well as characteristics of the person (such as their age or sex). These are called prognostic factors. The doctor will also look at predictive factors, which influence how a cancer will respond to a certain treatment and how likely it is that the cancer will come back after treatment.
Prognostic and predictive factors are often discussed together. They both play a part in deciding on a prognosis and a treatment plan just for you. Only a doctor familiar with your medical history, the type and stage and other features of the cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis and chances of survival.
The following are prognostic and predictive factors for melanoma skin cancer.
Thickness of the tumour
The thickness of the primary tumour refers to how many layers of skin it has grown into. It is an important prognostic factor because it helps predict the risk that the cancer will spread. Thicker tumours have a higher risk of spreading to other parts of the body and coming back (recurring) after treatment. The thicker the tumour, the poorer the prognosis.
Ulceration
Ulceration is when melanoma has grown through the top layer of the skin (called the epidermis) and causes an open wound. Sometimes ulcerated tumours bleed. In other cases, ulceration can only be seen when the tumour is viewed under a microscope.
An ulcerated primary tumour has a less favourable prognosis than one that isn't ulcerated. Ulceration increases the risk that the cancer will spread to other parts of the body and come back after treatment.
Mitotic rate
Mitotic rate measures how fast cancer cells are dividing and growing. It is the number of cells that divide (mitosis) in a certain amount or area of cancer tissue. An increased mitotic rate is linked with a poor prognosis.
Lymph nodes with cancer
If cancer has spread to nearby lymph nodes, the prognosis is poorer. The more lymph nodes that contain cancer, the poorer the prognosis.
Location of cancer on the skin
Having melanoma on the arms or legs (extremities) has a better prognosis than having melanoma on the central part of the body (trunk), head or neck. Melanoma on the palms of the hands or soles of the feet also has a poorer prognosis compared to other locations.
Sex
Women tend to have a better prognosis than men when diagnosed with melanoma. This may be because women more commonly develop melanomas on the arms and legs, while men more commonly develop melanomas that involve the trunk, head or neck.
We need more research and can't say at this time what the prognosis is for transgender, non-binary and gender-diverse people.
Age
People younger than 35 years of age have a greater risk of melanoma spreading to nearby lymph nodes. But, overall, people who are older have a poorer prognosis.
Growth pattern
Nodular melanoma has a poor prognosis because it grows down into the layers of the skin (vertical growth pattern) and tends to be thick when diagnosed.
Distant metastases
Melanoma has a poor prognosis when it spreads to other parts of the body (called distant metastases), such as the lung, the liver or the brain.
For metastatic melanoma, a high lactate dehydrogenase (LDH) level in the blood has a poorer prognosis than when the LDH level is normal.