The best survival rates of melanoma arise when the cancer is detected at its early stages, this is generally when the size of the tumours is small and treatable. After detection the prognosis of the cancer can be determined by assessing a number of histopathological factors such as the thickness of lesions, presence of ulceration and the number of metastatic lymph nodes involved. Other prognostic factors such as age, sex, anatomical location of the tumour can also be used to determine the possible progression of the cancer and the likely survival rates of the patient.
Tumour thickness and Ulceration
The most important prognosis factor in localised primary melanoma is the Breslow thickness, this measurement is used to classify how thick the melanoma lesions are. The next best indicator of survival rates is noticing if there are any ulcerations present. Lesions with increased thickness indicate a poor prognosis because it is usually the result of tumours growing rapidly and metastasising. In the absence of ulcerations, the depth of the tumours is the single most critical factor in determining survival rates. Patients with tumour thickness less than 1mm have a 5 year survival rate of 95% compared to patients with tumour thicknesses greater than 4mm who have survival rates of 76%.
The presence of ulcerations on the surface of the tumour causes a reduction in the survival rate. Ulcerations appear when an intact epidermis is not present around the tumour and is usually the result of an aggressive tumour. The presence of ulceration in tumours less than 1mm,causes a reduction in survival rates by 4% compared to non ulcerated tumour.Survival rates can reduces by upto 22% if the tumour thickness is greater than 4mm. This therefore, indicates that tumour thickness and ulceration have strong relationship with survival rates and therefore the prognosis of thin non ulcerated melanoma is excellent.
Lymph node involvement
After melanoma has reached nearby lymph nodes, the most important prognostic factor becomes the number of lymph nodes that have become tumorous. Melanomas metastasise to nearby lymph node when they start spreading from their initial site. The greater the number of tumorous nodes, the lower the survival rate. In the absence ulceration the presence of one invasive lymph node results in patients experiencing survival rates of 69% compared to patients with 4 or more tumorous lymph node experiencing survival rates of only 27%.
Other clinical factors
The prognosis of melanoma is better for younger patients, generally older patients have thicker lesions with ulcerated melanomas. Patients over the age of 35 have reduced 5 year survival rates with only 78% of these patients living 5 years or more while patients below this age have 5 year survival rates of 87%.
Females often have a better prognosis of melanoma than males. This could be the result of females having thinner lesions with less ulcerations than males.Studies have shown when metastatic melanoma is not present, females have 10 year survival rates of 86% compared to males who have survival rates of 68%.
There is a correlation between prognosis and the site of melanoma. Non metastatic melanomas located in the extremities showed 10 year survival rates of 90%. When tumours were present in areas such as the back, head, neck, and trunk there were lower levels of survival, with only 70% showing survival rates greater than 10 years.
After the cancer has metastasised to distant region, the cancer is often incurable. The prognosis is poor with median survival rates of seven and a half months. The sites where the metastatic melanoma has spread and the presence of high levels of lactate dehydrogenase are the best indicators of survival. Patients who experience lung or other visceral organ involvement with their melanoma often have reduced survival rates compared to melanomas that involve distant lymph node or subcutaneous, 1 year survival rates are 41%, 57% and 59% respectively. Other prognostic factors such as age, sex, tumour site, thickness and ulceration have a very small effect on the survival rates.
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