If you’ve been diagnosed with melanoma, you may have heard your doctor talk about the stage of the disease. But how does your doctor come to this specific diagnosis, and what do the different stages mean?
First, it’s important to know that melanoma has five stages and that doctors place – or “stage” – their diagnoses in one of these categories based on such factors as the tumor’s size, thickness, and the appearance of the skin on and around it. They also consider whether the tumor has spread to the lymph nodes or other organs in the body when staging a patient’s melanoma.
Stage 0: If a doctor diagnoses a patient’s melanoma as Stage 0**,** this means that she has found abnormalities in the melanocytes in the outer layer of the two main layers of the skin (or epidermis). Melanocytes are cells found in both the skin and the eyes that produce the skin pigment compound melanin. A designation of Stage 0 – also known as melanoma in situ – means that a physician has some concern that these abnormal cells might become cancerous at some point and spread into surrounding healthy cells.
State I: Stage I melanoma is actually broken into two separate categories, Stage IA and Stage IB.
If someone is diagnosed with Stage 1A melanoma, it means that his or her doctor has found a melanoma tumor that is no more than 1 millimeter thick and that has no break in the skin (also known as an ulceration).
But if the patient has been diagnosed with Stage IB melanoma, this means that the doctor has found a tumor that is either between 1 millimeter and 2 millimeters thick with no break in the skin, or one that is no more than 1 millimeter thick but which has an ulceration.
Stage II: Like Stage I, Stage II is broken into several categories, as well, though Stage II has three categories.
In Stage IIA, the melanoma is either between 1 millimeter and 2 millimeters thick and has an ulceration, or it is between 2 millimeters and 4 millimeters thick and does not have a break in the skin.
In Stage IIB, the tumor is either between 2 millimeters and 4 millimeters thick with a break in the skin, or it is more than 4 millimeters thick without an ulceration.
In Stage IIC, the melanoma is more than 4 millimeters thick and has a break in the skin.
Stage III: Once a melanoma has reached Stage III, doctors are less concerned with the size of a tumor or whether it has an ulceration than they are with the fact that it has spread to the lymph nodes.
If a patient is diagnosed with Stage III melanoma, it means that cancer has spread to one or more of the lymph nodes or that these infected lymph nodes may be joined or “matted” together. This stage could also mean that the cancer has been found in a lymph vessel between the starting point of the tumor and the lymph node, or that small tumors have been found on or under the skin within 2 centimeters of the original tumor.
Stage IV: If a doctor classifies a patient’s melanoma as Stage IV, this means that the cancer has spread far away from the original cancer site of the skin to other major organs in the body such as the liver, brain, bone, lung, or gastrointestinal tract.
Source: National Cancer Institute at the National Institutes of Health