When you have melanoma, your doctor will determine the stage of your disease. This is a very important step. It helps your doctor plan your treatment and predict how successful your treatment will be. Melanoma stages describe the severity of the disease. The stage depends on: Whether the cancer has spread to nearby lymph nodes or organs How thick or deep it is Whether it has broken through the skin Classifying Melanoma Doctors use a system of letters and numbers to classify melanoma. T stands for tumor. This category describes how deep the cancer is, how quickly cancer cells are dividing, and whether the skin is broken. This letter gets a number from 0 to 4. Very thin melanomas have little chance of spreading. The risk increases as they become thicker. So, thicker cancers have higher numbers. Melanomas with a high number of dividing cancer cells and broken skin also have a higher stage. N stands for lymph nodes. Cancer often spreads to lymph nodes first. This category gets a number from 0 to 3. Cancers with higher numbers have more lymph node involvement. M stands for metastasized. Cancer that has metastasized has spread to other organs in the body. When melanoma spreads, it becomes harder to treat. Next, doctors combine these categories to determine the overall stage of your cancer. Stages range from 0 to 4, generally written as Roman numerals 0, I , II, III and IV. Usually, lower stage cancers have a better outlook. They are more likely to respond to treatment. People with early stage cancer are more likely to survive the disease. The Stages of Melanoma Stage 0: Melanoma involves only the top layer of skin. It has not grown deeper and doctors remove it surgically. People with stage 0 melanoma may also have radiation treatment. Sometimes a prescription cream is part of the treatment plan. Properly treated stage 0 melanomas are almost always curable. Stage I: Melanoma affects only the skin, but it is thicker. The skin may also be broken. These tumors are still fairly small and are not dividing very fast. Doctors remove stage I melanomas surgically, taking more skin for bigger tumors. Stage II: Melanoma is thicker and the cancer cells divide more quickly. The skin may also be broken. However, stage II melanomas have not spread to other organs. Doctors remove these tumors surgically, but they must cut out even more skin. Doctors will test to make sure the cancer does not affect nearby lymph nodes. Stage III: Melanoma is deep in the skin and affects nearby skin or lymph nodes. Doctors must remove stage III cancer and lymph nodes surgically. Other treatments may include medication and radiation. This is an advanced stage. Treatment may not be as effective as it is against earlier stages. Removing your lymph nodes is necessary, but may cause problems. Lymph nodes are part of your immune system. Removing them makes you more likely to get infections. Also, fluid could collect at the site of your cancer. Your body may have trouble draining this fluid, resulting in swelling. This swelling—lymphedema—could be a life-long issue. Stage IV: Melanoma goes beyond the skin and has affected the lymph nodes. The cancer may also be in other organs, such as the lungs, liver or brain. Treatment involves surgery to remove the skin tumor and lymph nodes. Sometimes doctors must also remove other organs. People with stage IV melanoma also need other treatments to prevent the cancer from spreading further and coming back. A hospital stay may be necessary in some cases. These treatments may include radiation, chemotherapy and targeted medication. High doses of these drugs may cause severe side effects, such as: Constipation Coughing Diarrhea Fatigue Infection Itching Joint pain Nausea and loss of appetite The outlook for people with stage IV melanoma is often poor. However, advancements in treatment are letting people with advanced melanoma live longer.