A procedure called sentinel lymph node (SLN) biopsy is now recommended for cancers that are thicker than 1 millimeter. It is usually not necessary for cancers thinner than 0.75 millimeter, unless they have opened (ulcerated). Although some evidence suggests an SLN biopsy may improve survival, no clinical trials to date have proven that it improves the outlook in people with thin melanoma.
An SLN biopsy involves the following:
- A tiny amount of a tracer, either a radioactively labeled substance or a blue dye, is injected into the tumor site.
- The substance flows through the lymph system into the sentinel node, the first lymph node to which any cancer would spread in a given area.
- The sentinel lymph node and possibly one or two other nodes are removed and biopsied.
The results of the biopsy can help doctors decide whether or not to remove other lymph nodes:
- If the sentinel node and other nodes show signs of cancer, the nearby lymph nodes are removed.
- If they do not show signs of cancer, the rest of the lymph nodes will likely be cancer-free, and further surgery is not needed.
Patients with nom-melanoma skin cancers generally require no further workup.
Those with melanoma may need the following:
- Blood tests that examine the levels of the enzyme lactate dehydrogenase. Elevated levels of this enzyme suggest that the cancer has spread.
- Blood tests to assess liver function and other factors, such as anemia. These tests help determine specific sites where the cancer may appear.
- Computed tomography (CT) scans of the chest, abdomen or pelvis, which may be used to identify whether the melanoma has spread at the time of diagnosis. These scans are also used to monitor the patient after treatment.
- Positron emission tomography (PET) may also be used. PET may help find evidence that the cancer has spread elsewhere in the body. Such evidence does not always show up during a physical exam or CT scan.
Review Date: 07/04/2010
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.