Hi everyone. Today I want to talk about something I hope none of you have to encounter--the sentinal lymph node biopsy. This is a procedure done by surgeons in order to identify if high risk tumors have started to spread, or metastasize, in order to determine the prognosis. I hope to shed some light on this topic so you can be educated should you have to discuss this option with your dermatologist and surgical oncologist.
"High risk tumor" is a broad term used to describe deep melanomas or any other skin cancer which has a rate of metastasis. In general, a melanoma whose depth is greater than one millimeter, or less commonly a very large and deep squamous cell carcinoma would be considered high risk tumors. About 30 or 40 years ago, patients with a large melanoma underwent a "lymph node dissection" in order to determine if the cancer had spread to the lymph nodes.
The idea behind this is the assumption that if a cancer spreads, it would first spread to the nearest lymph nodes before spreading elsewhere in the body. Unfortunately, this procedure can be painful and leave behind permanent swelling or other side effects. As a result, the "sentinal lymph node biopsy" was developed in which a dye is used to determine which lymph node would be the first node affected by a spreading cancer. So only a single or several of the closest lymph nodes would be removed under the assumption that the closest nodes would be the first place to where cancer would spread. This, of course, is much easier on the patient that the large dissection.
The power of the sentinal lymph node is that involvement of this node is associated with a poorer prognosis for patients with deeper melanomas. However, it is controversial as its usefulness has been questioned and some feel it is not a good prognostic indicator for an individual cancer. This is a topic of great debate in the world of skin cancer and the official recommendations change as more data is collected and more studies are done regarding the risk-benefit ratio of this procedure.
So who should have this procedure? This is a tough question and every patient should discuss with his/her surgeon if this procedure is appropriate for the situation. A general guideline is that a melanoma with a thickness of greater than 1 millimeter have a sentinal lymph node biopsy. The guidelines and usefulness in squamous cell carcinoma have not been clearly established but it should be discussed for any patient with a very large cancer or for a patient whose immune system is compromised (for example, a kidney transplant recipient).
The bottom line is that the jury is still out on whether the sentinal lymph node biopsy is very useful. Every situation is different so be sure to ask your dermatologist or surgeon about this procedure if you have a thick melanoma or very large squamous cell carcinoma. I hope none of you ever have to contemplate this procedure but I hope this helps shed a little light on this topic and can prompt you to discuss it with your physician.