Is lymph node biopsy necessary for thin melanomas with risk factors for recurrence?

This study examined whether lymph node biopsy is beneficial for determining prognosis in patients with thin melanomas and at least one risk factor for recurrence.

Staging for melanoma (a determination of how advanced the disease is in a particular patient) includes measures of multiple factors, such as Breslow thickness (a measure of how deep a melanoma reaches into the skin layers), ulceration (the skin over the melanoma breaking down), and sentinel lymph node metastasis, or the spread of tumor cells to the nearest lymph nodes.

Melanomas with a small Breslow thickness have a low risk of recurrence, and these patients rarely undergo lymph node biopsies to determine if the cancer has already spread. However, patients with other risk factors, such as ulceration, younger age, or rapid tumor cell growth (mitosis), may benefit from measuring lymph node activity in order to determine prognosis (disease outlook).

The current study examined the benefit of sentinel lymph node biopsy in patients with thin primary melanomas and at least one risk factor for recurrence.

210 patients with thin melanomas (Breslow thickness less than 1 mm) and at least one additional risk factor for recurrence were included in this study. Risk factors included age younger than 40, ulceration, an increased mitosis rate, regression (when the original tumor cells are destroyed by the immune system, an indication that tumor cells have already spread to other areas), and a Clark level of 4 (a second measure of the deepness of a melanoma). All patients underwent a sentinel lymph node biopsy, and were followed for an average of 46.7 months.

In the study population there was a sentinel lymph node positivity rate (the percentage of lymph nodes testing positive for caner) of 18%. The overall 5-year survival rate was 96%, and the overall 10-year survival rate was 93%. The overall 5-year disease-free survival rate (length of time after primary treatment for a cancer ends that the patient survives without any signs or symptoms of that cancer) was 94% and the overall 10-years disease-free survival rate was 93%.

Patients who did not have lymph node involvement at the time of biopsy had a 98% 5- and 10-year overall survival rate. In comparison, patients with lymph node involvement at the time of biopsy had a 5-year survival rate of 89% and a 10-year survival rate of 81%.

This study concluded that patients with thin melanomas and additional risk factors for recurrence should undergo sentinel lymph node biopsy to assist in determining prognosis.