Predicting the spread of melanoma

This study examined the frequency of deep lymph node metastasis in melanoma, the consequences of this metastasis on disease progression and survival, as well as ways to predict which patients may experience deep lymph node metastasis.

Lymph node metastases are common in melanoma (when the cancer cells spread from the tumor site to the lymph nodes) and are detected either by feeling an enlarged node or by sentinel node biopsy. Sentinel node biopsy is a test to determine whether cancer cells are present in the lymph node  nearest to the tumor. This test is generally recommended for patients with melanomas larger than 1 millimeter.

Melanoma that has spread to a lymph node could then spread throughout the body, so removing the affected nodes should stop the spread of the disease. In both complete lymph node dissections (removal of affected lymph nodes detected by biopsy) and therapeutic lymph node dissections (removal of affected lymph nodes detected by touch), superficial (close to the surface) and deep lymph nodes can be removed. However, deep lymph node dissection can lead to more surgical complications, and there has been some debate as to whether it is necessary for all patients. #

There is currently no way to predict which patients could also have deep lymph node metastases if they have affected superficial nodes.

The current study examined how often deep lymph node metastasis was found in patients who underwent either complete or therapeutic lymph node dissections and whether it was possible to predict who those patients would be.

The records of 129 patients who underwent either therapeutic (67) or complete (62) lymph node dissection were examined in this study. Patients were followed for an average of 23 months following the procedure. Each patient had an average of 10.4 superficial and 5.3 deep lymph nodes removed. Further affected superficial lymph nodes were found in 47% of complete lymph node dissection patients and 100% of therapeutic lymph node dissection patients. Affected deep lymph nodes were found in 13% of complete lymph node dissection and 31% of therapeutic lymph node dissection patients.

Patients with three or more affected superficial lymph nodes following a complete lymph node dissection were 20 times more likely to have affected deep lymph nodes. Patients with 3 or more affected superficial lymph nodes following a therapeutic dissection were 3.79 times more likely to have affected deep nodes.

The percentage of patients who did not die from the cancer was 74% at 2 years and 54.1% at 5 years for those who underwent complete lymph node dissection and had only superficial lymph node metastasis, compared to 28.6% (2 years) and 14.3% (5 years) for those who had both superficial and deep metastases. After therapeutic lymph node dissection, the percentage of patients who did not die from the cancer was 65.2% at 2 years and 37.2% at five years for those who had only superficial metastasis, and 41.4% (2 years) and 16.6% (5 years) for those who had both superficial and deep metastases.

For patients with deep lymph node metastases, 75% who underwent a complete dissection experienced a distant recurrence of the disease, compared to 13% with only superficial nodes affected. 59% with deep node involvement who underwent a therapeutic dissection experienced a distant recurrence, compared to 46% with only superficial affected nodes.

This study concluded that deep lymph node metastases can significantly affect survival and recurrence rates in melanoma. One possible predictor of deep lymph node metastasis is the number of affected superficial lymph nodes.