Older age is associated with a lower rate of lymph node metastasis

The authors evaluated the association between age and sentinel lymph node metastasis in melanoma.

It has previously been reported that patient age is a highly significant and independent predictor of survival outcome in melanoma. For patients with localized melanoma (stage I and II melanoma; the tumor has not spread), the average tumor thickness at presentation for patients over 70 years of age was almost twice that of patients who were 40-60 years of age.

This study hypothesized that older patients with localized melanoma might have a higher incidence of nodal metastases (spread of the cancer to the lymph nodes), which may offer an explanation as to why they exhibit a lower survival rate.

This study followed 7,756 patients who underwent sentinel node biopsy (surgery that takes out lymph tissue from the first lymph node to which cancer is likely to spread to look for cancer). 19.4% of patients (1,507 patients) had at least one sentinel lymph node metastasis.

There was a significant decrease in the incidence of sentinel node metastasis as patient age increased. 25.8% of patients under 20 years of age had sentinel lymph node metastasis. Only 15.5% of those over 80 years of age had sentinel lymph node metastasis despite the observation that these older patients had primary tumor features associated with more aggressive biology.

Among patients with stage I melanoma who underwent a sentinel lymph node biopsy, the incidence of sentinel node metastases decreased from 14.8% for patients aged 20-30 years to 3.6% for those 80 years of age or older. Among patients with stage II melanoma, the incidence of sentinel node metastases decreased from 35.6% for those 20 years and under to 20.2% for those 80 years or older.

Compared to those above 60 years of age, those aged below 40 years of age had an 80% increased risk of having sentinel lymph node metastasis while those aged from 40-59 years of age had a 40% increased risk. Compared to those without lymphovascular invasion (spread of cancer to blood and lymph vessels), those with lymphovascular invasion had 3 times the risk of having metastasis to the sentinel lymph node. Increasing thickness and primary tumor ulceration were also associated with increased risk of sentinel lymph node metastasis.

The authors stated that the study results emphasize the importance of patient age as a component of melanoma staging.