For patients newly diagnosed with thin melanoma, age is an important factor in assessing whether they have positive lymph nodes, according to recent research published in JAMA Dermatology.

National guidelines for when to perform sentinel lymph node biopsy in patients newly diagnosed with melanoma focus on pathology and not patient factors such as age. The authors concluded that age should be taken into consideration when choosing which patients undergo nodal biopsy. “Current guidelines for sentinel lymph node biopsy may be overly restrictive in younger patients and overly permissive in older patients,” the researchers stated.

In a retrospective cohort study using data from the National Cancer Database, researchers conducted data analysis on 8772 patients with clinical stage 1 thin melanoma (0.50-1.0 mm). All patients had wide excision and surgical evaluation of regional lymph nodes (LNs). The primary outcome was presence of melanoma in a biopsied regional LN, and classification tree analysis was performed to find high-risk groups for LN positivity. The median age was 56 years, with 1379 (15.7%) and 2655 (30.3%) patients being younger than 40 years and 65 years or older, respectively.


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Results showed that 333 patients were found to have regional nodal metastases on surgical lymph node evaluation (rate, 3.8%; 95% CI, 3.4%-4.2%) Further findings revealed that patient age was an important risk stratifier for LN metastases after mitosis and thickness. Multivariable analysis showed that younger age, female sex, Breslow thickness of 0.76 mm or more, increasing CLARK level, mitoses, ulceration, and lymphvascular invasion were independently related to LN positivity.

Using decision tree analysis, patients younger than 40 years with category T1b tumors (0.50-0.75 mm), who would typically not be recommended for sentinel lymph node biopsy, had a LN positivity rate of 5.6% (95% CI, 3.3%-8.6%), whereas patients aged 65 years or older with T1b tumors 0.76 mm or larger, who would usually be referred for sentinel lymph node biopsy, had a LN positivity rate of only 3.9% (95% CI, 2.7%-5.3%).

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“Since more than half of new invasive melanoma diagnoses present as clinically localized thin melanoma, identification of subgroups in whom [sentinel lymph node biopsy] has a higher yield has important implications for proper use of health care resources,” the researchers wrote. “Conversely, recognition of patients in whom the procedure has a low yield may help to reduce morbidity.”

The researchers note that the chance of misclassification and selection bias suggest the need for further studies to validate these findings.

Reference

Sinnamon AJ, Neuwirth MG, Yalamanchi P, et al. Association between patient age and lymph node positivity in thin melanoma [published online July 19, 2017]. JAMA Dermatol. doi: 10.1001/jamadermatol.2017.2497.