Impact of clinicopathologic factors on the number of lymph nodes examined in patients with melanoma

Background

Melanoma is amongst the malignancies with the greatest annual increase in incidence. The prognosis for melanoma is partially dependent on lymph node status. Staging of lymph node basins in patients without clinical evidence of lymphadenopathy is typically by sentinel lymph node (SLN) biopsy. In this study, we sought to determine factors associated with the number of sentinel lymph nodes examined.

Methods

The National Cancer Database Participant User File from 2018 to 2020 was queried for clinical node negative patients who underwent sentinel lymph node biopsy. Descriptive statistics were obtained. Stepwise negative binomial regression analysis was performed in addition to ANOVA, chi-squared and Student’s t-tests.

Results

We identified 32,516 clinically node negative patients with melanoma from 2018 to 2020 who had undergone sentinel lymph node biopsy. Using a stepwise negative binomial model, male patients had a 3.8 % increase in the number of SLNs examined compared to females, while each year of age predicted a 0.3 % decrease in the number of SLNs examined. Breslow thickness > 2 mm was associated with a 6.9 % increase in SLN examined. Primary sites with multiple potential lymphatic drainage basins including ear, lip, scalp & neck, and trunk were associated with a 55.2 %, 29.6 %, 46.6 %, 43.4 % increase in SLNs examined, respectively. The study did not identify a difference in overall survival based on the number of lymph nodes examined (p = 0.25).

Conclusion

The number of sentinel lymph nodes examined in melanoma patients is associated positively with younger age, male sex, Breslow thickness, and primary site.

Synopsis

A National Cancer Database study of sentinel lymph node biopsy yield in clinically node-negative melanoma patients showed association with age, sex, Breslow thickness, and primary site. Clinicopathologic factors were predictive of sentinel lymph node yield, indicating other influences rather than objective sentinel lymph node criteria on node biopsy.