E321: An evaluation of sentinel lymph node biopsy guideline adherence in melanoma patients

Introduction: Regional lymph nodes are the most common first site of melanoma metastasis. Identification of nodal metastases, assessed using sentinel lymph node biopsy (SLNB), is critical for staging and selecting treatment. The National Comprehensive Cancer Network (NCCN) recommends considering SLNB for melanomas with T-stage T1b or greater. We aimed to assess NCCN guideline adherence at our institution.

Methods: Retrospective review from 9/2017-2/2023 identified 396 patients referred to our academic center with melanoma. Data regarding demographics, melanoma characteristics, and treatment were collected from the medical record. Statistical analyses included t-tests and Chi-square analyses.
 

Results: Median age was 67 years, and 55% were male. Mean Breslow thickness was 1.9 mm. Of 396 patients, 217 underwent SLNB (54.8%). Of T1a patients, 12/156 (7.7%) received SLNB compared to 205/239 (85.8%) with T1b or greater. Positive SLNs were found in 39/217 cases (T1a = 0%; T1b = 2%; T2a = 16%; T2b = 17%; T3a = 33%; T3b = 30%; T4a = 38%; T4b = 36%). In total, 11.7% of cases did not adhere to NCCN guidelines; however, 82.6% of these provided clinically reasonable justifications (Table 1). Head and neck melanomas (n = 58) were more likely to not receive SLNB contrary to guidelines compared to other locations (22.7% vs. 9.0%, p = 0.001). Age > 65 and medical comorbidities did not affect guideline adherence (p = 0.46 and p = 0.37). Patients with SLNB care plans contrary to guidelines were more likely to have melanoma recurrence (p = 0.019). Of the 17 recurrences, 11 underwent SLNB per guidelines, and 5/6 patients not receiving SLNB were nonadherent to guidelines. Of the 5 nonadherent patients, recurrences occurred at the primary site (n = 2), lymph nodes (n = 3), and distant (n = 3), with 2/5 patients recurring in multiple areas. In patients who received a SLNB per guidelines, recurrences occurred at the primary site (n = 4), lymph nodes (n = 8), distant (n = 6), and multiple areas (n = 6).

Conclusions: Most melanoma cases aligned with NCCN guidelines for SLNB with only an 11.7% rate of discordance. Cases proceeding contrary to guidelines without justification elicit the need for adequate documentation. Patients who did not receive the recommended SLNB had a higher likelihood of recurrence; however, these recurrences were not isolated to the nodal basin. Compared to patients adherent to guidelines, both groups had similar recurrence patterns. Therefore, in well-selected patients, it may be reasonable to not offer SLNB without affecting clinical outcomes. Lastly, this analysis provides a blueprint for quality improvement studies at other centers.