The results of a large cohort study suggest that a proportion of patients with cutaneous melanoma could potentially avoid sentinel node biopsy, according to data presented by Moncrieff et al at the Society of Surgical Oncology 2021 International Conference on Surgical Cancer Care (Abstract 59).
Role of Sentinel Node Biopsy
The outcomes of the MSLT-2 and DeCOG studies, in addition to the maturation of data from recent adjuvant systemic therapy trials, have embedded the role of sentinel node biopsy for accurately staging patients with cutaneous melanoma. These findings have simultaneously shifted the treatment paradigm from identifying patients for surgical management of the regional lymph nodes to identifying those eligible for adjuvant systemic therapy.
Adjuvant systemic therapy is usually not routinely recommended for American Joint Committee on Cancer (AJCC) stage IIIA melanoma. Patients with pT1b to pT2a melanoma whose sentinel node biopsies are positive are mostly mapped to AJCC IIIA, which brings into question the role of sentinel node biopsy for these patients.
Methods and Findings
Researchers identified 3,515 patients from nine cancer centers in five countries with AJCC 8th edition stage IB primary cutaneous melanoma. The investigators analyzed patient demographics, primary tumor characteristics, sentinel node biopsy status/details, and their association with survival outcomes.
The overall sentinel node biopsy positivity rate was 11.5% (403 of 3,515). Virtually all sentinel node biopsy–positive patients (401 of 403; 99.5%) were AJCC stage IIIA. The 0.1-mm difference in mean Breslow thickness between sentinel node biopsy–positive and –negative patients was significant, but not clinically relevant (P < .001).
A mitotic rate of ≥ 2/mm² identified 67.5% of all sentinel node biopsy–positive patients and 74.0% of all stage N2 to N3 and/or extracapsular spread. The incidence of mitotic rate ≥ 2/mm2 was 55.8%. Mitotic rate ≥ 2/mm² was the only significant, independent predictor of relapse-free, distant disease–free, nodal relapse–free, and disease-specific survival on multivariate analysis (hazard ratios = 3.78, 3.35, 4.11, and 2.98, respectively; all P < .0001).
“The results of this large cohort study would suggest that, with the new modern treatment paradigm, a proportion of pT1b to pT2a patients could potentially avoid sentinel node biopsy, since the management of these patients may remain unchanged, regardless of sentinel node status,” said the study authors. “The role of sentinel node biopsy for mitotic rate ≤ 1/mm² tumors may merit further clarification.”
