The incidence of low volume metastases according to Silva pattern in cervical adenocarcinoma undergoing sentinel lymph node biopsy

Objective: Silva pattern is associated with higher risk of lymph node metastasis in cervical adenocarcinoma. However, no study specifically assessed the correlation between Silva pattern and sentinel lymph node (SLN) metastasis after ultrastaging. The primary aim of this study was to assess the incidence of low volume metastases in SLN of patients undergoing primary surgery with SLN biopsy for cervical adenocarcinoma, according to Silva pattern. Secondary aims were to assess risk factors for lymph node metastasis and prognosis. Methods: Retrospective, multi-center study. Patients with cervical adenocarcinoma clinical FIGO stage IA1 to IIA2, treated with primary surgery between 04/2015 and 12/2023 and undergoing SLN mapping attempt, were included. Low volume metastases were defined as any tumor deposit ≤2 mm (ITC as <0.2 mm, micro-metastasis as 0.2-2 mm). Appropriate statistical analysis was performed to assess study endpoints. Results: 153 patients were included. Bilateral SLN mapping was achieved in 133 (86.9%) women. Silva pattern A was present in 47 (30.7%), B in 51 (33.3%) and C in 55 (35.9%) patients. 14 (9.1%) patients had metastatic SLN and 2 (1.4%) had metastatic non-SLN. The incidence of low-volume metastasis was 10/133 (7.5%) in patients with bilateral SLN mapping: 7 (5.3%) in Silva C, 1 (0.7%) in Silva B, and 2 (1.5%) in Silva A, while macro-metastases occurred in 4/133 (3.0%): 3 (2.2%), 0 and 1 (0.7%) cases, respectively (p = 0.027). Silva pattern C was the only factor independently associated to lymph node metastasis at multivariable analysis (OR: 9.724; 95%CI: 1.468-64.402; p = 0.018). No difference in disease-free survival and overall survival was evident when comparing Silva patterns (p = 0.210 versus p = 0.305, respectively). Conclusion: Low-volume metastases are more frequent than macro-metastases in patients with cervical adenocarcinoma undergoing SLN biopsy. Silva pattern C was associated with higher incidence of low volume lymph node metastasis, and it was the only factor independently associated with lymph node metastasis. Lymph node macro- and low-volume metastases were found also in Silva pattern A and B, highlighting the potential need for nodal assessment by SLN biopsy also in these sub-groups of patients.