Predictive Factors for Metastasis of Skin Melanoma of Varying Thickness According to Breslow to Sentinel Lymph Nodes
Authors: Nikolaeva E. A. , Krylov A. S. , Ryzhkov A. D. , Abdulova L. Y. , Bilik M. E. , Zakharova T. V. , Baryshnikov K. A. 
Published: October 2021

Purpose: To evaluate the prognostic factors in patients with Breslow skin melanoma of various thicknesses that affect the incidence of metastases in the signal lymph nodes (SLN).

Material and methods: From November 2018 to November 2020, 324 patients with diagnosed melanoma of the skin of various localization and stages were examined and operated on. We used lymphotropic colloidal radiopharmaceutical (RPh) labeled with 99mTc. RPh with an activity of 150 MBq was administered one day before the operation intradermally around the scar of resected melanoma or peritumorally at 4 points in the case of a primary tumor. Lymphoscintigraphy was performed 1–3 hours after the RP injection on a Symbia E or Symbia E gamma camera (Siemens, Germany). Anteroposterior and lateral static polypositional scintigraphy was performed to determine the topography and mark the SLN. 324 planar studies were performed. In 259 cases, an additional study was performed SPECT (including SPECT / CT) on a Symbia T2 device (Siemens, Germany). Surgical intervention was performed the next day, taking into account the data of intraoperative radiometry using a domestic specialized hand-held gamma detector Radical (Amplituda, Russia).

Results: The mean primary melanoma Breslow thickness was 2.77 ± 2.2 mm (range 0.2–13.0 mm). Localization of SLN: axillary (n = 161. 51 %), inguinal (n = 100. 31 %), cervical (n = 16. 5 %), submandibular (n = 9. 3 %), supraclavicular (n = 4. 1 %), more than one basin (n = 34. 9 %). In the group of melanomas <0.75 mm thick, no SLN metastases were found, among 0.75–1 mm melanomas, one positive lymph node with metastasis (SLN+) was found, in the largest group of melanomas of medium thickness (1–3.5 mm) — 25 (17 %). The largest percentage of metastases in SLN is determined in thick melanomas (>3.5 mm) — 17 (28 %), which is consistent with the data of foreign literature, while SLN is most often affected with a Breslow tumor thickness of more than 7 mm.

In the group with negative sentinel lymph nodes (SLN–), the average tumor thickness according to Breslow was 2.6 ± 2.0 mm, in the SLN+ group — 4.0 ± 2.9 mm, the differences between the groups are statistically significant, which is confirmed by the result of one-way analysis of variance.

The optimal threshold value of tumor thickness according to Breslow for the isolation of patients with a positive prognosis of metastasis in the SLN is 2.0 mm. It is characterized by the maximum levels of sensitivity (79 %) and specificity (59.1 %). An older age of patients (over 35 years old) is also associated with an increased incidence of metastases in the SLN, but this indicator is not statistically significant. Most often, SLN metastases were detected when the primary tumor was localized in the back (more often in men) and lower extremities (more often in women), while they are thicker (> 3.5 mm).

Conclusion: 1. According to the ROC-analysis, the optimal threshold value of the tumor thickness according to Breslow for the isolation of patients with a positive prognosis of metastasis in the SLN is 2.0 mm. It is characterized by the maximum levels of sensitivity (79 %) and specificity (59.1 %). 2. Statistically significant prognostic factors of metastasis in SLN: localization of the primary tumor in the back (more often in men) and lower extremities (more often in women); Breslow thickness over 3.5 mm. 3. The absence of the influence of gender and age was noted, with a slight predominance of women in both groups.