Advantages of day-before lymphoscintigraphy and undiluted methylene blue dye injections for sentinel lymph node biopsies for melanoma

Timing of sentinel lymph node biopsy and lymphoscintigraphy before surgery for melanoma: A systematic review and meta-analysis

INTRODUCTION

The management of malignant melanomas often involves performing a sentinel lymph node biopsy (SLNB) aided by imaging with lymphoscintigraphy. Whether lymphoscintigraphy should be performed on the same day as the SLNB operation (SD) or the day before (DB) surgery remains debated. This study aims to summarise existing evidence regarding the impact of the relative timings of lymphoscintigraphy and SLNB on clinical outcomes in melanoma.

METHODS

A PRISMA-compliant search was conducted from inception to 28th May 2024. Data were collected on SLNB in melanoma patients who underwent either an SD or DB approach. The following outcomes were extracted from the articles: node identification, recurrence rate and survival outcomes. Pooled effects of outcomes were estimated using the DerSimonian and Laird random-effects model/generalised linear mixed model, where applicable.

RESULTS

A total of 9 studies met the inclusion criteria. Six studies (n = 10, 216) compared SD and DB approach outcomes, while 3 studies (n = 153) compared SD and DB SLNB within the same patient cohort. In the former, no significant difference was found in positivity rates between SD and DB groups (RR 1.03, 95% CI 0.94-1.13, p = 0.475), and recurrence rates were comparable (RR 0.90, 95% CI 0.75-1.07, p = 0.233). SD approach was associated with significantly shorter hospital stays and lower costs, but conflicting results were observed in survival outcomes. In the latter studies, all 3 reported discrepancies between the results of the SD and DB approaches.

CONCLUSION

Current evidence is insufficient to provide a definitive answer. Further research is warranted to conclusively evaluate the impact of SLNB timing on melanoma outcomes and patient care.

Can late lymphoscintigraphy be omitted in the sentinel node procedure in early-stage vulvar cancer?

INTRODUCTION

In the Netherlands, the sentinel lymph node procedure protocol consists of preoperative lymphoscintigraphy combined with intraoperative blue dye for identifying sentinel lymph nodes in early vulvar squamous cell carcinoma. This study aimed at investigating the role of early and late lymphoscintigraphy.

MATERIAL AND METHODS

From January 2015 to January 2019, early and late lymphoscintigraphies of 52 women were retrospectively analyzed. Lymphoscintigraphy was performed 30 minutes (early) and 2.5-4 hours (late) after vulvar injection of ^99m Tc-labeled nanocolloid. We calculated the concordance correlation coefficient (CCC) between number of sentinel lymph nodes detected on both images using the Lins concordance coefficient and correlated with clinicopathological data.

RESULTS

Thirty-four women had a midline tumor and 18 had a lateral tumor. Detection rates with early and late scintigraphy were 88.5% and 98.1%, respectively. Median number of detected nodes was 1.0 (0-7) and 2.0 (0-7). Good statistical correlation between number of sentinel lymph nodes detected on early and late imaging was found (CCC = 0.76) in most patients. In 18 women (35%) a mismatch occurred: a higher number of nodes was detected on late imaging. In 11 of 18 women re-injection was performed because no sentinel lymph nodes were visualized on early images. Late imaging and intraoperative detection showed a good statistical correlation (CCC = 0.61). One woman showed an isolated groin recurrence despite negative sentinel lymph nodes.

CONCLUSIONS

This study showed good statistical correlations between early and late scintigraphy in most patients. However, in 35% of women late scintigraphy detected more nodes. In case of poor visualization after the first scintigraphy, re-injection should be considered. Late scintigraphy is probably helpful in confirming successful re-injection and in showing deviating lymph flow in women with failed mapping after the first injection and successful re-injection. Because missing metastatic sentinel lymph nodes often leads to a poor prognosis, we prefer optimal correlations between imaging and intraoperative identification. Hence, late scintigraphy cannot be safely omitted.