Survival outcomes and interval between lymphoscintigraphy and SLNB in cutaneous melanoma- findings of a large prospective cohort study

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.

Next day sentinel node biopsy for melanoma after lymphoscintigraphy using 99mTc-labelled nanocolloid does not adversely affect long-term outcomes

OBJECTIVE

Sentinel Lymph Node Biopsy (SLNB) is an important management tool for early-stage melanoma. Different radiopharmaceuticals are used internationally to localise the sentinel node using lymphoscintigraphy (LSG) before surgery. Recent reports have suggested that a delayed interval between LSG and SLNB using 99mTc-labelled nanocolloid tracer has an adverse survival impact, but not with 99mTc-labelled antimony sulphide colloid. This study aims to analyse survival outcome in a prospective cohort of melanoma patients undergoing same day or next day SLNB after LSG using 99mTc-labelled nanocolloid.

METHODS

Outcome data were reviewed for patients undergoing SLNB, stratified by time interval between LSG and SLNB at a single UK academic centre. Kaplan-Meier survival analysis was used to assess overall survival (OS), melanoma-specific survival (MSS) and progression-free survival (PFS). Cox multivariable regression analysis identified independent risk factors.

RESULTS

925 patients had LSG using the 99mTc-nanocolloid tracer between 2009 and 2019, with a median follow-up of 6.36 years. No difference was seen on univariate analysis in OS, MSS, PFS, or nodal recurrence between patients undergoing same day or next day SLNB (Log-rank P = 0.437, 0.293, 0.587, 0.342 respectively). In addition, nodal recurrence as first site or anytime site of recurrence in SLNB negative patients was similar between the groups (Log-rank P = 0.093 and 0.457 respectively). Stratified analysis of time did not demonstrate an outcome difference (MSS Log-rank P = 0.938). Cox multivariable regression did not show time interval to independently influence OS, MSS or PFS.

CONCLUSIONS

We do not find a significant effect on long-term outcomes when SLNB is performed the day after LSG with 99mTc-labelled nanocolloid tracer. We infer that tracer migration is not clinically significant within 24 h of injection based on long term clinical outcome data.

The worse survival outcomes reported for melanoma patients having sentinel node biopsy after lymphoscintigraphy the previous day do not appear to be due to overnight migration of Tc99m-nanocolloid tracer

INTRODUCTION

It has been reported that the survival of patients having sentinel node (SN) biopsy for melanoma the day after lymphoscintigraphy using Tc99m-nanocolloid is worse than that of patients having lymphoscintigraphy and SN biopsy on the same day [1,2]. A possible explanation suggested is that overnight migration of the tracer from SNs to 2nd-tier nodes occurs, causing failure to remove true SNs.

MATERIALS AND METHODS

The possibility of overnight tracer migration leading to errors in SN-identification was investigated in 12 patients scheduled for lymphoscintigraphy the day before surgery by repeating SPECT-CT imaging the next morning, before their SN biopsy. The aim was to check whether onward migration of colloid from previously-identified SNs had occurred.

RESULTS

No significant migration of Tc99m-nanocolloid occurred overnight in any patient. All nodes reported to be SNs on day 1 imaging were also present and regarded as SNs on day 2 images. No new foci were visualised on day 2, but some that had been identified on day 1 were not seen on day 2.

CONCLUSIONS

Since migration of nanocolloid overnight did not occur, this cannot explain the reported survival disadvantage for patients undergoing SN biopsy the day after lymphoscintigraphy. A likely alternative possibility is that inadequate doses of radioisotope were used for next-day procedures, causing the mistaken removal of 2nd-tier nodes instead of true SNs more frequently. Further research is required to explain the reported reduction in survival of patients having next-day SN biopsy procedures, since the possibility has important clinical implications.

Effect of delay between nuclear medicine scanning and sentinel node biopsy on outcome in patients with cutaneous melanoma

BACKGROUND

Sentinel lymph node biopsy (SLNB) is an important staging tool for the management of melanoma. A multicentre study was done to validate previous findings that the timing of lymphoscintigraphy influences the accuracy of SLNB and patient outcomes, particularly survival.

METHODS

Data were reviewed on patients undergoing SLNB for melanoma at three centres in the UK and Sweden, examining the effect of timing of SLNB after nuclear medicine scanning. Kaplan-Meier survival analysis was used to assess overall (OS), disease-specific (DSS) and progression-free (PFS) survival, stratified by timing of lymphoscintigraphy. Independent risk factors for survival were identified by Cox multivariable regression analysis.

RESULTS

A total of 2270 patients were identified. Median follow-up was 56 months. Univariable analysis showed a 4·2 per cent absolute and 35·5 per cent relative benefit in DSS (hazard ratio 1·36, 95 per cent c.i. 1·05 to 1·74; P = 0·018) for 863 patients whose SLNB was performed up to 12 h after lymphoscintigraphy compared with 1407 patients who had surgery after more than 12 h. There were similar OS and PFS benefits (P = 0·036 and P = 0·022 respectively). Multivariable analysis identified timing of lymphoscintigraphy as an independent predictor of OS (P = 0·017) and DSS (P = 0·030). There was an excess of nodal recurrences as first site of recurrence in the group with delayed surgery (4·5 versus 2·5 per cent; P = 0·008).

CONCLUSION

Delaying SLNB beyond 12 h after lymphoscintigraphy with ⁹⁹ Tc-labelled nanocolloid has a significant negative survival impact in patients with melanoma.