The impact of lymphoscintigraphy technique on the outcome of sentinel node biopsy in 1,313 patients with cutaneous melanoma: an Italian Multicentric Study (SOLISM-IMI)

Abstract

An observational multicentric Italian trial on sentinel node biopsy (SNB) in melanoma patients was performed to diffuse a common SNB protocol nationwide (Italy). We report herein the results of this trial. The influence of some technical aspects on the outcome of SNB was also investigated, because a certain degree of variability was accepted in performing lymphoscintigraphy.

Methods: From January 2000 to December 2002, 1,313 consecutive patients with primary cutaneous melanoma (Breslow thickness, >1.0 mm or <1.0 mm but with ulceration, Clark level IV-V, presence of regression) were enrolled by 23 centers. One half to 1 mL of 99mTc-labeled human albumin colloid, at a suggested dosage of 5-15 or 30-70 MBq, was injected intradermally, closely around the scar, the same day or the day before SNB. Intraoperatively, Patent blue was associated when a definitive wide excision of the primary was required. A positive sentinel node (SN) was defined when containing melanoma cells detected by either hematoxylin-eosin or immunohistochemistry (S100 and HMB45 antibodies). All patients underwent regular follow-up. False-negative cases were considered when lymph node metastases occurred in the same lymphatic basin of SN biopsy (SNB) during follow-up. A quality control program has been performed for the surgical procedure and for the histologic diagnosis.

Results: The SN identification rate was 99.3%. The axilla was the site of the SN in 52.5% of the cases. The mean number of SNs was 2.0 (range, 1-17) and only 1 node was removed in 45.4%. The positivity and false-negative rates were 16.9% and 14.7%, respectively (median follow-up, 31 mo). On multivariate analysis (logistic and linear regression) only the number of peritumor injections was inversely associated with the number of excised SNs (P = 0.002), whereas none of the technical variables showed an independent impact on SN status when Breslow thickness was included as a control variable.

Conclusion: The number of peritumor injections seems to influence the outcome of lymphoscintigrapy in melanoma patients undergoing SNB. If these results are confirmed in a controlled trial, 3 injections at least should be recommended.