Hot dots - which nodes should be removed in sentinel lymph node biopsy for melanoma?

BACKGROUND: Sentinel lymph node biopsy (SLNB) is a critical staging tool for melanoma patients. The optimal number of lymph nodes removed in SLNB remains unclear. In this study, we retrospectively analysed and tested different criteria for selecting sentinel lymph nodes (SLNs) by radiotracer uptake and blue dye, and their impact on nodal staging. We also evaluated the association between SLN tumour burden and radiotracer uptake. METHODS: The study population consisted of melanoma patients undergoing SLNB. During the operation all radioactive and blue nodes were removed and sent for histopathological analysis. The ex vivo radioactive count and presence of blue dye of each node were recorded, and these were correlated with presence and size of metastasis in each SLN. RESULTS: Altogether 175 patients with clinically occult metastasis presented with one or more positive, i.e. metastatic, SLNs. The mean number of lymph nodes removed was 4.5, and the mean number of positive lymph nodes was 1.5 per patient. The most radioactive or hottest node was negative in 38 patients (22%). By removing the hottest node and all nodes with radioactivity >10% of the hottest node, 97% of patients would have been staged correctly. In five patients, metastasis was found solely in a SLN with radioactivity <10% of the hottest node. Of all 267 positive nodes removed, 125 (47%) contained blue dye. Patients with a negative hottest node were associated with lower SLN tumour burden. CONCLUSIONS: By removing the hottest node and all nodes with radioactivity >10% of the hottest node, 97% of patients with SLN metastases are correctly staged with or without using blue dye.

Pelvic sentinel lymph nodes have minimal impact on survival in melanoma patients.

BACKGROUND: Lower limb or trunk melanoma often presents with femoral and pelvic sentinel lymph nodes (SLNs). The benefits of harvesting pelvic lymph nodes remain controversial. In this retrospective study, the frequency and predictors of pelvic SLNs (PSLNs), and the impact of PSLNs on survival and staging was investigated. METHODS: Altogether 285 patients with cutaneous melanoma located in the lower limb or trunk underwent sentinel lymph node biopsy of the inguinal/iliac lymph node basin at Helsinki University Hospital from 2009-2013. Patient characteristics, detailed pathology reports and follow-up data were retrieved from hospital files. Subgroups of patients categorized by presence of PSLNs were compared for outcome parameters including progression-free survival, melanoma-specific survival and groin recurrence. RESULTS: Superficial femoral/inguinal SLNs were present in all patients and 199 (69.8 per cent) also had PSLNs removed. Median number of SLNs per patient was five and median number of PSLNs was two. Sixty-three patients (22.1 per cent) had metastases in their SLNs and seven (2.5 per cent) had metastases in PSLNs. A single patient had metastases solely in PSLNs, while superficial SLNs remained negative. Harvesting PSLNs or the number of PSLNs retrieved had no impact on progression-free survival or overall survival. The removal of PSLNs did not affect the risk of postoperative seroma or lymphoedema. The only predictor of positive PSLNs was radioactivity count equal to or more than that of the hottest superficial SLNs. CONCLUSION: Pelvic SLNs have minimal clinical impact on the outcome of melanoma patients especially in cases with negative superficial femoral/inguinal SLNs. Removal of PSLNs should be considered when they are the most radioactive nodes or equal to the hottest superficial femoral/inguinal SLNs in lymphoscintigraphy or during surgery.Preliminary results were presented in part at the International Sentinel Node Society Biennial Meeting, Tokyo, Japan, 11-13 October 2018.

Increased gene expression levels of collagen receptor integrins are associated with decreased survival parameters in patients with advanced melanoma.

Expression of collagen receptor integrins alpha1beta1 and alpha2beta1 has been associated with progression and metastatic potential of malignant melanoma. Integrin alpha2beta1 was originally characterized as a melanoma progression antigen. We have used real-time quantitative PCR to study the mRNA expression levels of three collagen receptor integrin chains, that is alpha1, alpha2 and alpha11 in metastases from 26 patients with melanoma. Interestingly, we find that survival after initiation of chemoimmunotherapy was significantly decreased in all patients whose tumours expressed high mRNA levels of alpha1 integrin, alpha2 integrin or alpha11 integrin when compared with lower tumour expression levels (P<0.05, log rank test). Moreover, those patients with high mRNA levels of all studied integrins had a significantly shorter survival from the appearance of the first metastasis than the patients with low levels of integrins (P<0.05). Furthermore, a high mRNA expression level of integrin alpha2 was found to be associated with poorer overall survival. High alpha2 mRNA levels (n=6) were associated with median survival of 35 months and low alpha2 mRNA levels (n=20), with median survival of 53 months (P=0.033). We conclude that collagen receptor integrins are important in the progression and prognosis of metastatic melanoma, and their measurements might be used as predictive markers when assessing disease progression.