β3 integrin immunohistochemistry as a method to predict sentinel lymph node status in patients with primary cutaneous melanoma

Sentinel lymph node assessment in melanoma: current state and future directions

Assessment of sentinel lymph node status is an important step in the evaluation of patients with melanoma for both prognosis and therapeutic management. Pathologists have an important role in this evaluation. The methodologies have varied over time, from the evaluation of dimensions of metastatic burden to determination of the location of the tumour deposits within the lymph node to precise cell counting. However, no single method of sentinel lymph node tumour burden measurement can currently be used as a sole independent predictor of prognosis. The management approach to sentinel lymph node-positive patients has also evolved over time, with a more conservative approach recently recognised for selected cases. This review gives an overview of past and current status in the field with a glimpse into future directions based on prior experiences and clinical trials.

Association of tumor molecular factors with in-transit metastasis in primary cutaneous melanoma

BACKGROUND

In-transit metastases (ITM) are a form of locoregional relapse representing intralymphatic metastatic spread and occur in approximately 4-9% of patients with melanoma >1 mm Breslow thickness. Our objective was to evaluate a combination of clinicopathologic risk factors and gene expression biomarkers predictive of ITM risk.

METHODS

We used PCR to quantify gene expression in diagnostic biopsy tissue across a prospectively designed archival cohort of 854 consecutive thin and intermediate thickness primary cutaneous melanomas. The outcome of interest was ITM >90 days after a melanoma diagnosis. Cox proportional hazard models were fit to estimate each clinicopathologic and molecular characteristic's association with the risk of ITM.

RESULTS

The 5-year cumulative incidence of ITM was 3.2%. Clinical factors univariately associated with an increased risk of ITM were older age, greater Breslow thickness, greater mitotic rate, lower extremity location, ulceration, and a positive SLN biopsy. Of 108 genes tested, five were significantly upregulated and five significantly downregulated when evaluated in Cox models adjusted for age, Breslow thickness, mitotic rate, and lower extremity location. Among the upregulated genes, the strongest association was observed for interleukin-8 (IL8).

CONCLUSION

A subset of gene expression biomarkers was identified as independently associated with the risk of ITM after adjusting for key covariates. Once sufficiently validated, our results may lead the way to regional therapy trials for a small, selected group of high-risk patients.

Using the Merlin assay for reducing sentinel lymph node biopsy complications in melanoma: a retrospective cohort study

BACKGROUND

The assessment of the sentinel lymph node is a cornerstone of melanoma staging. However, ~80% of sentinel lymph node biopsies (SLNB) are negative and nontherapeutic, and patients are unnecessarily exposed to surgery-related complications. Here, we gauged the potential of the Merlin assay to reduce SLNB-associated complications. The Merlin assay uses clinicopathologic variables and tumor gene expression profiling to identify low-risk patients who may forgo SLNB.

METHODS

We utilized the Merlin test development cohort to determine SLNB complication rates for procedures performed between 2004 and 2018 at Mayo Clinic. Complications evaluated were lymphedema, seroma, infection/cellulitis, hematoma, and wound dehiscence. Patients who underwent a completion lymph node dissection were excluded.

RESULTS

A total of 558 patients were included. The overall 90-day complication rate specific to SLNB (1 year for lymphedema) was 17.4%. The most common complications were seroma (9.3%), infection/cellulitis (4.8%), and lymphedema (4.3%). All three were more common in patients with a lower extremity primary tumor location versus other locations. With Merlin test results applied, SLNB-related complications would have decreased by 59%.

CONCLUSION

SLNB is a safe procedure but carries a significant complication rate. Merlin testing might reduce the need for SLNB and its associated complications.