Dr. Cadili’s Scoring to Predict Non-Sentinel Lymph Node Metastasis in Melanoma
Establishing a Scoring System
Dr. Cadili’s previous work had established a scoring system to predict which melanoma patients with a Positive Sentinel Lymph Node Biopsy (SLNB) were unlikely to have a further disease on other lymph nodes and could be spared surgery. In this study, Dr. Cadili set out to apply this score (developed with University of Alberta patients) to melanoma populations across different centers in Canada for validation.
For this purpose, Dr. Cadili formed a collaborative group of melanoma research with centers across Canada. Data on all melanoma patients over an eight-year period from Toronto SunnyBrook Health Sciences Centre (University of Toronto), the Winnipeg Health Sciences Centre (University of Manitoba), and the Calgary Foothills Medical Centre (University of Calgary) was collected and analyzed. Also, further data from the Misericordia Hospital (University of Alberta) over an additional two year period was collected and analyzed to supplement the cohort.
The result of this more extensive analysis revealed that another factor, thickness of the melanoma, emerged as a critical predictor of further lymph node positivity in melanoma patients with a positive SLNB. In addition, the element that was the most predictive of further lymph node positivity was the size of the melanoma deposit in the sentinel lymph node. Specifically, a newly constructed parameter termed “Total SLN Metastasis” was synthesized by adding up all the reported melanoma deposits in the sentinel lymph nodes. This freshly discovered parameter was the most predictive of further lymph node positivity with cutoff values of 2 mm, and 5 mm is the most prominent.
Determining The Likelihood of Further Lymph Node Disease
This study expands on the previous two studies that refined a score developed to determine which melanoma patients with a Positive Sentinel Lymph Node Biopsy (SLNB) are unlikely to have further lymph node disease and thus can be spared potentially debilitating surgery. For this purpose, Dr. Cadili traveled to the University of Australia, where the Melanoma Institute Australia housed the largest melanoma database in the world.
The goal of the project was to validate the score developed in Canada using the Sydney database. The score Dr. Cadili developed, which was based on patient age and the newly constructed pathological parameter of total SLN size, was applied to melanoma patients in the database treated from 1992 to 2009. The results revealed that this score did not accurately predict further lymph node positivity but did, however, predict patient survival (both overall survival as well as melanoma-specific survival).
Objectives of The Study
Based on our previous results in melanoma patients with a Sentinel Lymph Node Biopsy (SLNB), Total SN (Sentinel Node) tumor size emerged as a uniformly predictive factor of the likelihood of further lymph node disease after SLNB. Total SN size was a construct Dr. Cadili developed that can be easily calculated from the number of melanoma deposits and the size of each deposit in the sentinel lymph node(s). This factor, as mentioned, was validated as predictive of further lymph node disease throughout multiple centers across Canada.
This study aimed to put this through the more definitive validation of applying this parameter to the database of the Melanoma Institute Australia, the largest melanoma database in the world. The other objective of this study was to correlate this parameter as an independent predictor of survival. This was done by collecting data from the database over 17 years from melanoma patients that had a positive SLNB.
Our statistical models revealed that indeed, total SN tumor size was significantly predictive of further lymph node disease. Additionally, it also significantly correlated with patient mortality. Dr. Cadili concludes that this newly developed parameter can be used to guide decisions on whether further lymph node excision surgery is done on melanoma patients with a negative SLNB, especially those at higher risk for developing complications.