Title: The Role of Sentinel Lymph Node Biopsy for Melanoma: Evidence Assessment
Authors: Johnson TM, MD, Sondak VK, MD, Bichakjian CK, MD, Sabel MS, MD
Source: Journal of American Academy of Dermatology ; 54(1): 19-27.
PODIATRIC RELEVANCE:
Melanoma, although a rare occurrence, does present in the feet. Podiatrists are paramount in the surgical treatment of this condition when that happens. Unfortunately, there are situations where metastases to the lymphatic system may have occurred. Sentinel lymph node biopsy (SNLB) is a diagnostic tool used to identify those individuals who need complete lymph node dissection as a result of lymph node involvement. Better understanding of this allows for a more complete awareness of our patients’ condition and allows for better patient care. This article aims to evaluate the role of SNLB through the review of current literature.
METHODS:
The data reviewed included interim results of a prospective randomized Multicenter Sentinel Lymphadenectomy Trial (MSLT)-I, 1198 articles from the National Institutes of Health National Library of Medicine, and 300 articles from PUBMED. The articles were then stratified based on the strength of the study from best to worst as follows: (1) randomized clinical trials (double-blind or nonblinded); (2) observational studies and published reports (longitudinal cohort studies, case control studies/cross-sectional studies, case series or case reports); and (3) prevailing expert opinion and clinical experience (review articles/book chapters, or the authors’ expertise). The articles and data were used to answer a series of five questions posed by the authors.
RESULTS:
Does the available evidence support the sentinel node hypothesis? The sentinel node hypothesis is the belief that an orderly progression of cancer cells occurs in the initial stage of metastasis within the lymphatic system. Strong evidence supports the hypothesis that the SLN is the first draining node and that there is evidence to support the use of SLNB to accurately identify the SLN in primary melanoma. The highest success rate in accurately identifying the SLN is through a combination of preoperative lymphoscintigraphy, intraoperative gamma probe interrogation, and intraoperative injection of vital blue dye. False negatives are attributed to three main causes: technical failure (inexperience, after extensive excision or flap reconstruction), pathologic failure (due to sensitivity of histopathology methods such as staining and sectioning), and biologic failure (when lymphatics are obstructed by melanoma cells). Does SNLB accurately predict outcome? Strong evidence is available to support SNL status as the most powerful independent predicting factor of survival with the highest sensitivity and specificity compared to any other nodal staging test. Does SLNB result in improved regional disease control? This question has not been addressed by previous studies. The MSLT-I will attempt to answer this question. Currently the failure rate of SLNB is 0-10% for complete lymph node dissection (CLND) after a positive SLNB or ELND and 9-36% after CLND for grass disease. Does SNLB improve survival? There is no high-level evidence that exists to support this however lower-level evidence does suggest the benefit. MSLT-I interim results after 5 years and 7 years provide strong high-level support for the prognostic benefit of SLNB. It was also shown that immediate CLND after a positive SLNB prolongs survival compared to delayed CLND when SLN metastasis became clinically evident. Is the morbidity of SLNB justified in the absence of a proven survival benefit? Review shows that SNLB carries an overall 4.6% complication rate compared to 23.2% complication rate of CLND after a positive SLNB.
COMMENTS:
The article is thorough in its attempt to review current data to address the controversies associated with SLNB. In doing so, a better understanding SNLB’s role in the management of melanoma is achieved. There seems to be promising support for the use of SLNB in not only the prediction of survival but also improving survival in light of new research in this area. Gaining a better understanding of this topic and its associated concerns is invaluable in the discussion of prognosis with our patients.
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Disclaimer:
Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.