Dermatology World August 2011 : Page 12
acta eruditorum continued research in practice of patients who have a positive SLNB, the SLNB itself may be curative when there are no other involved nodes. Thus, the vast majority of SLNB patients are being unnecessarily subjected to the additional procedure of TLND without a documented survival benefit. A trial is currently underway investigating this issue because we need to know if a TLND has a survival benefit for patients who have had a positive SLNB. However, it is important to recall that CM patients can have a negative SLNB and still die of metastatic disease. We will need to wait for the results of ongoing studies to determine whether managing SLNB-positive patients without a TLND has a role in melanoma treatment. Dr. vAn voorHees: So, does tumor thickness solely drive the prognosis? Are there other factors that should be considered, such as location of tumor or atypia of the cells? Dr. rHoDes: Breslow tumor thickness is the single best determinant of CM-related survival. Other features that have been significantly associated with disease-specific survival (DSS) based on histopathologic features of the primary tumor include mitotic rate (number of mitotic figures per square millimeter), presence of ulceration, vertical growth phase tumor, microscopic satellitosis, angiotropism, vascular invasion, and fibrotic regression. Other significant prognostic features include tumor volume, quality of tumor-associated lymphohistiocytic infiltrate, anatomic site of the primary tumor, predominant cell type of the primary tumor (spindle cell vs. epithelioid cell), patient sex and age, Clark’s level of invasion, tumor vascularity, and extent of lymphangiogenesis, among others. Prognostic models are available that have incorporated some or many of these features to 12 Dermatology WorlD // August 2011 provide an assessment of DSS. It is anticipated that molecular markers on the primary tumor may eventually be useful in the assessment of DSS. Dr. vAn voorHees: What are the risks of doing SLNB? What are the economic considerations? What is the false negative rate? Dr. rHoDes: The false negative rate can vary from 2.5 percent to 20 percent, dependent on available studies and various definitions. The cost of doing a SLNB ranges from $15,000-19,000, with an average 13 percent risk of surgical complications according to various studies. Moreover, the procedure usually requires a general anesthetic, patient downtime, and significant wound care. SLNB-positive patients will also be offered the additional procedures of TLND and adjuvant interferon therapy, with their associated morbidity and costs but without a clinically significant survival benefit. Dr. vAn voorHees: How does your study fit with current guidelines of care for melanoma and recommended quality measures related to how much interventional care is given for patients who are asymptomatic? Dr. rHoDes: My study deals only with asymptomatic patients. It’s safe to say that for patients with no clinical evidence of disease, doing x-rays, blood tests, or any imaging studies [which Medicare’s quality measures specifically address] is not only useless in terms of enhancing survival, but the false positive rates for these tests will be responsible for additional expense and needless patient worry. Dr. vAn voorHees: A “Practice Gaps” piece accompanied your article; one of the limitations they noted was the small number of studies on which your analysis is based. Dr. rHoDes: I agree with the criticism, which is highlighted in the discussion of my manuscript. Of the large number of SLNB studies I was able to find in the electronic search, there were only 25 informative papers which provided detailed raw numbers required for the Bayesian analysis. Most of the discarded articles provided univariate and/or multivariate analyses. All of the 25 informative published studies had relatively short patient follow-up intervals, and most of the studies included all tumor thicknesses. Relatively few studies I found segregated patients according to tumor thickness, i.e. thin, intermediate, and thick. None of the studies reported the proportion of patients followed for at least five years (or intervening death). Rather than to continue recommending routine SLNB for our patients, I believe that we need a multicenter cooperative study with collation of raw numbers and segregation of data according to tumor thickness, patient age, and the requirement of at least seven-10 years of patient follow-up (or intervening CM-related death). This type of a multicenter study is needed to substantiate or refute the prognostic usefulness of SLNB. For the issue of a minimum required time interval of follow-up in such a study, it is useful to recall the Duke University melanoma follow-up study by Gamel et al ( Cancer 2002;95(6):1286-1293), in which it was shown that for patients who die from metastatic melanoma by 23 years, only 66 percent of these patients died by five years, while 92 percent died by 10 years. I would like to see all future publications about SLNB for CM include raw numbers, including details about follow-up (preferably at least five years or intervening death), that would be amenable to additional studies like the Bayesian analysis provided in my paper. dw Dr. rHoDes is a professor and director of the melanoma intervention clinic in the depart-ment of dermatology at Rush University Medical Center. his article was published in Archives of Dermatology , 147(4), 408–415 (April 2011) after being published online Dec. 20, 2010. doi:10.1001/ archdermatol.2010.371. www.aad.org
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