Is There an Indication for Sentinel Lymphadenectomy

For more than a century, the value of elective lymph node dissection in patients with melanoma has been debated [3-6]. Now that the method of lymphatic mapping and sentinel lymphadenectomy offers the opportunity to reliably identify regional nodes with microscopic involvement [1], this debate has shifted to the issue of ''selective'' lymph node dissection (i.e., completion removal of regional lymph node basin only if there is microscopic involvement of the sentinel node). Several retrospective studies have provided evidence suggesting that this ap proach has a beneficial effect. Patients who underwent node dissection at the stage of microscopic involvement had a survival advantage of approximately 20%, compared to patients who underwent dissection of clinically detected involved nodes [7]. In addition, a prospective randomized trial of the WHO Melanoma Program showed that patients with truncal melanoma, whose microscopically involved nodes were removed electively, fared significantly better than those who underwent delayed dissection for palpable nodes [8].

A definite answer with respect to the value of the procedure can only be expected to come from a randomized prospective study. Fortunately, such a study is ongoing in the form of the Multicenter Selective Lymphadenectomy Trial that was initiated by the person who first described the method, D. L. Morton [9]. In this trial, patients with a melanoma 1 mm or greater in thickness according to Breslow or level IV or greater according to Clark are randomized between wide excision of the primary lesion only, versus wide excision plus sentinel node biopsy followed by a completing regional node dissection in case of microscopic involvement of this node. As endpoints, the possible survival benefit of the latter approach will be balanced against acute and possible long-term side effects of the diagnostic procedure. Long-term side effects may consist of the trapping of tumor cells that are ''in-transit'' between the primary tumor and the regional lymph node basin. Also, unpredictable lymphatic spread due to alterations in lymph flow patterns, and hematogenous spread may occur as well as an increase in the rate of regional recurrence [10].

The identification of a subgroup of patients (definable by Breslow thickness or by other prognostic variables) for which sentinel lymphadenectomy possibly will lead to benefit may be another outcome of the above-mentioned trial. At present, the lower limit of thickness to perform a sentinel lymphadenectomy varies between 0.75 mm and 1.5 mm, whereas most investigators do not set an upper limit. Interesting conclusions in this regard were drawn in a report on a mathematical model that was generated to predict sentinel node involvement [11]. This model was based on two significant predictors for positive sentinel nodes: Breslow thickness and age. These two factors emerged after a multivariate analysis using stepwise logistic regression of age, gender, Clark level, Breslow thickness, presence of ulceration, location, and number of nodal basins. In individual patients, this model can be used for counseling purposes regarding the likelihood of metastatic disease in the sentinel nodes. It can also be used routinely to identify subgroups of patients who will have the most to gain from the procedure. Better noninvasive staging procedures, both for regional and systemic disease, may also further refine the selection of patients for sentinel node biopsy. Currently available noninvasive regional staging procedures are ultrasound, combined with aspiration cytology [12,13], computed tomography (CT) scanning [14], magnetic resonance imaging (MRI), and positron emission tomography (PET). Promising results on the use of sonography have been published. Until now, the use of monoclonal antibodies for the detection of regional metastases has lacked sensitivity [15]. Results regarding the prediction of the occurrence of hematogenous metastasis, however, are encouraging. Multimarker reverse transcriptase-polymerase chain reaction (RT-PCR) techniques have been developed to detect malignant melanoma cells in the blood and lymph nodes [16-18]. The presence of specific tumor markers for melanoma, such as the new sensitive immunolumino-metric assay, LIA-matĀ®SangtecĀ® 100 (S-100), seems to be a useful prognostic parameter for hematogenous spread [19].

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How To Prevent Skin Cancer

How To Prevent Skin Cancer

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