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© 2003 American Society for Clinical Oncology
In Reply:Department of Dermatology, Eberhard Karls University, Tübingen, Germany In our prospective study in a cohort of 2,008 consecutive patients, follow-up examinations with different techniques were evaluated during a period of 25 months.1 P. Saiag suggested we calculate from this database true- and false-positive and true- and false-negative findings for the different examination techniques applied. Following are the results of these additional evaluations.
Examination findings were judged true-positive when metastasis was confirmed by additional examination techniques (eg, histopathology or other imaging techniques) or by the further course of the disease (documented growth of metastasis during the following 6 months). Conversely, if confirmation by these criteria was lacking, findings were judged false-positive. Negative findings for detection of metastasis were judged true-negative when during the following 6 months, no metastasis was observed; conversely, if metastasis occurred during this time period, findings were judged false-negative. Based on these data, the sensitivity of the different examination techniques (ratio, true-positives / true-positives + false negatives), the specificity (ratio, true-negatives / true-negatives + false-positives) the positive predictive value (ratio, true-positives / true-positives + false-positives) and the negative predictive value (true-negatives / true-negatives + false-negatives) were calculated. The respective values are given in Table 1
Lymph node sonography revealed, with 3.9%, the highest rate of true-positive findings of metastasis, followed by physical examination, with 2.0% true-positive findings. Few metastases were found by abdominal sonography (0.6% true-positive findings) and chest x-ray (0.5% true-positive findings). Unexpectedly, the rates of true-positive findings of blood tests were in the same range as those of abdominal sonography and chest x-ray (lactate dehydrogenase [LDH], 0.5% and alkaline phosphatase [AP], 0.4%). However, there is a major difference in the rate of false-positive findings with very low values for abdominal sonography and chest x-ray (<0.2%) and clearly higher values for blood tests (LDH, 2.2%; AP, 2.4%). The highest sensitivity for the detection of the respective metastasis was likewise observed for lymph node sonography, whereas the other imaging techniques showed clearly lower values. The blood tests LDH and AP had the lowest sensitivity of all examination techniques because of their higher rate of false-negative findings. Specificity was approximately 99% for physical examinations, as well as for the imaging techniques, and slightly lower for blood examinations. In the present study, few patients were treated with sentinel lymph node dissection, because this treatment modality was introduced in our department during the study period. Therefore, a specific evaluation of the follow-up examinations in these patients is not yet available. We agree with P. Saiag’s speculation that different results (especially in lymph node sonography) will probably be obtained in future for the collective of patients treated with sentinel lymph node dissection. Further studies are required to outline the impact of sentinel lymph node dissection on follow-up examination of cutaneous melanoma. AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The authors indicated no potential conflicts of interest.
REFERENCE
1. Garbe C, Paul A, Kohler-Späth H, et al: Prospective evaluation of a follow-up schedule in 2,008 patients with cutaneous melanoma: Recommendations for an effective follow-up strategy. J Clin Oncol 21:520–529, 2003
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Copyright © 2003 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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