completion lymph node dissection (CLND), rather than clinical observation and therapeutic lymph node dissection (TLND) when metastases became clinically detectable.124 However, heterogeneity exists amongst SN positive patients, with additional metastases in NSNs found at CLND in 7-33% of cases.123,136–155 In addition, CLND is a major surgical procedure that carries a significant risk of subsequent morbidity when compared with SNB alone.156–158 It is usually assumed, although not proven, that the patients found to have additional nodal metastases at CLND are the only ones who could benefit from the procedure. Following from this assumption, there have been considerable efforts to identify predictors of NSN status with a view to avoiding CLND in those predicted to be NSN negative.123,136–155 The actual significance of NSN status has not been fully determined. The Second Multicenter Selective Lymphadenectomy Trial (MSLT II) is currently under way to determine whether, for SN positive patients, immediate CLND confers any survival advantage over high-resolution ultrasound monitoring and delayed TLND as required.159 However, it is possible that a survival advantage from immediate CLND in a subset of this heterogeneous group may go undetected. For example, at the time of CLND, patients who have metastases confined to nodes that would all be excised at CLND, and have no distant metastases, could be cured by the procedure. Using ultrasound monitoring these nodal metastases would remain within the patient and retain the potential to metastasize to distant sites. Thus, the present study was undertaken to further define and characterize the SN positive population. Specific aims were first to determine the prognostic significance of NSN status. Second, to examine patient and primary tumor characteristics for factors predictive of NSN metastasis. Third, to develop a classification system for SN positive patients that delineates groups with distinctly different survival, and could be useful for selecting patients for clinical trials. METHODS
completion lymph node dissection (CLND), rather than clinical observation and therapeutic lymph node dissection (TLND) when metastases became clinically detectable.124 However, heterogeneity exists amongst SN positive patients, with additional metastases in NSNs found at CLND in 7-33% of cases.123,136–155 In addition, CLND is a major surgical procedure that carries a significant risk of subsequent morbidity when compared with SNB alone.156–158 It is usually assumed, although not proven, that the patients found to have additional nodal metastases at CLND are the only ones who could benefit from the procedure. Following from this assumption, there have been considerable efforts to identify predictors of NSN status with a view to avoiding CLND in those predicted to be NSN negative.123,136–155 The actual significance of NSN status has not been fully determined. The Second Multicenter Selective Lymphadenectomy Trial (MSLT II) is currently under way to determine whether, for SN positive patients, immediate CLND confers any survival advantage over high-resolution ultrasound monitoring and delayed TLND as required.159 However, it is possible that a survival advantage from immediate CLND in a subset of this heterogeneous group may go undetected. For example, at the time of CLND, patients who have metastases confined to nodes that would all be excised at CLND, and have no distant metastases, could be cured by the procedure. Using ultrasound monitoring these nodal metastases would remain within the patient and retain the potential to metastasize to distant sites. Thus, the present study was undertaken to further define and characterize the SN positive population. Specific aims were first to determine the prognostic significance of NSN status. Second, to examine patient and primary tumor characteristics for factors predictive of NSN metastasis. Third, to develop a classification system for SN positive patients that delineates groups with distinctly different survival, and could be useful for selecting patients for clinical trials. METHODS