The management of regional lymph nodes in cancer

Metastases of malignant neoplasms: Historical, biological, & clinical considerations

The metastasis of neoplastic cells from their site of origin to distant anatomic locations continues to be the principal cause of death from malignant tumors, and that fact has been recognized by physicians for over a century. After the work done by Halsted in the treatment of breast cancer in the 1880s, accepted surgical canon held that metastasis occurred in a linear fashion, with centrifugal "growth in continuity" from the primary neoplasm that first involved regional lymph nodes. Those structures were considered to then be the sources of more distant, visceral metastases. With that premise in mind, radical and "ultra-radical" surgical procedures were devised to remove as many lymph nodes as possible in the treatment of carcinomas and melanomas. However, such interventions were ineffective in altering tumor-related mortality. This review considers the details of the historical material just mentioned. It also reviews currently-held concepts on biological mechanisms of metastasis, the "sentinel" lymph node biopsy technique, and the important topic of metastatic tumor "dormancy" as the cause of surgical treatment failure. Finally, predictive models of tumor behavior are discussed, which are based on gene signatures. These will likely be the key to identifying malignant lesions of low surgical stage that ultimately prove fatal through later manifestation of metastasis.

Evidence-Based Principles in Pathology: Existing Problem Areas and the Development of “Quality” Practice Patterns

Context.—Contrary to the intuitive impressions of many pathologists, several areas exist in laboratory medicine where evidence-based medicine (EBM) principles are not applied. These include aspects of both anatomic and clinical pathology. Some non-EBM practices are perpetuated by clinical “consumers” of laboratory services because of inadequate education, habit, or overreliance on empirical factors. Other faulty procedures are driven by pathologists themselves.

Objectives.—To consider (1) several selected problem areas representing non-EBM practices in laboratory medicine; such examples include ideas and techniques that concern metastatic malignancies, “targeted” oncologic therapy, general laboratory testing and data utilization, evaluation of selected coagulation defects, administration of blood products, and analysis of hepatic iron-overload syndromes; and (2) EBM principles as methods for remediation of deficiencies in hospital pathology, and implements for the construction of “quality” practices in our specialty.

Data Sources.—Current English literature relating to evidence-based principles in pathology and laboratory medicine, as well as the authors' experience.

Conclusions.—Evidence-based medicine holds the promise of optimizing laboratory services to produce “quality” practices in pathology. It will also be a key to restraining the overall cost of health care.

Tumor lymphatics

In this article we survey more than three centuries of observation and research into tumor-associated lymphatic vessels, and their role in the metastatic spread of cancer. This historical overview documents how questions regarding tumor lymphatics have been central to concepts about the process of metastasis, and how this has subsequently influenced the clinical treatment of cancer. In turn, we show how analysis of the efficacy of these treatments has challenged long-standing notions regarding the tumor lymphatics. Starting with the discovery of VEGFR-3 and its ligands VEGF-C and VEGF-D, we also review how the rapid developments over the last 15 years in the molecular analysis of the lymphatic system and in particular lymphangiogenesis have contributed to this debate. Finally we speculate on how apparently paradoxical bodies of evidence regarding the role of tumor lymphatics in determining patterns of metastatic spread might be reconciled.

Medicolegal liability in surgical pathology: a consideration of underlying causes and selected pertinent concepts

Malpractice actions against surgical pathologists are still relatively uncommon, but they have increased in frequency over time and are associated with sizable indemnity figures. This discussion categorizes areas of liability in surgical pathology into three groups: those that represent health system flaws (problems with specimen identification, or transportation, or both; lack of clinical information or erroneous information; sampling effects and defects; and poorly reproducible or poorly defined diagnostic or prognostic criteria), others that exist at the interface between the system and individuals (allowing clinicians to bypass pathologic review of referred specimens; acceding to clinical demands for inadvisable procedures; and working in a disruptive environment), and truly individual errors by pathologists (lapses in reasoning; deficiencies concerning continuity in the laboratory; invalid assumptions regarding recipients of surgical pathology reports; over-reliance on the results of "special" tests; and problems with peer consultation). Finally, two important topic areas are discussed that commonly enter into lawsuits filed against surgical pathologists; namely, "delay in diagnosis" of malignant neoplasms and "failure to provide adequate prognostic information." Based on a review of the pertinent literature, we conclude that the clinical courses of most common malignancies are not affected in a significant manner by delays in diagnosis. Moreover, the practice of using "personalized external validity" for supposedly prognostic tests is examined, with the resulting opinion that prognostication of tumor behavior in individual patients is not reliable using anything but anatomic staging systems.

Evidence-based principles and practices in pathology: selected problem areas

Contrary to the intuitive impression of most pathologists, there are still many areas in laboratory medicine where evidence-based medicine (EBM) principles are not applied. These include aspects of both anatomic and clinical pathology. Some non-EBM practices are perpetuated by clinical "consumers" of laboratory services, because of inadequate education, habit, or over-reliance on empirical factors. Other faulty procedures are pathologist-driven, with similar underpinnings. This overview considers several exemplary problem areas representing non-EBM practices in the hospital laboratory. Such examples include ideas and techniques centering on metastatic malignancies, "targeted" oncological therapy, analysis of surgical margins in the excision of neoplasms, general laboratory testing and data utilization, evaluation of selected coagulation defects, administration of blood products, and analysis of hepatic iron-overload syndromes. The concepts illustrating departures from EBM are discussed for each of those topics.

Selective sentinel lymphadenectomy: progress to date and prospects for the future

The sentinel node (SN) concept was clearly outlined by Virchow in the mid-nineteenth century, and Braithwaite used the term "glands sentinel" in 1923. However, it was not until Morton, Cochran et al. published their landmark report in 1992 that the clinical relevance of the SN was fully appreciated. Since then, the validity of the concept has been confirmed in studies undertaken at a number of centers worldwide. It has become clear that SN status accurately reflects the status of the entire regional node field, not only in patients with melanoma but also in those with breast cancer and a wide range of other primary malignancies. New insights into lymphatic anatomy have been gained by preoperative lymphoscintigraphy, and the original blue dye mapping technique for SN identification has been supplemented by intraoperative use of a hand-held gamma probe to identify radioactivity in colloid particles injected at the primary tumor site. It has become clear that all three methods are required to achieve optimal accuracy of SN identification. Although SN assessment provides very important prognostic information, the results of randomized trials must be awaited to determine whether selective sentinel lymphadenectomy, with full regional node dissection if a positive SN is found, is of any therapeutic value. It is possible that SN positivity is merely a marker of disease that has the potential for hematogenous dissemination and systemic metastasis. As follow-up times extend, reported false-negative SN rates are increasing, and ways to reduce these false-negative rates are therefore being actively sought. Attempts are being made to increase the accuracy of SN identification, and to confirm true SN identity both at the time of surgery and retrospectively. The ultimate objective is to develop minimally invasive and even non-invasive methods of SN assessment, Proton magnetic resonance spectroscopy is one technique that might make it possible to achieve this goal, and avoid the present morbidity and cost of operative SN removal.