Barrier function of lymph node to tumor cells and erythrocytes. I. Normal nodes

The Evolution of the Sentinel Node Biopsy in Melanoma

The growing repertoire of approved immune-checkpoint inhibitors and targeted therapy has revolutionized the adjuvant treatment of melanoma. While the treatment of primary cutaneous melanoma remains wide local excision (WLE), the management of regional lymph nodes continues to evolve in light of practice-changing clinical trials and dramatically improved adjuvant therapy. With large multicenter studies reporting no benefit in overall survival for completion lymph node dissection (CLND) after a positive sentinel node biopsy (SLNB), controversy remains regarding patient selection and clinical decision-making. This review explores the evolution of the SLNB in cutaneous melanoma in the context of a rapidly changing adjuvant treatment landscape, summarizing the key clinical trials which shaped current practice guidelines.

A Short History of Bernard Fisher's Contributions to Randomized Clinical Trials

Dr. Bernard Fisher (1918-2019) was an early proponent of evidence-based medicine using the mechanism of prospective, multicenter, randomized clinical trials to test biological and clinical hypotheses. In this article, I trace how his early scientific work in striving to understand the nature of cancer metastasis through animal experiments led to a new, testable, clinical hypothesis: that surgery to remove only the tumor and a small amount of tissue around it was as effective as the more disfiguring operations that were then the standard treatment. Fisher's work with the National Surgical Adjuvant Breast and Bowel Project (NSABP) using large, randomized clinical trials to demonstrate the veracity of this hypothesis led to a new paradigm in which the emphasis was placed on how systemic therapies used at an early stage of disease could effectively eradicate breast cancer for many patients. This new therapeutic approach led to the successful development of new treatments, many of which are widely used today. Ultimately, the new paradigm led to successfully preventing breast cancer in women who were at high risk for the disease but who had not yet been diagnosed with the disease. Throughout his entire career, Fisher championed the use of large prospective, randomized clinical trials despite criticism from many in the medical community who strongly criticized his use of randomization as a mechanism for testing clinical hypotheses. The approach he and the NSABP employed is still considered to be the highest standard of evidence in conducting clinical studies.

Sentinel Node Methods in Penile Cancer - a Historical Perspective on Development of Modern Concepts

Malignant penile tumors are of squamous cell origin in more than 95% of cases and the occurrence of a distant metastasis without prior inguinal lymph node metastatic deposits is very rare. This makes inguinal lymph node staging very reliable and of great prognostic significance since undiscovered and untreated inguinal metastases may lead to a fatal clinical course. In lack of a sufficiently accurate noninvasive lymph node staging modality, penile cancer relies on surgical lymph node removal for regional staging. In this respect sentinel node biopsy offers a favourable minimally invasive alternative to prophylactic inguinal lymph node dissection which is associated with significant surgery-related morbidity. Today sentinel node biopsy is widely used in surgical oncology within high volume cancers such as breast cancer and melanoma. In rare cancers sentinel node biopsy is also emerging as a minimal invasive staging tool in patients with no obvious lymph node involvement. At several specialized units across Europe sentinel node biopsy has been practiced by dedicated specialist within vulva and penile cancer for more than two decades. In fact, the rare disease penile cancer was a model entity for development of the original sentinel node concept as early as the 1970'es due to work by the Paraguayan penile cancer pioneer, Cabañas, the sentinel node concept was subsequently successfully adapted in breast cancer and melanoma. This turned out mutually beneficial since the sequential development of sentinel node biopsy in penile cancer in the 1990s eventually adopted new insights and added conceptual details from the experiences harvested in the broader clinical application possible in these high-volume diseases. The prerequisite to conceptualising the sentinel node approach was the gradual anatomical and functional understanding of the lymphatic system which in western medicine rooted in ancient Greece and gradually increased in details and comprehension with significant contributions from many great notabilities during the last centuries including Hippocrates, Galen, Fallopio, Malpighi, Virchow, Starling, Cabañas, Hodgkin and Horenblas. Sentinel node biopsy in penile cancer is a complex multimodality procedure involving inguinal ultrasonography by radiologists, precise tracer-injection and interpretation of nuclear images by nuclear medicine physicians, radio-tracer- and dye guided open surgical biopsies by urologists and thorough step-sectioning, immunostaining and accurate lymph node specimen analysis by pathologists. This team effort requires well-tested protocols, experience and good collaboration and in rare diseases this calls for centralization of service.

Practice patterns about the role of palliation in veterinary surgical oncology

Whether surgical palliative therapy is appropriate for oncologic veterinary patients is an increasing concern as pet age increases because of improved care. In this study, an online survey (available for 30 days), comprising 100 questions with structured response options, was administered to 492 diplomates of the European College of Veterinary Surgeons (ECVS). The survey queried the technical, ethical, social, medical, and financial aspects of surgical palliative therapy for oncologic veterinary patients. Responses were received from 155 ECVS diplomates (31.5%, n = 155/492). Palliative surgery was a relatively common intervention in veterinary oncology, with 50% of respondents (n = 77.5/155) indicating that 75%-100% of oncological surgeries performed were palliative. The presence of metastasis was judged as a key determinant when deciding to perform palliative oncological surgery by 41% of the respondents (n = 63.5/155). The survey revealed that the most commonly performed procedures in palliative oncological surgery were marginal resection, debulking, and amputation. In contrast to human medicine, palliative limb-sparing surgery, stent placement, and embolization were rarely used in veterinary settings, mainly because of a general lack of expertise among veterinarians, elevated costs, and recourse to euthanasia. Taken together, the survey results highlight the need for appropriate guidelines in the field of oncological surgery. To establish general guidelines and direct veterinarians towards the most appropriate judgement, understanding how and what veterinary surgeons manage palliative oncological surgery and how they perceive the main ethical, social, medical, and financial concerns are essential. Such guidelines will lead to better care for ailing animals and will facilitate the path to healing for owners.

Paradigm shift in the local treatment of breast cancer: mastectomy to breast conservation surgery

There have been fundamental changes in the approach to breast cancer management over the last century but the primary objective of achieving oncological safety remains unchanged. This evolution is highlighted with a summary of the key evidences in support of the oncological safety of breast conserving surgery (BCS) in early breast cancer (EBC) management. We will also discuss the increasingly pivotal role that neoadjuvant chemotherapy (NACT) may play, in the local treatment of EBC and locally advanced breast cancer (LABC) and the long-term surgical and oncological outcomes.

A longitudinal MRI study on lymph nodes histiocytosis of a xenograft cancer model

BACKGROUND

Efforts are continuously made to detect and investigate the pivotal processes and interplay between the response of sentinel lymph node and malignant cells from a primary tumor. Conversely, some frequently used tumor animal models, such as human cancer xenografts, rarely feature metastasis. Therefore, lymph node alterations are seldom assessed. We consider that studying lymph node response could contribute to the understanding of host reaction to cancer. In the present study, we explored the presence of regional lymph node alterations in parallel with tumor growth using a pancreatic tumor xenograft model which does not develop metastasis.

METHODS AND FINDINGS

We established an animal cancer model by the subcutaneous inoculation of PANC-1 (a metastatic human pancreatic cancer cell line) in the left upper flank of athymic nude mice. Tumor animals, along with controls (n = 7 / group) were subjected to Magnetic Resonance Imaging (MRI) in order to follow tumor growth and brachial and axillary lymph nodes alterations over several weeks. Further histological analyses were performed at the end of the study. The individual average of the different lymph nodes sizes was 15-40% larger in the tumor animals compared to control animals at week 8 to week 20. The tumor size and lymph node size were not correlated. Histological analysis of the lymph nodes showed paracortical histiocytosis. No metastasis to lymph nodes could be detected by histology. In tumor bearing animals, histiocytosis was associated with isolated apoptotic bodies and migration of human tumoral cells was confirmed by specific immunostaining of human origin markers.

CONCLUSIONS

The lack of metastasis as well as the pathological manifestation of the lymph node alteration in this pre-clinical model established here parallels findings in patients with sinus histiocytosis that is correlated with improved survival.

A historical account of breast cancer surgery: beware of local recurrence but be not radical

In the late 19th century, William Halsted proposed the radical mastectomy, which became the standard surgical treatment of breast cancer for nearly 100 years. Later in this period, theories suggesting that breast cancer was a systemic disease at inception were championed by Bernard Fisher. This alternative hypothesis of biological predeterminism was based upon results of randomized clinical trials comparing breast conserving therapy with mastectomy, which showed similar overall survival outcomes. Nonetheless, data from meta-analyses suggest that inadequate local therapy can increase risk of local recurrence, which can subsequently increase mortality. In this review, the authors provide an historical account of how local therapy of breast cancer has evolved in the face of improved adjuvant therapies and better understanding of disease biology.

Molecular mechanisms and imaging of lymphatic metastasis

In many types of cancer, tumors metastasize through the lymphatic system to draining lymph nodes. These sentinel lymph nodes have gained increased attention as a prognostic indicator for the severity of the disease, leading to the sentinel lymph node mapping and biopsy procedure to be accepted as standard-of-care for breast cancer and melanoma. However, many limitations exist with this procedure resulting in high false negative rates. In this review we highlight the new advances in the understanding of the molecular mechanisms of lymphangiogenesis and tumor metastasis that may lead to improved strategies in the detection of the sentinel lymph nodes and therapeutic interventions to prevent further tumor spread. In addition, advances in imaging technology are allowing new approaches for anatomical mapping of lymphatic drainage patterns and molecular imaging strategies that may improve detection of metastatic tumor cells within sentinel lymph nodes.

Real-time imaging of the lymphatic channels and sentinel lymph nodes of the stomach using contrast-enhanced ultrasonography with Sonazoid in a porcine model

The contrast-enhanced ultrasound (CEUS)-guided method in combination with Sonazoid has not been clinically or experimentally evaluated with regard to its use for identifying sentinel lymph node (SLN) in the stomach. Therefore, we attempted to evaluate the usefulness of the CEUS-guided method with Sonazoid for imaging of the lymphatic channels and SLN of the stomach in a porcine model by comparing it with the conventional Evans blue dye-guided method. Twenty-eight 2 to 3-month-old swine weighing 17-30 kg were used in this experiment. Anesthesia was maintained with 2.0-3.0% isoflurane/O(2) inhalation. Sonazoid was injected into the intra- and sub-mucosal layers of the stomach. The intragastric or transcutaneous CEUS-guided method was used to identify the lymphatic channels and SLN of the stomach. Contrast imaging using the CEUS-guided method with Sonazoid enabled us to produce clear images of the afferent lymph vessel and SLN of the stomach until 2 h after the injection of Sonazoid. In addition, intranodal flow of the microbubble agent could be clearly identified using tissue linear harmonic images of the SLN. The SLN detection rate was not significantly different between the CEUS- and dye-guided methods. However, the Evans blue dye flowed out quickly (≈ 15 min after the injection) through the true SLN into the next LN of stomach. In conclusion, the use of the CEUS-guided method with Sonazoid might be the most useful clinical procedure for producing real-time images of the SLN of the stomach, and the linear harmonic images are also useful for evaluating intranodal structure within the SLN.

The role of lymph node metastasis in the systemic dissemination of breast cancer

BACKGROUND.: Lymphatic invasion is necessary for regional lymph node (RLN) metastasis in breast cancer (BC), while systemic metastasis requires blood vessel (BV) invasion. The site of BV invasion could be at the primary BC site or through lymphovascular anastomoses. The vague pathologic term "lymphovascular invasion" (LVI) encourages the belief that peri/intratumoral BV invasion may be common. We investigated the relative contribution of RLN metastasis to systemic metastasis by studying the relationship among LVI and RLN and/or systemic metastasis in a population-based cohort of breast cancer patients. METHODS.: Fisher's exact test was done to assess global associations among LVI and RLN and/or systemic metastasis in a prospective database of breast cancer patients undergoing RLN biopsy. Logistic regression was used to determine multivariable contributions of LVI to metastasis when controlling for available demographic, radiologic, and pathologic variables. RESULTS.: Of 1668 patients evaluated 25.4% were RLN positive and 10.4% had LVI. RLN metastasis was predicted by tumor size (P < .0001), HER-2/neu overexpression (P = .0022) and the interaction between LVI positive and HER-2/neu positive tumors (< .0001). Patients with LVI/HER-2-neu positive were 3 times as likely to have positive RLNs compared with patients LVI/HER-2-neu negative. Systemic metastasis was significantly (P = .0013) associated with LVI/ RLN positive, but not with LVI positive/RLN negative patients (P = .137). CONCLUSIONS.: LVI predicted RLN metastasis. LVI also significantly predicted systemic metastasis, but only when the RLN was also positive. Since RLN requires lymphatic invasion, these data support the hypothesis that primary breast cancers often invade lymphatics to gain access to the systemic circulation.

The role of lymph node metastasis in the systemic dissemination of breast cancer

BACKGROUND

Lymphatic invasion is necessary for regional lymph node (RLN) metastasis in breast cancer (BC), while systemic metastasis requires blood vessel (BV) invasion. The site of BV invasion could be at the primary BC site or through lymphovascular anastomoses. The vague pathologic term "lymphovascular invasion" (LVI) encourages the belief that peri/intratumoral BV invasion may be common. We investigated the relative contribution of RLN metastasis to systemic metastasis by studying the relationship among LVI and RLN and/or systemic metastasis in a population-based cohort of breast cancer patients.

METHODS

Fisher's exact test was done to assess global associations among LVI and RLN and/or systemic metastasis in a prospective database of breast cancer patients undergoing RLN biopsy. Logistic regression was used to determine multivariable contributions of LVI to metastasis when controlling for available demographic, radiologic, and pathologic variables.

RESULTS

Of 1668 patients evaluated 25.4% were RLN positive and 10.4% had LVI. RLN metastasis was predicted by tumor size (P < .0001), HER-2/neu overexpression (P = .0022) and the interaction between LVI positive and HER-2/neu positive tumors (< .0001). Patients with LVI/HER-2-neu positive were 3 times as likely to have positive RLNs compared with patients LVI/HER-2-neu negative. Systemic metastasis was significantly (P = .0013) associated with LVI/RLN positive, but not with LVI positive/RLN negative patients (P = .137).

CONCLUSIONS

LVI predicted RLN metastasis. LVI also significantly predicted systemic metastasis, but only when the RLN was also positive. Since RLN requires lymphatic invasion, these data support the hypothesis that primary breast cancers often invade lymphatics to gain access to the systemic circulation.

MDA-MB-231 produces ATP-mediated ICAM-1-dependent facilitation of the attachment of carcinoma cells to human lymphatic endothelial cells

We examined the effects of supernatants of culture media of MDA-MB-231 and MCF-7 cells on the expression of adhesion molecules on human lymphatic endothelial cells (LECs) and evaluated whether the overexpression of adhesion molecules facilitated the attachment of carcinoma cells to LECs. The 48-h stimulation of MDA-MB-231, but not MCF-7, supernatant produced a significant expression of ICAM-1 on human LECs but little or no expression of E-selectin. Chemical treatment with dialyzed substances of <1,000 molecular weight (MW) caused a complete reduction of the supernatant-mediated response. In contrast, pretreatment with heating, digestion with protease, or chemical treatment with dialyzed substances of <500 MW produced no significant effect on the supernatant-mediated response. ATP (10(-7) M) caused overexpression of ICAM-1 on human LECs similar to that produced by the supernatant of MDA-MB-231. The ATP- and MDA-MB-231 supernatant-mediated responses were significantly reduced by treatment with 10(-6) M suramin (a purinergic P2X and P2Y receptor antagonist). In attachment assays, 10(-7) M ATP or MDA-MB-231 supernatant produced a significant increase in the attachment of carcinoma cells to human LECs. The treatment with 10(-6) M suramin caused a significant reduction of ATP- and supernatant-mediated facilitation of the attachment responses. Additional treatment with anti-ICAM-1 antibody also caused a significant reduction of ATP- and supernatant-mediated facilitation of the attachment responses. The experimental findings suggest that MDA-MB-231 may release or leak ATP, which produces the overexpression of ICAM-1 on human LECs through activation of purinergic P2X and/or P2Y receptors and then facilitates ICAM-1-mediated attachment of carcinoma cells to LECs.

Tumor cell-organ microenvironment interactions in the pathogenesis of cancer metastasis

The process of cancer metastasis is sequential and selective and contains stochastic elements. The growth of metastases represents the endpoint of many lethal events that few tumor cells can survive. Primary tumors consist of multiple subpopulations of cells with heterogeneous metastatic properties, and the outcome of metastasis depends on the interplay of tumor cells with various host factors. The findings that different metastases can originate from different progenitor cells account for the biological diversity that exists among various metastases. Even within a solitary metastasis of proven clonal origin, however, heterogeneity of biological characteristics can develop rapidly. The pathogenesis of metastasis depends on multiple interactions of metastatic cells with favorable host homeostatic mechanisms. Interruption of one or more of these interactions can lead to the inhibition or eradication of cancer metastasis. For many years, all of our efforts to treat cancer have concentrated on the inhibition or destruction of tumor cells. Strategies both to treat tumor cells (such as chemotherapy and immunotherapy) and to modulate the host microenvironment (including the tumor vasculature) should offer additional approaches for cancer treatment. The recent advances in our understanding of the biological basis of cancer metastasis present unprecedented possibilities for translating basic research to the clinical reality of cancer treatment.

Cutaneous melanoma: therapeutic lymph node and elective lymph node dissections, lymphatic mapping, and sentinel lymph node biopsy

Early clinical observation in cancer patients suggested that tumors spread in a methodical, stepwise fashion from the primary site, to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers, at least temporarily preventing the widespread dissemination of tumor. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics in cancer patients for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection, and most recently lymphatic mapping and sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall patient survival for cancer of any type, including melanoma, after surgical excision of regional lymphatics. This article will review the biology of lymphatics as it relates to regional tumor metastasis, and based on available information, offer practical recommendations for the clinical dermatologist and their patients who have cutaneous melanoma.

The Effect of Radiation Therapy on Normal Tissue Function

As more patients are treated for their primary malignancy with cure or increased disease-free intervals, injury to normal tissues will become more detectable and an important endpoint for study. Future protocols will probably be modified based on toxicity endpoints. In Hodgkin's disease, current protocols use response-based treatment strategies to limit therapy. The objective is to provide the same level of tumor control and follow normal tissue endpoints for outcome analysis. DVH analysis has improved the ability to analyze endpoint data for normal tissues. These image-guided platforms will provide the infrastructure needed to continue efforts in improving the delivery of radiation therapy.

Rationnels de la chirurgie oncologique au sein d’un traitement multimodal des cancers

The permanent dissemination of circulating cancer cells from infiltrative cancers renders the notion of localized cancer obsolete. This raises the question of the role of treatments such as surgery which are localized in time and space. Moreover, it is now proven that surgery increases the number of circulating cancers cells and produces transient immunodepression which promotes cancer cell implantation. In addition, the healing process stimulates growth factors, which also act on tumor growth. In spite of these deleterious effects, oncological surgery remains an important tool in the anti-cancer armamentarium. Optimal cytoreductive surgery facilitates the effect of adjuvant treatments by eliminating the vascular sanctuaries present in the center of any large tumor and by its effect as a striking-force very localized in time and space. Oncological surgery must evolve as an integrative part of our improving understanding of tumor biology, taking into account recent developments in functional imaging, genomics and proteomics. Modalities and timing must be reconsidered for oncological surgery to play its proper role as one of the many components contributing to multimodal cancer treatments. New modalities will undoubtedly be necessary with the development of future technologies.

Limited Capability of Regional Lymph Nodes to Eradicate Metastatic Cancer Cells

The capacity of lymph nodes to eradicate cancer is a controversial issue. The purpose of this study was to determine the interplay between tumor growth and host resistance at early stages of lymph node metastasis. A metastasis model was made in the rat mesenteric lymph node, and migration of cancer cells was visualized in vivo. The lymph node was removed for histologic analysis and cytokine measurement. Migrant cancer cells were initially arrested in the marginal sinus. After an initial increase, the number of cancer cells in the marginal sinus declined until 48 hours after inoculation. Germinal centers and lymphoid cells in the medulla proliferated before 48 hours. ED3(+) macrophages incorporated apoptotic cancer cells, but significant cancer proliferation occurred after 4 days. Lymph nodes depleted of macrophages were massively invaded by cancer cells. Tumor necrosis factor alpha and interleukin (IL)-1beta in the nodes transiently increased after 1 hour and 3 hours, respectively, and were expressed in ED3(+) and ED2(+) macrophages, respectively. These changes were followed by a transient increase in IL-2. Interferon-gamma and IL-12 did not increase during the early stages of metastasis, but they decreased after 48 hours. In conclusion, the marginal sinus constitutes a mechanical barrier against cancer cell passage. Early pathological manifestations in the regional lymph node are consistent with those in cancer patients with improved survival. Parasinus macrophages play a role in the transient antimetastatic capability of the node, and cytokines secreted by these cells increased at the early stages of metastasis. Deterioration of cytokine induction may be responsible for subsequent cancer proliferation.

Histologic heterogeneity and intranodal shunt flow in lymph nodes from elderly subjects: a cadaveric study

Gaps of the superficial cortex of the lymph node provide intranodal shunts that are more often the cause of skip metastasis than are collateral vessels. Examination of lymph nodes from cadavers of elderly subjects often revealed cortical gaps, especially in specific three-dimensional assembled cords; these cortical gaps were readily seen in para-aortic and pelvic nodes. This architecture seemed to be more appropriate for a systemic immune response than a local defense. Evidence of poorly developed cortices, anthracosis, and hyalinization also suggested impaired nodal function. We suspect that this histologic heterogeneity, perhaps a result of aging, affects the nodal trapping of colorimetric/isotopic tracers and metastatic cancer cells. This may have implications for lymphatic mapping of the sentinel lymph node in elderly patients with early-stage cancer.

Gaps and fragmentation of the superficial cortex in the abdominal and pelvic lymph nodes of elderly Japanese

Gaps and fragmentation of the superficial lymph node cortex are considered to provide intranodal shunt flow between the afferent and efferent vessels. Using serial sections of 205 nodes obtained from 27 donated cadavers more than 70 years of age, we examined the histological architecture of the abdominal and pelvic nodes in elderly Japanese. Secondary follicles were rare in the specimens. Cortex gaps were, to a greater or lesser degree, found in all nodes. We classified these nodes into three types according to how often the gap occurred. Type 1 nodes, with a relatively complete shield for the afferent lymph, were most frequently found in gastric nodes, whereas type 3 nodes, with numerous gaps, were often observed in the colic, para-aortic and pelvic nodes. The type 3 nodes showed a specific architecture characterized by a fragmented superficial cortex, three-dimensionally assembled cords and a common sinus between them. Primary follicles were located in the assembled cord structures as well as at the superficial cortex. Irrespective of the type, B and T lymphocyte areas were intermingled in the cortex-like areas. The present results reveal region-specific histological heterogeneity in aged human visceral nodes. Due to increased surface areas, the type 3 architecture seemed to accelerate systemic immunity rather than act as a local barrier in the para-aortic and pelvic nodes, which are located centrally along the lymphatic drainage routes. However, thick trabeculae often seemed to develop in the type 3 sinus to decrease nodal function with aging.

The management of regional lymph nodes in cancer

Early clinical observation in cancer patients suggested that tumours spread in a methodical, stepwise fashion from the primary site to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers preventing the widespread dissemination of tumour. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection and most recently sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall survival for patients with cancer of any type undergoing surgery of the regional lymphatics. We believe the presence of tumour in the regional lymphatics indicates the presence of systemic disease, and therapeutic interventions should be directed accordingly.

Afferent and efferent lymph-collecting vessels of the submandibular nodes with special reference to the lymphatic route passing through the mylohyoid muscle

BACKGROUND

Although metastasis of cancer in the oral region to the submandibular node is well described, there has been no anatomic representation of lymph vessels penetrating the oral floor and draining into the node.

MATERIALS AND METHODS

Ninety specimens were obtained from formalin-fixed, donated cadavers. Histologic observations using serial sections followed the macroscopic observations.

RESULTS

In 19 of 90 specimens, we found afferent collecting lymph vessels exiting from the mylohyoid surface and draining into the preglandular submandibular node. In 3 of the 19 specimens, collecting vessels passing through the narrow muscle gap with or without arteries, veins, and nerves were identified histologically. The postglandular submandibular node was not evident in the drainage route.

CONCLUSIONS

Although it carries a low incidence, because of the direct lymphatic route or pathway between the oral region and preglandular submandibular node, the pathologically positive supraomohyoid node sometimes seems to be found even in elective neck dissection. However, we speculate that sentinel node investigation would reveal the much more critical role of the jugulodigastric node not only as the actual sentinel node but also as the common terminal node along the various drainage routes from the oral region.

Significado prognóstico das micrometástases nos linfonodos do carcinoma colorretal: detecção imunoistoquímica com anticorpos anticitoqueratina AE1/AE3

OBJETIVOS: Identificar por imunoistoquímica eventuais micrometástases nos linfonodos regionais previamente considerados livres pelo exame histopatológico convencional e avaliar a influência do comprometimento destes linfonodos na sobrevivência dos doentes com carcinoma colorretal extirpado com intenção curativa. MÉTODO: Foram estudados 51 doentes portadores de carcinoma colorretal nos estádios A (13 casos) e B (38 casos), segundo a classificação de Dukes. Um total de 501 linfonodos previamente considerados livres pelo exame histopatológico convencional foi investigado por meio de técnica imunoistoquímica com anticorpos monoclonais anticitoqueratina AE1/AE3 para identificar células epiteliais. Cada bloco previamente fixado em formalina e embebido em parafina foi seccionado em três partes, obtendo-se de cada uma delas três cortes com espessura de 4 milimícron cada. RESULTADOS: Em seis doentes (11,7%) no estádio B de Dukes, células neoplásicas foram identificadas em sete linfonodos do mesocolo (1,4%) previamente considerados livres de neoplasia pelo exame histopatológico convencional. Em um enfermo, a micrometástase era representada por aglomerado celular, enquanto que nos outros cinco doentes as micrometástases eram constituídas por células isoladas. A sobrevivência dos enfermos com micrometástases linfonodais foi menor do que a dos doentes com linfonodos não comprometidos, porém sem atingir diferença significativa. CONCLUSÕES: O método imunoistoquímico pode ser empregado com sucesso na detecção de células neoplásicas em linfonodos previamente considerados livres pelo exame histopatológico convencional. O acometimento dos linfonodos regionais por micrometástases não influenciou a sobrevivência dos doentes com carcinoma colorretal extirpado.

Last-intercalated node and direct lymphatic drainage into the thoracic duct from the thoracoabdominal viscera

OBJECTIVE

We clarified the configuration of the mediastinal lymphatics, focusing on the last intercalated lymph node and the direct drainage vessel to the thoracic duct, based on recent anatomical findings.

METHODS

We macroscopically observed the lymphatics during dissections of 205 cadavers in combination with routine histology. We also review the results of injection by other researchers.

RESULTS

Efferent vessels draining directly into the thoracic duct or venous angle were frequently found in the following node groups: the right paratracheal node group corresponding to the last intercalated node in 98% of cadavers (201); the brachiocephalic angle node group in 85% of cadavers (174); the right recurrent nerve group in 46% (94); the left superior phrenic node group in 73% (150); the node group at the origin of the left common carotid artery (the preaortico-carotid node) in 37% (76); the pretracheal node group in 25% (51) and the left tracheobronchial node group in 36% (74). Last intercalated nodes appeared common for multiple drainage routes or regional lymphatics. These results were mostly consistent with injection studies by Riquet et al. Direct lymphatic drainage from the esophagus to the thoracic duct was observed in 19% of cadavers (39). Direct lymphatic drainage of lung segments to distant mediastinal nodes is also reviewed. The sentinel node concept is discussed in relation to the above observations.

CONCLUSIONS

We hypothesize that the most critical sentinel node, if such usage is allowed, is situated as a guard for a limited specific route and for a common drainage route. We term it the "common terminal node".

Biology of metastatic disease

Metastasis development is a complex series of events involving the generation of new blood vessels, growth, invasion with breakdown of the host matrix, transport to other sites with adhesion, and subsequent invasion of the organ that hosts the metastasis. It is only recently that the molecular basis for these events has been studied, and the understanding of this process is now leading to the development of therapies that targets one or more of the components of this series of events.

Biology and surgical management of breast cancer

The surgical treatment of breast cancer has been a source of controversy. The controversy arises from the differences in physicians' philosophies regarding the biology of breast carcinoma. Traditionally, surgeons have emphasized the potential therapeutic value of regional lymph node dissection, maintaining that adequate loco-regional treatment is of prime concern in patients with localized tumors. On the other hand, medical oncologists have always stressed the systemic nature of cancer. However, breast cancer is a very heterogeneous disease with an enormous range of different biologic characteristics, and new information is continually becoming available on the natural history of breast cancer. Therefore, we should seek a more rational theory based on the clinical evidence which can explain the biologic characteristics of breast cancer. We have proposed a new spectrum hypothesis as follows: (a)tumor cells traverse lymphatics to lymph nodes by direct extension, and there is an orderly pattern in the early stage of lymph node metastases; (b)regional lymph nodes are able to trap tumor cells but are ineffective or incomplete barriers to tumor cell spread; (c)regional lymph nodes have biologic importance, and a positive lymph node is an indicator of a host-tumor relationship that correlates with the subsequent appearance of distant disease; (d)lymphatic and hematogenous dissemination occur not serially, but in a parallel fashion; (e)many palpable invasive breast cancers are a systemic disease, but non-invasive or minimally invasive breast cancers are likely to be a local disease; (f)early detection and treatment of in-breast cancer improves survival, but variations in regional therapy are unlikely to have a major influence on survival.

History of sentinel node and validation of the technique

Sentinel node biopsy is a minimally invasive technique to select patients with occult lymph node metastases who may benefit from further regional or systemic therapy. The sentinel node is the first lymph node reached by metastasising cells from a primary tumour. Attempts to remove this node with a procedure based on standard anatomical patterns did not become popular. The development of the dynamic technique of intraoperative lymphatic mapping in the 1990s resulted in general acceptance of the sentinel node concept. This hypothesis of sequential tumour dissemination seems to be valid according to numerous studies of sentinel node biopsy with confirmatory regional lymph node dissection. This report describes the history and the validation of the technique, with particular reference to breast cancer.

Transport of colloidal particles in lymphatics and vasculature after subcutaneous injection

This study was designed to determine the transport of subcutaneously injected viral-size colloid particles into the lymph and the vascular system in the hind leg of the dog. Transport of two colloid particles, with average size approximately 1 and 0.41 microm, respectively, and with and without leg rotation, was tested. Leg rotation serves to enhance the lymph flow rates. The right femoral vein, lymph vessel, and left femoral artery were cannulated while the animal was under anesthesia, and samples were collected at regular intervals after subcutaneous injection of the particles at the right knee level. The number of particles in the samples were counted under fluorescence microscopy by using a hemocytometer. With and without leg rotation, both particle sets were rapidly taken up into the venous blood and into the lymph fluid. The number of particles carried away from the injection site within the first 5 min was <5% of the injected pool. Particles were also seen in arterial blood samples; this suggests reflow and a prolonged residence time in the blood. These results show that particles the size of viruses are rapidly taken up into the lymphatics and blood vessels after subcutaneous deposition.

Extended lymph node dissection in gastrointestinal cancer

We reviewed the literature concerning the effect of extended lymph node dissection on survival in patients with gastrointestinal cancer. Most retrospective and/or prospective nonrandomized comparative studies have claimed that extended lymph node dissection significantly improves survival rate in patients with esophageal cancer, gastric cancer, and colorectal cancer. However, it is difficult to interpret these results since specialized care provided in trials may itself improve survival. In gastric cancer, several prospective randomized trials have failed to demonstrate a survival advantage of extended dissection, while there are few well-done prospective randomized trials in esophageal or colorectal cancer. Therefore, the therapeutic value of extended lymph node dissection remains to be determined in gastrointestinal cancer. Randomized prospective studies within the bounds of the ethical treatment of patients can and should be done.

Rates of flow of technetium 99m--labeled human serum albumin from peripheral injection sites to sentinel lymph nodes

BACKGROUND

The new technique of sentinel lymphadenectomy for cutaneous melanoma provided us with a unique opportunity to quantitate the rates of lymphatic flow in afferent lymphatics.

METHODS

Seventeen melanoma patients underwent preoperative lymphoscintigraphy with technetium 99m-human serum albumin (HSA). The time and distance between the injection site and the sentinel lymph node (LN) were recorded. By comparison, lymphatic flow rates between footpad, popliteal LN, femoral LN, and systemic blood were measured in 60 female mice (C57BL/6) after footpad injection of 99mTc-HSA.

RESULTS

The rate of lymphatic flow to 14 axillary, four inguinal, one popliteal, and one parotid sentinel LNs averaged 10.4 +/- 7.3 cm/min. In contrast, the lymphatic flow rate between the footpad and the popliteal LN in mice (analogous to the sentinel LN in human beings) averaged 1.33 +/- 0.52 cm/min. There was a marked delay in the passage of radionuclide through the popliteal LN with consequent slowing of the rate of flow between the popliteal and femoral LNs to 0.22 cm/min.

CONCLUSION

Lymphatic flow to the sentinel LN occurs rapidly from both human skin and murine footpads. This information might be helpful in planning the timing of the incision after vital blue dye injection for identifying the sentinel LN.

Pattern of prostate cancer metastasis to the vertebral column

We examined 34 thoracic and lumbar vertebrae in eight patients with prostate cancer to elucidate the pattern of metastasis to the vertebral column. Computed tomography of thoracic and lumbar vertebrae was performed before treatment for the prostate cancer. Metastatic lesions were confirmed both by the recognition of osteoblastic and/or osteolytic lesions on CT and by histological identification at autopsy. Localized metastatic lesions were observed mostly in the peripheral rather than the central part of the vertebral body. There were no differences in distribution of lesions between the anterior and posterior parts of the vertebral body. There was no primary involvement of tumor in the spinous and transverse processes. These findings indicated that the major metastatic pathway to the vertebral column is via the vertebral venous system, and it appears that prostate cancer cells first metastasize to the vertebral body and then spread secondarily to the processes or other vertebrae.

In vivo selection and characterization of a murine mammary tumor subline with high potential for spontaneous lymph node metastasis

A transplantable mammary adenocarcinoma, grown in Balb/c mice, with a marked enhancement in its draining lymph node metastatic ability (MM3LN), was obtained through an in vivo procedure from a variant tumor moderately metastatic to lymph nodes (MM3). Both MM3 and MM3LN presented a similar latency and tumor growth rate and reached the same tumor mean diameter at death. MM3LN tumor-bearing mice exhibited a larger mean survival time. The new variant showed a 2.5-fold higher incidence of tumor-draining lymph node metastases than MM3 line, with no differences in the incidence of lung metastases. Morphology as well as cytogenetic and in vitro adhesion properties were studied in order to characterize the new subline. This murine tumor model has potential application in the study of the metastatic process in lymphoid tissue.

Spontaneous regional lymph node metastases of three variants of the B16 melanoma: relationship to primary tumor size and pulmonary metastases

We studied the patterns of spontaneous regional lymph node metastases of three variants (F1, F10, and BL6) of the B16 melanoma in C57BL/6 mice and related the incidence to primary tumor size and pulmonary metastases. The incidence of regional lymph node and pulmonary metastases correlated with increasing primary tumor size (p less than or equal to 0.0001). The incidence of pulmonary metastases in mice whose regional lymph nodes did not contain tumor also correlated with increasing primary tumor size (p less than or equal to 0.0001). This propensity for direct hematogenous spread was more apparent in BL6 tumors than in F1 and F10 tumors (p less than or equal to 0.0001). BL6 tumors also metastasized to regional nodes at smaller primary tumor sizes (p less than or equal to 0.04). Heterogeneous variants that metastasize earlier to regional lymphatic and hematogenous sites dictates the natural history of the primary tumor. Whether prophylactic lymphadenectomy for melanomas is therapeutic may depend on dissemination-related phenotypic characteristics.

Role of the regional lymph node in cancer metastasis

At an early phase of tumor growth, T-cell responses, i.e. the proliferation of T cells and the generation of cytotoxic T cells or killer-augmenting T cells are induced in the regional lymph node depending upon the immunological properties of the tumor cells. A small number of tumor cells seems to be rejected in the regional lymph node in situ. A progressive tumor induces suppressor activity in the regional node. Suppressor cells facilitate tumor growth and lead to lymphatic metastasis. Thus, the regional lymph node operates only as a temporary barrier to tumor growth. Experimental studies have demonstrated that eradication of the suppressor cells and effective immunization, or both, lead to tumor rejection by augmenting the immunological activity of the regional lymph node.