Dynamic spatio-temporal patterns of metapopulation occupancy in patchy habitats

Spatio-temporal dynamics in habitat suitability and connectivity among mosaics of heterogeneous wetlands are critical for biological diversity and species persistence in aquatic patchy landscapes. Despite the recognized importance of stochastic hydroclimatic forcing in driving wetlandscape hydrological dynamics, linking such effects to emergent dynamics of metapopulation poses significant challenges. To fill this gap, we propose here a dynamic stochastic patch occupancy model (SPOM), which links parsimonious hydrological and ecological models to simulate spatio-temporal patterns in species occupancy in wetlandscapes. Our work aims to place ecological studies of patchy habitats into a proper hydrologic and climatic framework to improve the knowledge about metapopulation shifts in response to climate-driven changes in wetlandscapes. We applied the dynamic version of the SPOM (D-SPOM) framework in two wetlandscapes in the US with contrasting landscape and climate properties. Our results illustrate that explicit consideration of the temporal dimension proposed in the D-SPOM is important to interpret local- and landscape-scale patterns of habitat suitability and metapopulation occupancy. Our analyses show that spatio-temporal dynamics of patch suitability and accessibility, driven by the stochasticity in hydroclimatic forcing, influence metapopulation occupancy and the topological metrics of the emergent wetlandscape dispersal network. D-SPOM simulations also reveal that the extinction risk in dynamic wetlandscapes is exacerbated by extended dry periods when suitable habitat decreases, hence limiting successful patch colonization and exacerbating metapopulation extinction risks. The proposed framework is not restricted only to wetland studies but could also be applied to examine metapopulation dynamics in other types of patchy habitats subjected to stochastic external disturbances.

The role of radioactive iodine in the management of patients with differentiated thyroid cancer - An oncologic surgical perspective

With improved understanding of the biology of differentiated thyroid carcinoma its management is evolving. The approach to surgery for the primary tumour and elective nodal surgery is moving from a "one-size-fits-all" recommendation to a more personalised approach based on risk group stratification. With this selective approach to initial surgery, the indications for adjuvant radioactive iodine (RAI) therapy are also changing. This selective approach to adjuvant therapy requires understanding by the entire treatment team of the rationale for RAI, the potential for benefit, the limitations of the evidence, and the potential for side-effects. This review considers the evidence base for the benefits of using RAI in the primary and recurrent setting as well as the side-effects and risks from RAI treatment. By considering the pros and cons of adjuvant therapy we present an oncologic surgical perspective on selection of treatment for patients, both following pre-operative diagnostic biopsy and in the setting of a post-operative diagnosis of malignancy.

Role of ancillary techniques in profiling unclassified laryngeal malignancies

Laryngeal biopsies, contrary to biopsies from many other sites of the body, very often contain minute amounts of tumour tissue that may consist of morphologically undifferentiated tumour only. In haematoxylin- and eosin-stained sections, there may be no indicative features of what specific tumour entity that is present. In the larynx, particularly small round cell neoplasms, primary or metastatic, often cause a diagnostic dilemma and where an incorrect diagnosis can induce substantial clinical consequences for the patient (e.g., primary neuroendocrine carcinomas vs metastatic variants, certain sarcomas). If sufficient/representative material has been obtained, the application of immunohistochemistry and/or molecular techniques should in virtually every case reveal the true nature of the malignancy. In cases with sparse amount of material, and therefore a limited number of sections to be cut, a careful and thoughtful stepwise approach is necessary to ascertain a reliable diagnosis, or at least guide the clinician to the most likely diagnoses. With today's advanced and widely available technology with an abundance of markers to discriminate different tumours, the use of the term "undifferentiated" should be largely unnecessary. In the exceptional, and indeed exceedingly rare cases, when a classification is not possible, even after repeat biopsy, we suggest that the laryngeal neoplasm is better termed "unclassified malignant neoplasm" rather than "undifferentiated malignant neoplasm".

Trismus in patients with head and neck cancer: etiopathogenesis, diagnosis and management

BACKGROUND

Trismus indicates severely restricted mouth opening of any aetiology. A mouth opening of 35 mm or less should be regarded as trismus. Aim of this study was to review the etiopathogenesis, incidence, treatment and prevention of trismus in patients with head and neck cancer.

OBJECTIVE OF REVIEW

Trismus is frequently seen in patients suffering from malignant tumours of the head and neck. The reported prevalence of trismus in those patients varies considerably in the literature and ranges from 0 to 100% depending on the tumour site and extension. Trismus may worsen or remain the same over time, or the symptoms may reduce, even in the absence of treatment. When a patient presents with trismus after tumour treatment, it is important to determine whether the trismus is the result of the treatment, or is the first sign of a recurrence. Restricted mouth opening may impede inspection of the oral cavity as needed for dental care, and particularly for oncologic follow-up.

CONCLUSIONS

Mouth opening after radiotherapy (RT) decreases on average by approximately 20% compared to mouth opening prior to RT. The prevalence of trismus increases with increasing doses of RT to mastication structures. The use of intensity-modulated RT seems to lower the percentage and severity of RT-induced trismus. Treatment of trismus can be conservative (with either medical or physical therapy) or surgical. Exercise therapy is the mainstay of treatment and exercise should start as soon as possible after treatment. The prevention of trismus, rather than its treatment, is the most important objective.

The impact of family history on non-medullary thyroid cancer

INTRODUCTION

Around 10% of patients with non-medullary thyroid cancer (NMTC) will have a positive family history for the disease. Although many will be sporadic, families where 3 first-degree relatives are affected can be considered to represent true familial non-medullary thyroid cancer (FNMTC). The genetic basis, impact on clinical and pathological features, and overall effect on prognosis are poorly understood.

METHODS

A literature review identified articles which report on genetic, clinical, therapeutic and screening aspects of FNMTC. The results are presented to allow an understanding of the genetic basis and the impact on clinical-pathological features and prognosis in order to inform clinical decision making.

RESULTS

The genetic basis of FNMTC is unknown. Despite this, significant progress has been made in identifying potential susceptibility genes. The lack of a test for FNMTC has led to a clinical definition requiring a minimum of 3 first-degree relatives to be diagnosed with NMTC. Although some have shown an association with multi-centric disease, younger age and increased rates of extra-thyroidal extension and nodal metastases, these findings are not supported by all. The impact of FNMTC is unclear with all groups reporting good outcome, and some finding an association with more aggressive disease. The role of screening remains controversial.

CONCLUSION

FNMTC is rare but can be diagnosed clinically. Its impact on prognostic factors and the subsequent role in influencing management is debated. For those patients who present with otherwise low-risk differentiated thyroid cancer, FNMTC should be included in risk assessment when discussing therapeutic options.

Salivary acinic cell carcinoma: reappraisal and update

Epidemiologic and clinicopathologic features, therapeutic strategies, and prognosis for acinic cell carcinoma of the major and minor salivary glands are critically reviewed. We explore histopathologic, histochemical, electron microscopic and immunohistochemical aspects and discuss histologic grading, histogenesis, animal models, and genetic events. In the context of possible diagnostic difficulties, the relationship to mammary analog secretory carcinoma is probed and a classification is suggested. Areas of controversy or uncertainty, which may benefit from further investigations, are also highlighted.

On species persistence-time distributions

We present new theoretical and empirical results on the probability distributions of species persistence times in natural ecosystems. Persistence times, defined as the timespans occurring between species' colonization and local extinction in a given geographic region, are empirically estimated from local observations of species' presence/absence. A connected sampling problem is presented, generalized and solved analytically. Species persistence is shown to provide a direct connection with key spatial macroecological patterns like species-area and endemics-area relationships. Our empirical analysis pertains to two different ecosystems and taxa: a herbaceous plant community and a estuarine fish database. Despite the substantial differences in ecological interactions and spatial scales, we confirm earlier evidence on the general properties of the scaling of persistence times, including the predicted effects of the structure of the spatial interaction network. The framework tested here allows to investigate directly nature and extent of spatial effects in the context of ecosystem dynamics. The notable coherence between spatial and temporal macroecological patterns, theoretically derived and empirically verified, is suggested to underlie general features of the dynamic evolution of ecosystems.

Modelling cholera epidemics: the role of waterways, human mobility and sanitation

We investigate the role of human mobility as a driver for long-range spreading of cholera infections, which primarily propagate through hydrologically controlled ecological corridors. Our aim is to build a spatially explicit model of a disease epidemic, which is relevant to both social and scientific issues. We present a two-layer network model that accounts for the interplay between epidemiological dynamics, hydrological transport and long-distance dissemination of the pathogen Vibrio cholerae owing to host movement, described here by means of a gravity-model approach. We test our model against epidemiological data recorded during the extensive cholera outbreak occurred in the KwaZulu-Natal province of South Africa during 2000-2001. We show that long-range human movement is fundamental in quantifying otherwise unexplained inter-catchment transport of V. cholerae, thus playing a key role in the formation of regional patterns of cholera epidemics. We also show quantitatively how heterogeneously distributed drinking water supplies and sanitation conditions may affect large-scale cholera transmission, and analyse the effects of different sanitation policies.

Paraneoplastic syndromes in patients with oral cancer

The diagnosis of a paraneoplastic syndrome (PNS) may precede, follow or be concurrent with the diagnosis of a malignant tumor. There is increasing knowledge of association between PNS and head and neck cancers, but the relationship between oral cancer and paraneoplastic disease has not been previously investigated. PNS associated with head and neck cancer can be divided into six main groups: endocrine, cutaneous or dermatologic, hematologic, osteoarticular or rheumatologic, neurologic, and ocular syndromes. We have comprehensively reviewed the literature to evaluate the incidence of occurrence of PNS with oral cancer, and conclude that only endocrine and dermatologic PNS have been associated with oral cancer. Humoral hypercalcemia is the most frequent PNS related to oral cancer, and has a negative prognostic significance. Dermatologic PNS are less common, but when they occur, they may precede the diagnosis of the oral tumor. Awareness of these conditions is important for clinicians who deal with cancer.

Inferring plant ecosystem organization from species occurrences

In this paper, we present an approach capable of extracting insights on ecosystem organization from merely occurrence (presence/absence) data. We extrapolate to the collective behavior by encapsulating some simplifying assumptions within a given set of constraints, and then examine their ecological implications. We show that by using the mean occurrence and co-occurrence of species as constraints, one is able to capture detailed statistics of a plant community distributed across a vast semiarid area of the United States. The approach allows us to quantify the species' effective couplings: Their frequencies exhibit a peak at zero and the minimal pairwise model is able to capture about 80% of the ecosystem structure. Our analysis reveals a relatively stronger impact of the species network on uncommon species and underscores the importance of species pairs experiencing positive couplings. Additionally, we study the associations among species and, interestingly, find that the frequencies of groups of different species, which the approach is able to capture, exhibit a power-law-like distribution.

On spatially explicit models of cholera epidemics

We generalize a recently proposed model for cholera epidemics that accounts for local communities of susceptibles and infectives in a spatially explicit arrangement of nodes linked by networks having different topologies. The vehicle of infection (Vibrio cholerae) is transported through the network links that are thought of as hydrological connections among susceptible communities. The mathematical tools used are borrowed from general schemes of reactive transport on river networks acting as the environmental matrix for the circulation and mixing of waterborne pathogens. Using the diffusion approximation, we analytically derive the speed of propagation for travelling fronts of epidemics on regular lattices (either one-dimensional or two-dimensional) endowed with uniform population density. Power laws are found that relate the propagation speed to the diffusion coefficient and the basic reproduction number. We numerically obtain the related, slower speed of epidemic spreading for more complex, yet realistic river structures such as Peano networks and optimal channel networks. The analysis of the limit case of uniformly distributed population sizes proves instrumental in establishing the overall conditions for the relevance of spatially explicit models. To that extent, the ratio between spreading and disease outbreak time scales proves the crucial parameter. The relevance of our results lies in the major differences potentially arising between the predictions of spatially explicit models and traditional compartmental models of the susceptible-infected-recovered (SIR)-like type. Our results suggest that in many cases of real-life epidemiological interest, time scales of disease dynamics may trigger outbreaks that significantly depart from the predictions of compartmental models.

Paraneoplastic syndromes in patients with nasopharyngeal cancer

Paraneoplastic syndromes (PNS) represent the clinical manifestation of the remote and indirect effects produced by tumor metabolites or other products. Paraneoplastic effects are not directly mediated by tumor invasion of normal tissue, or by the disruption of normal function of the involved organ, or by distant metastases. More than 260 cases of nasopharyngeal carcinoma (NPC) associated with PNS have been reported in the literature. These syndromes can be divided into six main groups: cutaneous or dermatologic, endocrine, hematologic, osteoarticular or rheumatologic, neurologic, and ocular. The most common dermatologic manifestation is dermatomyositis, while the syndrome of inappropriate secretion of antidiuretic hormone and occasionally Cushing's syndrome due to ectopic ACTH production are the endocrinologic manifestations. Tumor fever and leukemoid reaction, osteoarticular or rheumatic syndromes, including clubbing of the fingers and toes, sensory neuropathy and demyelinating motor polyneuropathy, and rarely optic neuritis represent the most prominent examples of the other groups of syndromes. PNS may occur before the NPC is manifest, or while it is in an occult stage, and thus the possibility of NPC should be considered in patients with these various disorders. While some PNS will respond to direct treatment, most often the PNS subsides in parallel to response of the NPC, and thus may be useful for monitoring tumor response or recurrence.

Role of limited parotidectomy in management of pleomorphic adenoma

There is continued controversy over the extent of parotidectomy required for removal of a benign pleomorphic adenoma from the parotid gland. Currently, consensus exists that the integrity of the facial nerve must be preserved when the tumour is totally removed.

As a result of experience gained in the first half of the twentieth century, it was recommended that superficial parotidectomy with facial nerve dissection should be the minimal biopsy for pleomorphic adenoma. Since that time, however, research has indicated that partial parotidectomy or extracapsular dissection of benign pleomorphic adenoma can be accomplished with preservation of the facial nerve without an increase in tumour recurrence. Partial parotidectomy or extracapsular dissection results in impaired cosmetic results and a lower incidence of Frey's syndrome, and thus may be the preferred approach when undertaken by experienced surgeons.

A historical review of head and neck cancer in celebrities

Introduction: The illnesses of celebrity patients always receive more attention from the general public than those of ordinary patients. With regard to cancer, this fact has helped to spread information about the four major malignancies: breast cancer, prostatic cancer, lung cancer and colorectal cancer. Head and neck cancer, on the other hand, is still not well recognised by the lay public, although the risk factors are similar to those of lung cancer. It was the objective of this analysis to identify cases of celebrity patients, the description of which could help to increase awareness of head and neck cancer, its symptoms and risk factors.

Methods: The Internet and medical literature databases were searched for celebrity patients who had suffered from head and neck cancer.

Results: The search revealed numerous famous head and neck cancer patients. However, only seven cases were documented well in the medical literature. Among the identified persons were one emperor, two United States presidents, a legendary composer, a world-renowned medical doctor, an outstanding athlete and an extraordinary entertainer. In spite of their exclusive position in society, these patients did not have a better prognosis compared with ordinary patients of their time. Only two of the group experienced long term survival and only one was cured. None of these influential figures used their influence to fund research or to promote knowledge about their respective diseases.

Conclusion: The identified cases could help increase public awareness of head and neck cancer. Similar to activities in other oncologic fields, current celebrity head and neck cancer patients should be encouraged to discuss their diseases openly, which could have a positive effect on public health.

The incidence of lymph node micrometastases in patients pathologically staged N0 in cancer of oral cavity and oropharynx

The presence of nodal metastasis in head and neck cancer is an important prognostic factor and crucial in making critical decisions regarding postoperative radiation treatment and follow up. The final documentation of nodal metastasis is still based on routine histopathological evaluation of the lymph nodes in the neck. The newer technologies including immunohistochemistry, molecular analysis and subserial sectioning may increase the detection of lymph node micrometastases in patients pathologically staged N0 in cancer of oral cavity and oropharynx.

The treatment of distant metastases in head and neck cancer--present and future

At the present time the occurrence of distant metastases in patients with head and neck squamous cell carcinoma means that lifespan is measured in months. In most instances treatment is purely palliative. Isolated lung metastasis can be successfully removed with long-term disease control in selected patients. Radiotherapy can be useful for palliation of bone metastases and occasionally lung or brain metastases. Chemotherapy does not have a major impact at the present time except for the treatment of metastases from nasopharyngeal cancer. Palliative symptomatic care, along with appropriate pain control, is essential since pain management is very important in these patients. A significant change in the survival of patients with head and neck cancer is only likely to occur by the development of new approaches to treatment. Blocking tumor angiogenesis and treatment based on genetic abnormalities or cell surface receptors offer the two strategies that are most likely to be successful.

Distant metastases from thyroid and parathyroid cancer

Thyroid cancer represents a unique biological tumor where even with the high incidence of distant metastases, the overall prognosis is not as poor as many other human cancers. The overall long-term survival in patients presenting initially with distant metastasis is approximately 50%. The overall incidence of distant metastases varies between 10 and 35%, depending upon the histology. The overall incidence is directly related to various histologies - being least in papillary thyroid carcinoma (10%) and highest in Hürthle cell tumor (33%). The incidence of distant metastases is also very high in patients with medullary and anaplastic thyroid cancer. The incidence of distant metastases at the time of initial presentation in differentiated thyroid cancer is approximately 4%. In high-risk patients - especially in patients with extrathyroidal extension or massive nodal metastasis - the distant metastases can be evaluated after total thyroidectomy with radioactive iodine ablation. Pulmonary metastases are very common in young individuals, but they are extremely well treated and the mortality from distant metastases in this group is very low. However, distant metastases in patients with poorly-differentiated carcinoma have a poor prognosis. In high-risk patients, generally a total thyroidectomy should be undertaken so that the patient can undergo radioactive iodine dosimetry and ablation as indicated. The surveillance in patients with thyroid cancer includes: close clinical follow-up, chest X-ray, and radioactive iodine dosimetry. Thyroglobulin is commonly used as a prognostic marker in patients having undergone total thyroidectomy. The incidence of distant metastases in medullary thyroid cancer is high, mainly to the lung and liver. Persistent hypercalcitonemia is an indication of regional or distant metastases. A variety of diagnostic tests are helpful, such as octreotide scanning, computed tomography scan, magnetic resonance imaging and positron emission tomography scan. Laparoscopy to evaluate the surface of the liver is also an important investigation to detect distant metastases. The incidence of distant metastases is very high in patients with anaplastic thyroid cancer, but most of the time the outcome depends on the locoregional recurrence and massive disease in the central compartment. The parathyroid cancer is quite rare, less than 1%, in patients undergoing parathyroidectomy. The diagnosis of parathyroid cancer is made by pathological features but the most certain method of diagnosis of a malignant tumor of the parathyroid is the identification of secondary deposits. The incidence of distant metastasis is difficult to determine due to the rarity of this condition, but the most common site is the lung. Patients with distant metastasis have recurrent progressive hypercalcemia along with high parathormone level.

General considerations on distant metastases from head and neck cancer

Mortality in head and neck cancer is due to locoregional disease, distant metastases or intercurrent disease. As treatment of the primary tumor and cervical metastases has improved, the proportion of deaths from co-morbidity and from distant metastases has increased. Distant metastases almost invariably herald a poor prognosis in head and neck cancer with an average survival of 4.3-7.3 months and treatment is usually palliative. Reliable detection is important to prevent inappropriate treatment. The risk is related to the site, stage and histology of the primary tumor and the presence of cervical metastases. Early detection and treatment of cervical metastases may prevent distant metastases. Accurate staging of tumors helps to identify high-risk tumors that should be specifically investigated for distant metastases.

Screening tests to evaluate distant metastases in head and neck cancer

Investigation for distant metastases is part of the staging process of a primary tumor or recurrent disease before treatment. The lung is the most frequent site followed by bone and liver. Advanced stage and cervical metastases are the most important predictors of metastases. Almost all distant metastases are associated with lung metastases. Computed tomography scan of the chest is the single most effective investigation. The value of routine screening tests is questionable and merits further investigation.

Incidence and sites of distant metastases from head and neck cancer

The incidence of distant metastases in head and neck squamous cell carcinoma (SCC) is relatively small in comparison to other malignancies. Distant metastases adversely impact survival and may significantly affect treatment planning. The incidence of distant metastases is influenced by location of the primary tumor, initial T and N stage of the neoplasm, and the presence or absence of regional control above the clavicle. Patients with advanced nodal disease have a high incidence of distant metastases, particularly in the presence of jugular vein invasion or extensive soft tissue disease in the neck. Primary tumors of advanced T stages in the hypopharynx, oropharynx and oral cavity are associated with the highest incidence of distant metastases. Pulmonary metastases are the most frequent in SCC, accounting for 66% of distant metastases. It may be difficult to distinguish pulmonary metastasis from a new primary tumor, particularly if solitary. Other metastatic sites include bone (22%), liver (10%), skin, mediastinum and bone marrow. An important question remains as to how intensely pre- and postoperative screening for distant metastases should be performed. Preoperative chest X-ray is warranted in all cases. If the primary tumor and nodal status place the patient at high risk for pulmonary metastasis, then preoperative computed tomography scan of the chest should be done. Screening for distant metastases at other sites is usually not indicated in SCC of the upper aerodigestive tract. Postoperatively, annual X-rays of the chest are usually sufficient, but in high-risk situations a chest X-ray performed every 3-6 months may be beneficial. Certain histologic types of primary tumor have greater or lesser propensity to metastasize distantly, and have a different natural history. Adenoid cystic carcinoma metastasizes frequently, even in the absence of extensive local or regional disease. Basaloid squamous cell carcinoma and neuroendocrine carcinomas also metastasize widely. Extensive evaluation for distant metastases is justified for these tumors. Knowledge of the natural history of various neoplasms and the factors that contribute to distant metastases as well as good judgement are essential for cost-effective treatment planning and decision-making with regard to pre- and postoperative evaluation for distant metastases in cancer of the head and neck.

The sentinel node procedure with Patent Blue V dye in the surgical treatment of papillary thyroid carcinoma

How far to extend the surgical treatment of papillary thyroid carcinoma (PTC) is still an open question. A contribution may come from intra-operative lymphatic mapping because, in other malignancies, the procedure has become an important aid in defining lymph node status. To assess the feasibility of using the sentinel lymph node (SLN) technique with the intratumoral injection of Patent Blue V dye to guide nodal dissection in PTC, 29 patients with a preoperative diagnosis of PTC and no clinical or ultrasonographic evidence of nodal involvement underwent cervicotomy and exposure of the thyroid gland, followed by Patent Blue V dye injection into the thyroid nodule. Total thyroidectomy was subsequently performed, resecting the lymph nodes at levels III, IV, VI and VII. The thyroid, SLN and the other lymph nodes were snap-frozen and submitted for both intra-operative and subsequent definitive pathological evaluation. Intra-operative lymphatic mapping located the SLN in 22/29 patients (75.9%) and the SLN revealed neoplastic involvement in 4/22 (18.2%); other lymph nodes were also positive in 2 cases. In the 18 patients whose SLNs were not metastatic, the other nodes were also disease-free. The SLN technique thus seems helpful in avoiding unnecessary lymph node dissection in PTC without spread to the SLN.

Surgical management of the neck in thyroid cancer

Thyroid cancer is a relatively common clinical problem. The American Cancer Society has estimated 1,050,000 newly diagnosed cancers in 1999 in the United States, of which 16,000 are expected to be of thyroid origin. Although most thyroid cancers have an excellent prognosis as compared with other malignant tumors, it is estimated that approximately 1,225 deaths will be attributed to the disease [1].

The pathology and clinical features of "glue ear": a review

The clinical entity known as "glue ear" is synonymous with mucoid otitis media and represents the most common cause of hearing loss in children. This review considers the current state of our knowledge of mucoid otitis media, discussing definition and terminology, pathology, etiology and microbiology, clinical features, differential diagnosis and treatment.

What is the incidence of occult metastasis in patients with stage N(0) cancers of the head and neck?

There is a large body of evidence in the European and US literature which argues forcefully that the presence of metastatic deposits within cervical lymph nodes is the single most significant independent adverse prognostic factor in patients with squamous-cell carcinomas of the head and neck. When all head and neck cancers are considered, ipsilateral lymph node metastases appear to decrease patient survival by as much as 50%; moreover, the presence of contralateral or bilateral cervical metastases reduces prognosis by an additional 50%. Patients with cervical metastases seem to be more likely to develop both distant metastases and local recurrences at the primary site.

The pathology and management of subglottic cancer

Because there is still considerable controversy concerning the anatomical boundaries separating the three regions of the larynx, cancer of the subglottis remains difficult to manage. We have reviewed the numerous differences in the anatomical definitions used in the literature and the consequent differences in reported findings on the incidence of subglottic cancer and its classification. We have also summarized the pathology of subglottic malignant neoplastic lesions, their presenting symptoms and tendency for spread, and the use of imaging methods in its diagnosis. Suitable forms of treatment are discussed, as are considerations on prognosis.

Is extended selective supraomohyoid neck dissection indicated for treatment of oral cancer with clinically negative neck?

Oral cavity tumors may develop occult metastases to the cervical lymph nodes. Current imaging techniques and routine histopathologic methods may fail to detect lymph node micrometastases, but the surgeon has to electively dissect a neck at risk of developing clinical disease. Supraomohyoid neck dissection has been the elective surgery for treating a clinically negative neck in patients with oral cavity primaries. A literature review revealed that level IV nodes can be significantly affected by occult disease with and without metastases in level I-III lymph nodes. This means that level IV nodes have to be included in the supraomohyoid neck dissection, resulting in a more extensive surgical procedure to ensure a margin of oncological safety.