[Sino-nasal inverted papillomas and occupational etiology]

The sino-nasal inverted papilloma is a rare benign tumour with certain aggressive features because of frequent relapses and the high probability of malignant degeneration. For these reasons, several studies have been made to evaluate the efficacy of the different courses of treatment, but only afew studies have been carried out to establish the etiology of this tumour, which is still uncertain. Although it is believed that viral infection, chronic inflammation and cigarette smoking can play an important etiological role, it has recently been suggested that occupational risk factors, such as those involved in malignant epithelial sino-nasal cancer (SNC), can also be involved in causing sino-nasal inverted papilloma. A group of 70 patients was examined who have been diagnosed with inverted papilloma from 1991 to 2003; the occupational history, collected via the standardized questionnaire, showed that risk factors like wood and leather dusts, chromium and nickel vapours or fumes and formaldehyde were associated with only 5% of all cases. This proportion is much lower than that established for SNC in several epidemiological studies. Although occupational environmental pollution can be a source of chronic sino-nasal mucosa irritation, on the basis of our results we believe that a causal relationship between exposure to occupational risk factors and inverted papilloma is not likely, differently from the suggestions made in other studies. Consequently, an epidemiological surveillance of inverted papilloma as a "sentinel" tumour, as has been proposed in Italy for SNC, is not considered necessary. Among the possible non-occupational risk factors we observed that 75% of the male patients were smokers and 40% of all patients suffered from chronic sinusitis and sino-nasal polyps. Lastly, among the 70 cases of inverted papilloma, we observed 5 with malignant degeneration.

Radiation-induced malignancy of the head and neck

OBJECTIVE

Our goal was to evaluate our experience with radiation-induced malignancy (RIM), compare that experience to the literature, and review treatment modalities.

STUDY DESIGN AND SETTING

The setting is the University of Kansas Medical Center. A retrospective review was performed to identify patients with RIM. Patients were included if they met the criteria for RIM as delineated in the literature.

RESULTS

Thirteen patients met the criteria for RIM. The mean latency period was 22 years. Sarcomas were the most common type of RIM and the paranasal sinuses were the most common location. Surgical resection was our treatment of choice.

CONCLUSIONS

Our patient series differs from previous reports in that sarcomas were the predominating RIM and the paranasal sinuses were the most common location. We noted a shorter latency period than has been previously published. Surgical excision is the treatment of choice.

EBM RATING

C.

[Epithelial naso-sinusal cancer incidence and the role of work in 100 cases diagnosed in the Province of Brescia (northern Italy), in the period 1978-2002]

BACKGROUND

Naso-sinusal cancers (NSC) cover a group of rare tumours in Italy for which the role of occupational risk has been established. The systematic survey of NSC in the province of Brescia made it possible to analyse the jobs of the cases occurring in the area.

OBJECTIVES

The aims of the research were: estimation of epithelial NSC incidence both in the general population and among wood and leather workers, description of the frequency and type of occupational exposure to substances or manufacturing processes.

METHODS

The epithelial type cases were obtained from the Naso-sinusal Cancer Register (population-based) operating in the Province of Brescia since 1994. Work histories were obtained via a standardized questionnaire.

RESULTS

The annual incidence ofepithelial NSC (for 100,000) in the entire population (1,090,000 inhabitants, ISTAT census 1991) from 1993 to 1997 and from 1998 to 2002 was nearly the same, 0.82 and 0.90 for men, 0.37 and 0.37 for women, respectively. The nasal cavity was the most affected anatomic site (45%) and squamous cell carcinoma was the most frequent histotype (44%) among the first 100 cases whose case histories were appropriate; in the ethmoidal sinus adenocarcinoma represented 62% of the cases; 25% of all cases were exposed to occupational carcinogens (list A) and particularly to wood dust (17%), even if only of softwood species (30%), and leather dusts (7%) especially in the shoe repair. The average latency period was 47 years (SD 7.4) and 44 years (SD 5.6) respectively; 71% of these epithelial NSC cases involved the ethmoid and 85% were adenocarcinomas. Only 1% of the cases was exposed to chromium and nickel and occurred in galvanization processes. Among the exposures to occupational risks with limited epidemiological evidence (list B) there was one case exposed to formaldehyde and 42 cases occurring in the building, agricultural, metallurgic and textile sectors. Thus all the exposures to occupational risks, both certain and probable (lists A and B) reached 84% among men and 17% among women. Epithelial NSC annual incidence rates (for 100,000) estimated among the wood and leather workers for the period 1985-2002 were 13 and 6.5 respectively.

CONCLUSION

The results confirm the meaning of sentinel event for these tumours in occupational health and justify maintaining an active surveillance programme for the cases occurring in the area.

[A review of epidemiologic data on cancers of the nose and paranasal sinuses in Turkey]

OBJECTIVES

To review epidemiologic data on cancers of the nose and paranasal sinuses in Turkey.

PATIENTS AND METHODS

The epidemiologic findings were obtained from the following sources: Cancer Registry (1995 to 1999) of the Department of Cancer Control of the Ministry of Health; records of Izmir Cancer Registry (1993-1994); Prof. Dr. Nazmi Bilir's review in 1977, in which the findings of pathology laboratories were collected; records of cancers of the nose and paranasal sinuses from 1964 to 2000 at the Otolaryngology Department of Medicine Faculty of Hacettepe University.

RESULTS

During the above-mentioned years, cancers of the nose and paranasal sinuses were detected in 127 patients (85 males, 42 females; mean age 47 years; range 1-89 years) in Hacettepe University, of whom 14 were children. The male to female ratio was 2.02. In Nazmi Bilir's review, cancers of the nose and paranasal sinuses were reported in 65 males and 37 females, with a frequency of 0.7% in males and 0.6% in females among all cancers. Its incidence was 0.4/100.000 for males and 0.2/100.000 for females, which was the same as that found in Izmir Cancer Registry. According to the Cancer Registry of the Ministry of Health, cancers of the nose and paranasal sinuses were most commonly encountered at the ages of 50 to 70 years, and were most common in the Marmara region followed by the Middle Anatolia region.

CONCLUSION

Registry systems in our country need to be improved in order to derive more accurate epidemiologic data concerning cancers of the nose and paranasal sinuses.

Mucinous intestinal type adenocarcinoma of the sinonasal tract secondary to passive wood dust inhalation: case report

A 76-year-old female patient with a mucinous intestinal type adenocarcinoma of the sinonasal tract is described. The probable aetiology of passive hard wood dust inhalation, investigations carried out and subsequent surgical treatment using a transfacial access approach and a temporoparietal fascial composite free flap in conjunction with free auricular cartilage are described.

[Nasal sinus carcinoma after wood dust exposure. Morphological spectrum of 100 cases]

Sinonasal carcinomas are usually of the squamous cell or transitional cell type. Adenocarcinomas of the inner nose and the paranasal sinus correlate with exposure to wood dust. However, this is only true for adenocarcinomas of the intestinal type and not for salivary gland carcinomas or polymorphous low-grade adenocarcinomas. Of 160 cases with a history of wood dust exposure and malignant tumors of the inner nose, 134 were sinonasal adenocarcinomas of the intestinal type (SNAIT). In addition, there were 24 other carcinomas as well as 1 malignant melanoma and 1 malignant synovial tumor. The SNAIT showed various subtypes with great morphological similarities to colorectal adenocarcinomas (papillary tubular cylinder cell: 72.4%; alveolar goblet cell: 5.2%; signet ring cell: 3.7%; transitional type: 18.7%). Highly differentiated adenocarcinomas (G1) and mucinous adenocarcinomas were relatively frequent: they accounted for 23.1% and 29.1% of the 134 SNAIT, respectively. Apart from wood dust, wood additives are discussed as a carcinogenic factor. With the development of SNAIT, a metaplasia-dysplasia-carcinoma in situ sequence is probable. If the clinical course shows few symptoms, the first manifestation of such a tumor often occurs in an advanced stage.

New aspects of pathogenesis of juvenile angiofibroma

For over 150 years the aetiology of juvenile angiofibroma has been addressed in numerous theories, but actual details remained unknown. Interesting new findings, reviewed here, are beginning to elucidate the aetiology of this fascinating tumour.

[Health surveillance audit of wood dust exposure]

BACKGROUND

Medical surveillance of wood-dust exposed workers has been compulsory in Italy since 1956. The Law 66 of 25/2/2000, as a consequence of the EU Directive regarding occupational carcinogenic and mutagenic agents, has recently enforced preventive measures for wood dust exposure.

OBJECTIVES

The Local Health Unit RM-F, Civitavecchia, has developed a Workplace Vigilance Plan, specifically aimed at the enhancement of preventive measures against carcinogens. The Plan includes the "audit" of the Occupational Health physicians responsible for workers' surveillance.

METHODS

Physicians are invited to revise the quality of their work and to consider the inclusion of specific occupational health measures in the health plan, such as rhinoscopic examination.

RESULTS

In many cases, this action leads to the revision of the Security Document, the improvement of programs and protocols, and the enhancement of training activities. In a few cases, medical surveillance allowed diagnosis of wood dust-related occupational diseases, such as nasal polyposis and adenocarcinoma of paranasal sinuses.

CONCLUSIONS

Audit in occupational medicine is a feasible and efficient tool to improve quality of health care.

Case-control study evaluating the homogeneity and heterogeneity of risk factors between sinonasal and nasopharyngeal cancers

Sinonasal cancer and nasopharyngeal cancer may share some risk factors because both are located within the upper aerodigestive tract. They may also have different etiological profiles because of anatomic or pathologic differences. However, the similarities and differences in risk factors have rarely been studied within the same population. We assessed the risk factor profiles of sinonasal and nasopharyngeal cancers, using data from a case-control study. The 2 case groups consisted of men aged 31-59 and diagnosed pathologically with sinonasal cancer (n=70) and nasopharyngeal cancer (n=113), respectively. Controls were men without these cancers and selected from the same areas (n=1910). Logistic regression analysis showed that smoking was a risk factor for both sinonasal [odds ratio (OR)=2.5, 95% confidence interval (CI) 1.1-5.4] and nasopharyngeal cancer (OR=1.8, 95%CI 1.1-3.0). However, ever use of barbiturates without a prescription (OR=4.9, 95%CI 1.7-13.8), working with or around cutting oils on a job (OR=1.9, 95%CI 1.1-3.1) and ever having had sinus infections (OR=2.3, 95%CI 1.1-4.6) were associated with nasopharyngeal cancer only. Having received blood products other than a transfusion (OR=9.1, 95%CI 2.2-37.4) and exposure to a pesticide containing 2,4,5-T (OR=5.9, 95%CI 1.5-23.7) were related to sinonasal cancer only. When data analyses were confined to squamous cell type, smoking and exposure to chlorophenols were related to squamous cell tumors at both sites. However, use of barbiturates and sinus problems other than infection only increased the risk of nasopharyngeal carcinoma. Our study suggests that except for smoking and chlorophenol exposure, which are associated with both sites, the risk factor profiles may differ between sinonasal and nasopharyngeal cancers.

[Occupational exposure to wood dust. Health effects and exposure limit values]

This article presents a review of the health effects of occupational exposure to wood dusts and of the data that could be used for setting occupational exposure limits for this nuisance. The causal role of wood dust in the onset of sinonasal cancers is solidly established by numerous epidemiological studies, and the magnitude of the risk is particularly high for adenocarcinoma induced by exposure to hardwood dust. However, no current data allows to rule out the carcinogenic role of softwood dusts and, in the view of protecting the health of the workers, it does not seem relevant to distinguish these two types of wood. Various impairments of the lung function have been frequently associated with exposure to both 'allergenic' and 'non-allergenic' wood dusts and may occur at very low concentrations. According to the SUMER 94 and CAREX studies, about 200 000 workers are currently exposed to wood dusts in France (about 1% of the working population between 1990 and 1994). When taking into account full professional careers, the percentage of workers having been occupationally exposed can be estimated to be about 15% for men and 5% for women. Measurements performed in France between 1987 and 2000 show that exposure levels are high, about 50% of the samplings being over 1mg/m(3) (actual TWA in France). Although the studies present limits, particularly for the quantitative assessment of individual exposure levels, it seems that nonmalignant effects are susceptible to arise at the level of 1mg/m(3); a limit value of 0.5mg/m(3) would credibly allow to protect exposed workers from most of the risks of nonmalignant pulmonary effects. However, it is impossible to assure that this value will avoid the induction of sinonasal cancer, even if this level is certainly lower than the levels to which the cases of sinonasal cancers published in the literature were exposed.

Sinonasal cancer and occupational exposures: a pooled analysis of 12 case-control studies

OBJECTIVE

In order to examine the associations between sinonasal cancer and occupational exposures other than wood dust and leather dust, the data from 12 case-control studies conducted in seven countries were pooled and reanalyzed.

METHODS

The pooled data set included 195 adenocarcinoma cases (169 men and 26 women), 432 squamous cell carcinomas (330 men and 102 women), and 3136 controls (2349 men and 787 women). Occupational exposures to formaldehyde, silica dust, textile dust, coal dust, flour dust, asbestos, and man-made vitreous fibers were assessed with a job-exposure matrix. Odds ratios (ORs) were adjusted for age, study, wood dust, and leather dust, or other occupational exposures when relevant. 95% confidence intervals (CIs) were estimated by unconditional logistic regression.

RESULTS

A significantly increased risk of adenocarcinoma was associated with exposure to formaldehyde. The ORs for the highest level of exposure were 3.0 (Cl = 1.5-5.7) among men and 6.2 (CI=2.0-19.7) among women. An elevated risk of squamous cell carcinoma was observed among men (OR=2.5, CI=0.6-10.1) and women (OR = 3.5, CI = 1.2-10.5) with a high probability of exposure to formaldehyde. Exposure to textile dust was associated with non-significantly elevated risk of adenocarcinoma, among women only: the OR for the high level of cumulative exposure was 2.5 (CI = 0.7-9.0). High level of asbestos exposure was associated with a significantly increased risk of squamous cell carcinoma among men (OR = 1.6, CI = 1.1-2.3).

CONCLUSIONS

The results of this pooled analysis support the hypothesis that occupational exposure to formaldehyde increases the risk of sinonasal cancer, particularly of adenocarcinoma. They also indicate an elevated risk of adenocarcinoma among women exposed to textile dust, and suggest that exposure to asbestos may increase the risk of squamous cell carcinoma.

Study of ethmoidal mucosa in a population at occupational high risk of sinonasal adenocarcinoma

The occurrence of nasal adenocarcinomas was first described in 1965. Since 1988 these tumors have been accepted as an occupational disease for woodworkers in Italy. There are several underlying reasons why there is interest in studying the ways in which sinonasal adenocarcinomas occur. Often diagnosed at advanced stages of development because their symptoms are non-specific, these tumors are associated with a high mortality rate. A multidisciplinary study protocol was developed in this investigation. The aim was to identify the factors and conditions that promote sinonasal tumor growth in a population at risk due to occupational exposure to wood dust. Sixty-eight carpenters with a minimum of 10 years exposure to wood dust were studied. The control group comprised 81 volunteers. The patients underwent the following protocol: completion of a case report form, physical examination, evaluation of nasal cavity patency, clinical laboratory tests and histological study of the nasal mucosa. Our study provides significant evidence of the elevated incidence of pavimentous metaplasia in workers occupationally exposed to wood dust. In addition, it underscores a significant deficit of immunoglobulin A in such workers compared to the controls. However, we did not find, as reported elsewhere in the literature, a statistically significant difference between cases and controls as regards nasal symptoms and hyperemia of the nasal mucosa. Our study showed that, even in the absence of evident sinonasal lesions, it is still possible to determine an increased incidence of morphofunctional changes in subjects occupationally exposed to wood dust. Our findings may lead to the identification of occupational groups prone to elevated risk of the disease.

[Nasal-paranasal sinus polyposis]

1.

POLYPOSIS AND ALLERGY

Nasosinusal polyposis and allergy must be considered as two distinct conditions. 2.

POLYPOSIS

Approximately 1% of the general population has nasosinusal polyposis, a condition strongly associated with asthma (about one-third of the patients with polyposis have asthma). Patients with nasosinusal should undergo a complete respiratory examination in order to search for asthma or an asthma equivalent. 3.

EOSINOPHILS

Eosiophils play a crucial role in the inflammatory reaction, releasing almost all the known inflammatory mediators: cytokines, chemokines and growth factors. 4.

EPITHELIAL CELL

The epithelial cell probably plays a very important role. 5.

MEDICAL TREATMENT

Long-duration intranasal corticotherapy is the basis of drug treatment. Short courses of oral corticosteroids may be useful during acute episodes in inflammation. The exact effect of oral corticosterid is not clearly elucidated but it is known that non-steroidal antiinflammatory drugs (NSAID) are contraindicated in polyposis. 6.

SURGICAL TREATMENT

Surgery is reserved for medical failures or for patients with a contraindication for drug therapy. Endonasal ethmoidectomy is the basis treatment. 7.

PERSPECTIVES

Better understanding of the underlying pathophysiology and the probable genetic component will determine future treatments. Perspectives include antiinflammatory drugs currently reserved for other conditions (antileucotriene, antiTNFa, IL-18) and elaboration of new antiinflammatory drugs.

Nasopharyngeal extension of a craniopharyngioma in a 4 year old girl

Nasopharyngeal extension of a craniopharyngioma is very rare and usually presents with headache, nasal obstruction and visual disturbances. We present a case of a 4 year old girl, who became symptomatic with visual deterioration. MRI showed a huge supra - and infrasellar cystic craniopharyngioma with extension into the sphenoid sinus. Primary treatment was a transnasal puncture of the cyst followed by a subfrontal approach with removal of the tumour preserving the chiasm and optic nerves. The visual acuity postoperatively improved while she needed hormone replacement due to panhypopituitarism. Follow-up 12 months after the operation showed no recurrence. This is the youngest patient of about 27 patients reported so far in the literature.

[Treatment of sino-nasal polyposis by Candida albicans immunotherapy: apropos of 4 cases]

The NSP is an inflammatory chronic disease of the mucous of nose and sinuses. None etiological treatment is known up to now. The aim of this study is to consider a model of autoallergy as etiology for NSP proven by specific immunotherapy (STI) to Candida albicans (CA).

METHODS

Four NSP treated by SIT to Candida albicans are reported. The patients are treated either by subcutaneous injections or sublingual drops. The frequency is one injection per week or a few drops per day (absorbed extract on calcium phosphate or aqueous Stallergenes).

RESULTS

The cumulated doses varies from 465 Index of Concentration (IC) to 117500 IC on a period of 3 to 4 years. The results are evaluated according the rhino-sinusal semeiology, the intensity of symptoms, and the stage of polyposis. The SIT is also active on both a late and an immediate components for the symptoms, and the cutaneous tests. The results are significant 60% to 80% of improvement. The viral or bacterial infections reactivate both types of hypersensitivity and they are prevented by SIT. The nasal hyperactivity observed as a more advanced non specific stage of the PNS is also improved by ITS. In two of the clinical cases, the pollenogenic seasonal obstruction is added to the nasal perennial obstruction in a sharp manner. The pollenogenic allergy is also improved after SIT to CA without any other associated SIT.

CONCLUSION

The model of autoallergy already proven as etiology for atopic dermatitis can serve as a base of exploration of PNS. That is showing the presence of IgE antibody corresponding to intracellular proteinic autoallergens having an analogy to environment allergens. The allergy to Candida albicans can thus be considered as an etiology of the PNS.

[Ethmoid adenocarcinomas: retrospective study of 76 patients]

From the retrospective study of 76 adenocarcinomas of the ethmoid sinuses, results were expressed in two terms: the morbidity related to surgery and the oncologic outcome. This case study extends between 1975 and 2000. It includes 71 men and 5 women, with an average of 61 years. 81% of them works in wood dust, with a mean duration of exposure of 26 years. The diagnosis of adenocarcinoma is realized in the three months after the first signs, essentially rhinologicals, next neurologicals and ophthalmologicals. The majority of tumors were classified as T3N0M0, i.e. 57.89%. The treatment of this tumors is surgical: 34.2% surgical only and 59.2% with radiotherapy. The transfacial approach (paralateronasal and degloving) and the combined surgery are respectively performed in 36 patients and 35 patients. 23.2% patients had a local recurrence, and 10% developed cervical nodes and systemic metastasis. Survival rate based on the Kaplan-Meier actuarial method is 82% at 3 years, 80% at 5 years, 72% at 10 years. The prognosis of ethmoidal cancer is strictly correlated to local control. Local recurrence is statistically more likely in patients with involvement of the dura, brain and sphenoid sinus. With the analysis of the carcinologics results, we discuss the therapeutics indications of the adenocarcinomas and a new classification. Taking in account the involvement of the dura, sphenoid and orbit. We did not find any statistical differences between T3 patients treated by combined approach (n = 13) or by transfacial approach (n = 15).

Sinonasal radiation-associated osteosarcoma after combined therapy for rhabdomyosarcoma of the nose

Radiation-associated (RA) osteosarcomas (OS) are exceptional in children, presenting more frequently in middle-aged and elderly patients. This is a case report of RA-OS of the sinonasal cavities in a 13-yr-old girl after combined therapy for rhabdomyosarcoma (RMS) of the nose diagnosed at the age of five. The treatment of choice is radical surgery with wide margins and postoperative adjuvant chemotherapy and radiotherapy. Despite an episode of recurrence, at the present time the patient is alive and free of disease 5 yr after the initial treatment of OS. The association between radiation, chemotherapy and sarcomas is reviewed and discussed.

Malignant tumors of the nose and paranasal sinuses: a retrospective review of 291 cases

Malignant neoplasms of the nose and paranasal sinuses are not common among the general population. We present a retrospective study of 291 cases of malignant tumors of the nose and paranasal sinuses that were diagnosed in a northern Romanian population over a period of 35 years. We review the etiology, diagnosis, prognosis, and treatment of these tumors.

Factors in the pathogenesis of tumors of the sphenoid and maxillary sinuses: a comparative study

OBJECTIVES/HYPOTHESIS

To explain the processes that lead to the development of tumors in the maxillary and sphenoid sinuses.

STUDY DESIGN

A 32-year review of the world's literature on neoplasms of these two sinuses and a randomized case-controlled study comparing the normal mucosal architecture of the maxillary to the sphenoid sinus.

METHODS

Analysis of a 32-year world literature review reporting series of cases of maxillary and sphenoid sinus tumors. Tumors were classified by histological type and separated into subgroups if an individual incidence rate was reported. Histomorphometry of normal maxillary and sphenoid sinus mucosa was performed in 14 randomly selected patients (10 sphenoid and 4 maxillary specimens). Specimens were fixed in 10% formalin, embedded in paraffin, and stained with periodic acid-Schiff (PAS) and hematoxylin. Histomorphometric analysis was performed with a Zeiss Axioscope light microscope (Carl Zeiss Inc., Thornwood, NY) mounted with a Hamamatsu (Hamamatsu Photonics, Tokyo, Japan) color-chilled 3 charge coupled device digital camera. The images were captured on a 17-inch Sony (Sony Corp., Tokyo, Japan) multiscan monitor and analyzed with a Samba 4000 Image Analysis Program (Samba Corp., Los Angeles, CA). Five random areas were selected from strips of epithelium removed from each sinus, and goblet and basal cell measurements were made at magnifications x 100 and x 400.

RESULTS

The literature review revealed that the number and variety of tumors in the maxillary sinus are much greater than those in the sphenoid. The incidence of metastatic lesions to each sinus is approximately equal. No recognized pattern of spread from any particular organ system could be determined. On histomorphometric study there were no statistically significant differences between the sinuses in the concentration of goblet cells, basal cells, or seromucinous glands.

CONCLUSIONS

Factors involved in the pathogenesis of tumors of the maxillary and sphenoid sinuses include differences in nasal physiology, embryology, morphology, and topography. There are no significant histological differences in the epithelium and submucous glands between the two sinuses to explain the dissimilar formation of neoplasms.

Tumors of the nasal cavity and the paranasal sinuses: an update of current opinions and advances in etiology, diagnostic and therapy

Sinonasal malignant tumors account for a very small portion of the huge clinical spectrum in otolaryngology. There is an enormous histological diversity of tumors arising in the sinonasal system, demanding different therapeutic approaches. Sinonasal tumors, often diagnosed only in advanced stages, can be extremely disfiguring and the head neck surgeon has to deal besides cure and survival with quality of life aspects of his patient. It is impossible to cover all relevant aspects for the treatment of sinonasal neoplasias in a single presentation. This overview treats with epidemiology, etiology, molecular biological findings, diagnosis and new therapeutic concepts. Personal experiences will be presented along with advances in research and treatment of the last decade.

An analysis of bone and head sinus cancers in radium dial painters using a two-mutation carcinogenesis model

Bone and head sinus cancer incidence after ingestion of 226Ra and 228Ra by radium dial painters is analysed using a two-mutation clonal expansion model for radiation carcinogenesis, taking into account the retention and radiation patterns of these nuclides in the body. The best fit is obtained for compact bone retention and efficient diffusion of 222Rn to the bone cavities and radiation action on both mutation rates of the cancer model, as found in a similar analysis of bone sarcomas after 226Ra injection in beagles. The model parameters of the best fit are consistent with cellular radiobiological data and a previous analysis of lung cancer in uranium miners. Due to the low background incidence of bone and head sinus cancer, the resulting dose-effect relationships for these cancers are linear-quadratic with radium ingestion and alpha radiation dose. These results do not support a threshold dose concept, but the risks at low doses calculated by the model come out to about a factor 10 lower than using a linear extrapolation of the data to low doses, a procedure currently applied by ICRP and EPA. Furthermore, the model results indicate radiation risks at low doses to be related with background cancer incidence between relative and absolute radiation risk projections. The results, which are dependent on the model assumptions, might be more generally applicable for bone seekers and will therefore need further study to arrive at better radiation risk estimations.

Malignant neoplasms of the nasal cavity and paranasal sinuses: a series of 256 patients in Mexico City and Monterrey. Is air pollution the missing link?

Air pollution is a serious health problem in major cities in Mexico. The concentrations of monitored criteria pollutants have been above the US National Ambient Air Quality Standards for the last decade. To determine whether the number of primary malignant nasal and paranasal neoplasms has increased, we surveyed 256 such cases admitted to a major adult oncology hospital located in metropolitan Mexico City (MMC) for the period from 1976-1997 and to a tertiary hospital in Monterrey, an industrial city, for the period from 1993-1998. The clinical histories and histopathologic material were reviewed, and a brief clinical summary was written for each case. In the MMC hospital the number of newly diagnosed nasal and paranasal neoplasms per year for the period from 1976-1986 averaged 5.1, whereas for the next 11 years it increased to 12.5. The maximal increase was observed in 1995-1997, with an average of 20.3 new cases per year (P = 0.0006). The predominant neoplasms in these series were non-Hodgkin's lymphoma, squamous cell carcinoma, melanoma, adenocarcinoma, Schneiderian carcinoma, and nasopharyngeal carcinoma. In the Monterrey hospital a 2-fold increase in the numbers of newly diagnosed nasal and paranasal neoplasms was recorded between 1993 and 1998. The predominant MMC neoplasm in this series, namely nasal T-cell/natural killer cell non-Hodgkin's lymphoma, is potentially Epstein-Barr virus related. Nasal and paranasal malignant neoplasms are generally rare. Environmental causative factors include exposure in industries such as nickel refining, leather, and wood furniture manufacturing. Although epidemiologic studies have not addressed the relationship between outdoor air pollution and sinonasal malignant neoplasms, there is strong evidence for the nasal and paranasal carcinogenic effect of occupational aerosol complex chemical mixtures. General practitioners and ear, nose, and throat physicians working in highly polluted cities should be aware of the clinical presentations of these patients. Identification of this apparent increase in sinonasal malignant neoplasms in two urban Mexican polluted cities warrants further mechanistic and epidemiologic studies.