Cigarette smoking and nasopharyngeal carcinoma

The association between chronic sinonasal inflammation and nasopharyngeal carcinoma - A systematic review and meta-analysis

PURPOSE

There has been mounting evidence that inflammation is a key risk factor towards the development of certain cancers. Past studies have shown associations between nasopharyngeal carcinoma (NPC) and sinonasal tract inflammation. We aim to conduct a review and meta-analysis on the association between NPC and chronic sinus inflammation.

MATERIALS AND METHODS

We conducted a meta-analysis, searching 4 international databases from 1 January 1973 to 28 March 2022 for studies reporting on sinonasal inflammation and NPC in adult patients (>18 years old). We included cohort, case-control or cross-sectional studies. These studies must examine the association between a prior history of sinonasal inflammation and the risk of developing NPC. The outcome is the incidence of NPC in patients who had prior sinonasal inflammation.

RESULTS

8 studies (8245 NPC; 1,036,087 non-NPC) were included. The overall odds ratio (OR) of patients having NPC after reporting sinonasal inflammation was 1.81 (95 % CI 1.73-1.89). Of note, chronic rhinosinusitis (CRS) (OR of 1.78 (95 %-CI: 1.68-1.90)) was more closely associated with an increased risk of NPC, as compared to allergic rhinitis (AR) (OR of 1.60 (95 %-CI: 1.52-1.68)).

CONCLUSION

Chronic sinonasal inflammation is significantly associated with NPC in this systemic review and meta-analysis. The true cause-effect relationship and the potential effects of targeted screening need to be explored thoroughly with large scale prospective studies.

Smoking and nasopharyngeal cancer: individual data meta-analysis of six prospective studies on 334 935 men

BACKGROUND

The role of smoking in nasopharyngeal carcinoma (NPC) remains uncertain, especially in endemic regions. We conducted an individual participant data (IPD) meta-analysis of prospective cohort studies to investigate the associations between smoking exposure and risk of NPC.

METHODS

We obtained individual participant data of 334 935 male participants from six eligible population-based cohorts in NPC-endemic regions, including two each in Guangzhou and Taiwan, and one each in Hong Kong and Singapore. We used one- and two-stage approaches IPD meta-analysis and Cox proportional hazard models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of NPC for smoking exposure adjusting for age and drinking status.

RESULTS

During 2 961 315 person-years of follow-up, 399 NPC evens were ascertained. Risks of NPC were higher in ever versus never smokers (HRone-stage = 1.32, 95% CI = 1.07-1.63, P = 0.0088; HRtwo-stage = 1.27, 1.01-1.60, 0.04). These positive associations appeared to be stronger in ever smokers who consumed 16+ cigarettes/day (HRone-stage = 1.67, 95% CI = 1.29-2.16, P = 0.0001), and in those who started smoking at age younger than 16 (2.16, 1.33-3.50, 0.0103), with dose-response relationships (P-values for trend = 0.0028 and 0.0103, respectively). Quitting (versus daily smoking) showed a small reduced risk (stopped for 5+ years: HRone-stage = 0.91, 95% CI = 0.60-1.39, P = 0.66; for former smokers: HRtwo-stage = 0.84, 0.61-1.14, 0.26).

CONCLUSIONS

This first IPD meta-analysis from six prospective cohorts in endemic regions has provided robust observational evidence that smoking increased NPC risk in men. NPC should be added to the 12-16 cancer sites known to be tobacco-related cancers. Strong tobacco control policies, preventing young individuals from smoking, would reduce NPC risk in endemic regions.

Intake of Alcohol and Tea and Risk of Nasopharyngeal Carcinoma: A Population-Based Case-Control Study in Southern China

BACKGROUND

The potential effect of alcohol or tea intake on the risk of nasopharyngeal carcinoma (NPC) remains controversial.

METHODS

In a population-based case-control study in southern China, we assessed alcohol or tea intake from 2,441 histopathologically confirmed NPC cases and 2,546 controls. We calculated mean daily ethanol (g/day) and tea intake (mL/day). Fully adjusted ORs with 95% confidence intervals (CI) were estimated using logistic regression; potential dose-response trends were evaluated using restricted cubic spline analysis.

RESULTS

Compared with nondrinkers, no significantly increased NPC risk in men was observed among current alcohol drinkers overall (OR, 1.08; 95% CI, 0.93-1.25), nor among current heavy drinkers (OR for ≥90 g/day ethanol vs. none, 1.32; 95% CI, 0.95-1.84) or former alcohol drinkers. Current tea drinking was associated with a decreased NPC risk (OR, 0.73; 95% CI, 0.64-0.84). Compared with never drinkers, those with the low first three quintiles of mean daily current intake of tea were at significantly lower NPC risk (OR, 0.53, 0.68, and 0.65, respectively), but not significant for the next two quintiles. Current daily tea intake had a significant nonlinear dose-response relation with NPC risk.

CONCLUSIONS

Our study suggests no significant association between alcohol and NPC risk. Tea drinking may moderately reduce NPC risk, but the lack of a monotonic dose-response association complicates causal inference.

IMPACT

Tea drinking might be a healthy habit for preventing NPC. More studies on biological mechanisms that may link tea with NPC risk are needed.

Subtype Specific Nasopharyngeal Carcinoma Incidence and Survival Trends: Differences between Endemic and Non-Endemic Populations

BACKGROUND

While nasopharyngeal carcinoma (NPC) is rare in non-endemic regions such as the North America, endemic countries, such as Thailand, continue to struggle with high incidence and mortality rates. NPC has a complex etiology that varies by histological subtype.

METHODS

NPC cases (1990-2014) were identified using the International Classification of Diseases for Oncology (ICD-O) code C11 from the Chiang Mai, Khon Kaen, Lampang, and Songkhla cancer registries and compared to Asian/Pacific Islanders (A/PI) from the US SEER program. Age-standardized incidence rates and changes in annual percent change (APC) for overall and subtype specific NPC were assessed using R and Joinpoint. Kaplan Meier curves were generated in SAS to evaluate differences in survival by sex, year of diagnosis and histological subtype. Five-year relative survival estimates were calculated between 2000-2014.

RESULTS

Non-keratinizing NPC predominated across all registries except Songkhla, where the keretinizing subtype made up ~60% of all reported cases. Incidence of keratinizing NPC significantly decreased among Chiang Mai males between 1996 and 2014 (APC:-13.0 [95%CI:-16.2, -9.6]), Songkhla females (APC:-4.0 [95%CI: -7.4, -0.5]) and males between 2006 and 2014 (APC:-15.5 [95%CI:-25.0, -4.7]), as well as A/PI females (APC:-5.1 [95%CI:-6,7, -3.4]) and males (APC: -4.8 [95%CI:-5.9, -3.7]). Non-keratinizing NPC increased among Songkhla males (APC:4.3 [95%CI:1.8, 6.9]). The keratinizing subtype exhibited the worst survival, while the non-keratinizing undifferentiated subtype had the best survival. Although US A/PI had the highest 5-year relative survival estimates, among the Thai registries Chiang Mai had the best and Lampang the worst survival.

CONCLUSION

Although US A/PIs exhibited similar rates of NPC as seen in the endemic Thai population, improved tobacco control has led to a decrease in keratinizing NPC incidence irrespective of geography. Additionally, while challenges associate with access to care may still exist among rural Thais, chemoradiation was shown to confer a survival benefit in non-keratinizing NPC treatment.

Association Between Alcohol Consumption and Risk of Nasopharyngeal Carcinoma: A Comprehensive Meta-Analysis of Epidemiological Studies

BACKGROUND

Alcohol consumption is increasing all over the world, but whether it is an independent factor affecting the occurrence of nasopharyngeal carcinoma (NPC) is inconsistent in many studies. We aimed to explore the association between alcohol consumption and NPC risk by integrating existing evidence in a meta-analysis.

METHODS

We searched for relevant articles published up to August 2018 in PubMed, Cochrane Library, Web of Science, and China National Knowledge infrastructure (CNKI). The Newcastle-Ottawa scale was used to assess the quality of the included studies. Odds ratios (ORs) or relative risks were pooled to estimate the associations between alcohol consumption and NPC risk.

RESULTS

The meta-analysis of cohort studies showed no significant association between alcohol consumption and NPC, but pooled results from case-control studies indicated that ever drinking increased the probability of NPC versus nondrinking (OR = 1.10; 95% confidence interval [CI]: 1.01, 1.19). As compared with nondrinkers, high-frequency drinking (≥7 times/wk) increased the NPC probability (OR = 1.29; 95% CI: 1.05, 1.53) and low-frequency drinking (<7 times/wk) decreased the probability (OR = 0.77; 95% CI: 0.60, 0.94), as did shorter duration of drinking (<20 years) (OR = 0.64; 95% CI: 0.49, 0.79). On subgroup analyses, significant pooled results were observed for studies with high quality, with hospital-based controls and with adjustment for confounding factors, smoking, age, and sex.

CONCLUSIONS

The risk of NPC may increase with alcohol consumption. Ever drinking increased the risk versus nondrinking. Additionally, high-frequency drinking increased the risk, but low-frequency drinking decreased it to some extent. Further intensive studies based on well-designed methods are needed to examine the association.

Cigarette smoking and the risk of nasopharyngeal carcinoma: a meta-analysis of epidemiological studies

OBJECTIVE

The role of cigarette smoking as an independent risk factor for patients with nasopharyngeal carcinoma (NPC) is controversial. We attempted to provide evidence of a reliable association between cigarette smoking and the risk of NPC.

DESIGN

Meta-analysis.

DATA SOURCES

PubMed online and the Cochrane Library of relevant studies published up to February 2016.

ELIGIBILITY CRITERIA

All studies had to evaluate the relationship between NPC and cigarette smoking with never smokers as the reference group.

OUTCOMES

The primary outcome was the adjusted OR, RR or HR of NPC patients comparing smoking with never-smoking; the second was the crude OR, RR or HR.

RESULTS

We identified 17 case-control studies and 4 cohort studies including 5960 NPC cases and 429 464 subjects. Compared with never smokers, current smokers and ever smokers had a 59% and a 56% greater risk of NPC, respectively. A dose-response relationship was identified in that the risk estimate rose by 15% (p<0.001) with every additional 10 pack-years of smoking, and risk increased with intensity of cigarette smoking (>30 cigarettes per day). Significantly increased risk was only found among male smokers (OR, 1.36; 95% CI 1.15 to 1.60), not among female smokers (OR, 1.58; 95% CI 0.99 to 2.53). Significantly increased risk also existed in the differentiated (OR, 2.34; 95% CI 1.77 to 3.09) and the undifferentiated type of NPC (OR, 1.15; 95% CI 0.90 to 1.46). Moreover, people who started smoking at younger age (<18 years) had a greater risk than those starting later for developing NPC (OR, 1.78; 95% CI 1.41 to 2.25).

CONCLUSIONS

Cigarette smoking was associated with increased risk of NPC, especially for young smokers. However, we did not find statistical significant risks of NPC in women and in undifferentiated type, which might warrant further researches.

Associations of lifestyle and diet with the risk of nasopharyngeal carcinoma in Singapore: a case-control study

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a commonly diagnosed cancer in Southeast Asia. Many studies have examined the risk factors for NPC, yet the roles of some risk factors remain inconclusive. The purpose of this study was to examine associations between modifiable lifestyle factors and the risk of NPC in the Singaporean population.

METHODS

We conducted a case-control study in Singapore with 300 patients and 310 controls who were recruited between 2008 and 2012. Each control was selected and individually matched to each patient based on sex, ethnicity, and age (±5 years). A total of 290 pairs of cases and controls were matched successfully. We examined lifestyle factors such as tobacco smoking, alcohol drinking, various salted and preserved food consumption, and weaning practices.

RESULTS

After adjusting for covariates, multivariate analysis showed that those participants who were current smokers and had ever smoked tobacco had a higher risk of NPC than participants who had never smoked, with odds ratios (ORs) of 4.50 (95% confidence interval [CI] 2.58-7.86; P < 0.001) and 2.52 (95% CI 1.54-4.12; P < 0.001), respectively. Those who consumed salted vegetables at least once a week also showed a significantly increased risk of NPC than those who never or rarely consumed salted vegetables, with an OR of 4.18 (95% CI 1.69-10.38; P = 0.002).

CONCLUSION

Smoking (currently and ever-smoked) and consuming salted vegetables once a week or more were lifestyle risk factors for NPC, and changes of these factors for the better may reduce the risk of NPC.

Quantitative association of tobacco smoking with the risk of nasopharyngeal carcinoma: a comprehensive meta-analysis of studies conducted between 1979 and 2011

Over the years, many studies have attempted to establish a link between tobacco smoking and an increased risk of nasopharyngeal carcinoma (NPC), but their results have been inconsistent. To clarify this link, we first conducted a comprehensive meta-analysis to integrate the findings of epidemiologic studies from the last half-century. The methodology used for this study followed the checklist proposed by the Meta-analysis of Observational Studies in Epidemiology (MOOSE) Group. Pooled risk estimates were generated using a random-effects model. Twenty-eight case-control studies and 4 cohort studies involving a total of 10,274 NPC cases and 415,266 comparison subjects were included. A substantial effect of smoking on the risk of NPC was identified in this study. The results showed that ever smokers had a 60% greater risk of developing the disease than never smokers (95% confidence interval: 1.38, 1.87); this was a robust dose-dependent association. More importantly, stronger associations were observed in low-risk populations and among persons with the predominant histological type of differentiated NPC than in high-risk populations and persons with an undifferentiated type; the odds ratios were 1.76 and 2.20, respectively, versus 1.29 and 1.27. In this comprehensive meta-analysis, well-established statistical evidence was provided about the role of tobacco smoking in the etiology of NPC.

Non-viral environmental risk factors for nasopharyngeal carcinoma: a systematic review

This review aims to systematically summarize the epidemiological studies on nasopharyngeal carcinoma (NPC) conducted over the past half century, covering descriptive epidemiological studies and reports on non-viral risk factors. Multiple lines of epidemiologic evidence for established risk factors are systematically presented in comprehensive tables. The potential interactions among environmental factors and genetic components, and also the impacts of parallel sequencing technology on the aetiology of NPC are discussed. Finally, we propose a modified model for the pathogenesis of nasopharyngeal carcinoma based on the current knowledge.

Tobacco smoking, alcohol drinking, and the risk of different histological types of nasopharyngeal cancer in a low-risk population

Nasopharyngeal carcinoma (NPC) is rare in western Countries. Tobacco smoking is a well-recognised risk factor, whereas the role of alcohol drinking is still in debate. We conducted a hospital-based case-control study in Italy on 150, histologically-confirmed, NPC cases of Caucasian ethnicity, aged 18-76years, including 118 undifferentiated NPCs and 22 differentiated squamous-cell NPC. Controls were 450 Caucasian cancer-free patients admitted to general hospitals for acute conditions. Cases and controls were matched according to sex, age, and place of residence. Logistic regression was used to estimate odds ratios (OR) and the corresponding 95% confidence intervals (CI) while adjusting for known confounders. No significant association emerged between tobacco smoking and all NPCs (OR for current vs. never smokers=1.52; 95% CI: 0.89-2.60). Conversely, for differentiated NPC only, statistically significant elevated OR were associated with increasing smoking intensity (OR for ⩾15cigarettes/day=5.40; 95% CI: 1.34-21.76) and duration of the habit (OR for ⩾32years=4.48; 95% CI: 1.11-18.04). Although alcohol drinking was not, per se, significantly associated to NPC risk, the combination of tobacco smoking and alcohol drinking accounted for 57% of differentiated NPCs, whereas it accounted for only 14% of undifferentiated carcinomas. Our findings suggest that, in western populations, NPC includes two separate entities: the differentiated NPC, associated with tobacco smoking like other cancers of head and neck, and the undifferentiated NPC, upon which tobacco smoking has little or no influence.

Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa

Background:

The lifestyle risk factors for nasopharyngeal carcinoma (NPC) in North Africa are not known.

Methods:

From 2002 to 2005, we interviewed 636 patients and 615 controls from Algeria, Morocco and Tunisia, frequency-matched by centre, age, sex, and childhood household type (urban/rural). Conditional logistic regression was used to evaluate the association of lifestyles with NPC risk, controlling for socioeconomic status and dietary risk factors.

Results:

Cigarette smoking and snuff (tobacco powder with additives) intake were significantly associated with differentiated NPC but not with undifferentiated carcinoma (UCNT), which is the major histological type of NPC in these populations. As demonstrated by a stratified permutation test and by conditional logistic regression, marijuana smoking significantly elevated NPC risk independently of cigarette smoking, suggesting dissimilar carcinogenic mechanisms between cannabis and tobacco. Domestic cooking fumes intake by using kanoun (compact charcoal oven) during childhood increased NPC risk, whereas exposure during adulthood had less effect. Neither alcohol nor shisha (water pipe) was associated with risk.

Conclusion:

Tobacco, cannabis and domestic cooking fumes intake are risk factors for NPC in western North Africa.

Alcohol consumption and the risk of nasopharyngeal carcinoma: a systematic review

The evidence concerning the influence of alcohol drinking on the risk of nasopharyngeal carcinoma (NPC) has yielded intriguing findings but has lacked a clear-cut interpretation due to inconsistencies. To unify this body of evidence, we performed a systematic review. With funding and using a protocol developed by the World Cancer Research Fund (WCRF), 15 bibliographic databases were searched for epidemiological studies that reported a measure of association between alcoholic beverage consumption and NPC. Pooled odds ratios (ORs) for highest-vs.-lowest categories of total alcohol intake was obtained by using an inverse-variance weighted random-effects model. A dose-response trend was examined in models using generalized least square estimation. The search identified 14 case-control studies from 5 countries. For total alcohol intake, the pooled ORs in a comparison of the highest to the lowest category was 1.33 (95% CI: = 1.09-1.62) in 11 studies. Data from 6 studies indicated a J-shape dose-response trend, with NPC risk decreasing with up to 15 drinks/wk and increasing with higher intake. Fewer data were available to assess the associations between NPC and intake of beer, wine, and spirits. The potential J-shaped dose-response trend suggests a reduced risk of NPC related to the light alcohol drinking, an observation that warrants further study. Considered in total, the quantitative summaries of the case-control evidence suggest that heavy alcohol consumption is associated with an increased risk of NPC.

The enigmatic epidemiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology that is not completely understood. Although NPC is rare in most populations, it is a leading form of cancer in a few well-defined populations, including natives of southern China, Southeast Asia, the Arctic, and the Middle East/North Africa. The distinctive racial/ethnic and geographic distribution of NPC worldwide suggests that both environmental factors and genetic traits contribute to its development. This review aims to summarize the current knowledge regarding the epidemiology of NPC and to propose new avenues of research that could help illuminate the causes and ultimately the prevention of this remarkable disease. Well-established risk factors for NPC include elevated antibody titers against the Epstein-Barr virus, consumption of salt-preserved fish, a family history of NPC, and certain human leukocyte antigen class I genotypes. Consumption of other preserved foods, tobacco smoking, and a history of chronic respiratory tract conditions may be associated with elevated NPC risk, whereas consumption of fresh fruits and vegetables and other human leukocyte antigen genotypes may be associated with decreased risk. Evidence for a causal role of various inhalants, herbal medicines, and occupational exposures is inconsistent. Other than dietary modification, no concrete preventive measures for NPC exist. Given the unresolved gaps in understanding of NPC, there is a clear need for large-scale, population-based molecular epidemiologic studies to elucidate how environmental, viral, and genetic factors interact in both the development and the prevention of this disease.

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 chlorophenol and the risk of nasal and nasopharyngeal cancers among U.S. men aged 30 to 60

BACKGROUND

Elevated rates of nasal and nasopharyngeal cancers have been associated with wood-related occupational exposures, including chlorophenols, formaldehyde, and wood dust.

METHODS

Occupational information was obtained from 43 nasal carcinoma cases, 92 nasopharyngeal carcinoma cases, and 1909 controls, by interview. Exact conditional logistic regression was used to evaluate the association of these cancers with chlorophenol exposure, estimated from a review of verbatim responses.

RESULTS

Both nasal and nasopharyngeal cancers were significantly associated with estimated duration of chlorophenol exposure. For nasopharyngeal cancer, elevated risk was observed among those who held jobs assigned medium or high intensity chlorophenol exposure (n(exposed)=18, OR=1.94, 95% CI=1.03-3.50) and among those with 10+ years in jobs assigned high intensity with high certainty (n(exposed)=3, OR=9.07, 95% CI=1.41-42. 9). Controlling for estimated formaldehyde and wood dust exposure did not alter these findings, as much of the estimated chlorophenol exposure was among machinists.

CONCLUSIONS

These findings support the hypothesis that occupational exposure to chlorophenol is a risk factor for nasal and nasopharyngeal cancer, although the role of machining-related exposures warrants further assessment.

Aldehyde dehydrogenase 2 and glutathione S-transferase M 1 polymorphisms in relation to the risk for oral cancer in Japanese drinkers

We investigated 191 patients with oral cancer (121 males and 70 females) and 121 non oral cancer patients (69 males and 52 females), both groups with a history of alcohol use. Blood was analyzed with aldehyde dehydrogenase 2 (ALDH 2) and glutathione S-transferase M 1 (GSTM 1) genotyping. ALDH 2 genotyping was performed by polymerase chain reaction (PCR)-Restriction fragment length polymorphism (RFLP) method and GSTM 1 genotyping was amplified with PCR using GSTM 1 specific primers. In the oral cancer group, the alcohol-drinking rate (59.7%) was significantly higher than in the non cancer group (alcohol-drinking rate 27.3%, p < 0.01). The incidence of inactive ALDH 2 and GSTM 1 in the cancer group with an alcohol-drinking habit was 34.2 and 67.5% and was higher than in the non cancer group with an alcohol-drinking habit (15.1, 45.5%).

Increased incidence of tongue cancer after primary radiotherapy for nasopharyngeal carcinoma--the possibility of radiation carcinogenesis

The aim of this study was to define the risk of tongue and other aerodigestive tract cancers developing after primary radiation therapy for nasopharyngeal carcinoma (NPC). A cohort of 903 patients with non-disseminated NPC given radical radiotherapy between 1984 and 1989 was studied for the incidence of tongue cancer and other malignancies during follow-up. A contemporary cohort of 87 patients with tongue cancer, without a history of NPC, was studied for demographic data, cigarette smoking and alcohol consumption habits. These were then compared with all the NPC patients and with the NPC patients who later developed tongue cancers. There was a significantly increased number of tongue cancers following radiotherapy for NPC. The risk of developing tongue cancer after radiotherapy for NPC was 0.13% per patient per year. There was no increase in the number of other malignancies. The association between NPC and tongue cancer was that of a non-random temporal sequence with tongue cancers following NPC but not in the reverse order. The demographic data and smoking and alcohol consumption history of the 7 NPC patients who subsequently developed tongue cancer were significantly different from the de novo tongue cancer patient population. The absence of common aetiological factors between NPC and tongue cancer and the non-random sequence of tongue cancers occurring after NPC suggests that these seven tongue cancers could be radiation induced. The estimated radiation dose received by the part of the tongue developing cancer was substantial and significantly higher than the dose to the cancer-free tongue. An increase of tongue cancers after radiotherapy for NPC is reported and arguments are made in support of the hypothesis that these were radiation-induced malignancies. We suggest a decrease in the volume of tongue included within the planning target volume of NPC in the absence of oropharyngeal and/or parapharyngeal infiltration. Awareness of the association should make early diagnosis of this likely radiation-induced cancer possible.

Pretreatment assessment and dental management of patients with nasopharyngeal carcinoma

Patients who present with nasopharyngeal carcinoma (NPC) require through oral and dental assessment prior to treatment of the malignancy. We assessed the oral status of 57 consecutive patients with a diagnosis of NPC. In this study, identified risk factors for NPC were seen to be different in Asian versus non-Asian patients. Epstein-Barr virus seropositivity was seen in all Asian patients and in 69% of non-Asian patients (P = 0.00006), and reported alcohol use was greater in the non-Asian patients. In this study it was found that 68% of dentate patients required dental extractions primarily due to periodontal disease. Even in patients who reported receiving regular dental care (28%) extractions prior to radiation therapy were suggested. Oral complications of radiation therapy were reported by 84% of patients, with the most common being xerostomia. Clinical diagnosis of candidiasis (16%), rampant caries (10% of dentate patients) and difficulties with dentures (25% of denture wearers) were noted. In addition to pretreatment assessment, continuing oral and dental management is needed for patients with NPC.

CYP2E1 genetic polymorphisms and risk of nasopharyngeal carcinoma in Taiwan

BACKGROUND

Nasopharyngeal carcinoma occurs disproportionately among individuals of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is known to activate nitrosamines and other carcinogens that are possibly involved in the development of this disease. Certain alleles of the CYP2E1 gene are thought to be more highly expressed than others, and their distribution varies between Asian and Caucasian populations. We conducted a case-control study to investigate whether such variations affect the risk of developing nasopharyngeal cancer.

METHODS

Three hundred sixty-four patients with nasopharyngeal carcinoma (96% of 378 eligible patients) and 320 control subjects (86% of 374 eligible subjects) were studied. A risk factor questionnaire was administered to participants to assess factors postulated to be linked to nasopharyngeal carcinoma. Peripheral blood was obtained from all subjects and DNA was purified from nucleated cells. A polymerase chain reaction-based restriction fragment length polymorphism assay that used the restriction enzymes Rsa I and Dra I was used to detect wild-type and variant forms of the CYP2E1 gene.

RESULTS

Individuals homozygous for an allele of the CYP2E1 gene that is detected by Rsa I digestion (c2 allele) were found to have an increased risk of nasopharyngeal carcinoma (relative risk [RR] = 2.6; 95% confidence interval [CI] = 1.2-5.7); this effect was limited to nonsmokers (RR = 9.3; 95% CI = 2.7-32) and was not affected by alcohol consumption.

CONCLUSIONS

Our findings suggest that the CYP2E1 genotype is a determinant of nasopharyngeal carcinoma risk.

A population-based case-control study of the relationship between cigarette smoking and nasopharyngeal cancer (United States)

This case-control investigation, based on the Selected Cancers Study, assesses the association between cigarette smoking and nasopharyngeal cancer, a relatively rare neoplasm in the United States. Men who were diagnosed pathologically with nasopharyngeal cancer during 1984-88 were included as cases in the analysis if they were 15 to 39 years old in 1968, and lived in the areas covered by eight cancer registries in the US (n = 113). Control men were selected by random-digit telephone dialing (n = 1,910). Using logistic regression analysis with adjustment for potential confounding factors, it was found that relative to nonsmokers, the risks of nasopharyngeal cancer were 2.3 (95 percent confidence interval [CI] = 1.3-4.0) and 1.4 (CI = 0.8-2.6) for former and current smokers, respectively. Using pack-years as a measure, adjusted odds ratio (OR) estimates were 1.3, 1.8, 2.5, and 3.9 for smoking for less than 15, 15-29, 30-44, and 45 or more pack-years, respectively. When squamous cell carcinoma was used as an outcome, the smoking/nasopharyngeal-cancer association became stronger. The analysis did not show interactions between smoking and alcohol consumption, or prior nasal diseases. The results of this study suggest that cigarette smoking may be related to the occurrence of nasopharyngeal cancer (especially squamous cell carcinoma) among US men.

Tobacco use and nasopharyngeal carcinoma in a cohort of US veterans

The risk of nasopharyngeal carcinoma (NPC), a relatively rare neoplasm in the United States, was examined in relation to tobacco use in a cohort of nearly 250,000 US veterans whose mortality experience was followed for 26 years. A total of 48 NPC deaths were identified during the follow-up period. Current smokers had a nearly 4-fold increase in risk of NPC compared with non-users of any tobacco, with risk increasing to 6.4 among those smoking more than 2 packs daily. After adjustment for age and number of cigarettes smoked, risks were inversely associated with age at starting to smoke, with the highest risk observed among those who started smoking before age 15, although no clear trend associated with duration of smoking was observed. Former cigarette smokers had a small excess risk of NPC, but no association was detected for cigar/pipe users. This study adds strong evidence to the increasing literature linking cigarette smoking to NPC.

Head and neck carcinomas in patients under the age of forty years

From 1973 to 1988, 1,104 patients with head and neck carcinomas (excluding thyroid carcinoma) were admitted to the Yokohama City University Hospital, and among them, 48 (4.3%) were under the age of 40 years. We made a retrospective survey of these young patients. There were 36 males and 12 females. An increasing ratio of male to female was seen with increasing age. The primary site was most frequently the nasopharynx (29 cases), followed by the maxillary sinus (9 cases), and the tongue (4 cases). Squamous cell carcinoma in these young patients characteristically showed a low grade of differentiation.

Is persistent polyclonal B lymphocytosis caused by Epstein-Barr virus? A study with polymerase chain reaction and in situ hybridization

Previous reports of patients with persistent polyclonal B lymphocytosis have found associations with female sex, cigarette smoking, HLA-DR7 phenotype, and moderate elevation of peripheral blood polyclonal B lymphocytes. The presence of binucleated cells and atypical lymphocytes in the peripheral blood of these patients was highly suggestive of a viral infection, such as with the Epstein-Barr virus. We report a 47-year-old asymptomatic woman who was incidentally found to have persistent polyclonal B lymphocytosis and serum IgG against virus capsid antigen (VCA) and Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) of EBV. The presence of EBV was investigated in the peripheral blood lymphocytes from this patient by in situ hybridization and polymerase chain reaction methods. EBV DNA was demonstrated in the lymphocyte fraction by polymerase chain reaction, and it was further located in lymphoid cells by in situ hybridization. These results indicate that persistent polyclonal B lymphocytosis is strongly associated with EBV.

Familial aggregation of nasopharyngeal carcinoma and other malignancies. A clinicopathologic description

Nasopharyngeal carcinoma (NPC) occurred in five members in three generations of a white American family of Scandinavian descent. Six other family members had malignancies including malignant melanoma, malignant lymphoma, squamous cell carcinoma of the tongue, adenocarcinoma of the colon, and asynchronous bilateral in situ and invasive ductal carcinomas of the breast. There was also a history of autoimmune disorders and exposure to smoke, fumes, and chemicals in some family members. Regression analysis revealed a significant covariate risk for exposure to smoking, alcohol ingestion, dust, salted or spicy foods, and poorly ventilated conditions. According to segregation analysis, the susceptibility to nasopharyngeal carcinoma and other malignancies in this family was transmitted as an autosomal codominant characteristic. A specific histocompatibility antigen (HLA) haplotype of A1-B37-DR6 was associated with a predisposition for NPC, but no linkage was identified. Laboratory studies in selected family members did not reveal significantly elevated levels of Epstein-Barr virus antibodies or serum carcinoembryonic antigen. No specific karyotypic abnormalities were identified with peripheral blood chromosome analysis. This family was an example of apparent autosomal codominant susceptibility to NPC and other malignancies. The relationship of malignancy to the HLA haplotype of A1-B37-DR6, autoimmune disorders, and cytogenetic abnormalities was intriguing but not defined clearly.

Occupational and other non-dietary risk factors for nasopharyngeal carcinoma in Guangzhou, China

We conducted interviews on 306 histologically confirmed incident cases of nasopharyngeal carcinoma (NPC) occurring in residents of Guangzhou City, China, who were under the age of 50, and an equal number of age-, sex-, and neighborhood-matched controls. We also interviewed 110 mothers of patients under 45 and 139 mothers of controls who were matched to patients under age 45, to obtain information on childhood exposures of study subjects. Occupational exposure to products of combustion (RR = 2.4, p = 0.001) and cotton dust (RR = 0.3, P = 0.01) was independently related to risk of NPC. Use of tobacco products showed a moderate association with NPC; a lifetime exposure of 30+ pack-year equivalents conferred a 2-fold increased risk. A history of chronic ear or nose condition (rhinitis, sinusitis, nasal polyp, otitis media) was another risk factor for NPC (RR = 2.2, p less than 0.0005), and 18 cases compared to 3 controls had a first-degree relative with NPC (RR = 6.0, p = 0.001).