Mortality Of Nasopharyngeal Carcinoma Research Articles

Nasopharyngeal carcinoma incidence and mortality in China, 2013

BackgroundWe estimated the incidence and mortality of nasopharyngeal carcinoma (NPC) in China in 2010 according to the data of 145 domestic population-based cancer registries in 2014, and no such reports since then. Hence, to further and better understand its epidemiology in China and to provide more precise scientific information for its control and prevention in China, we analyzed the NPC incidence and mortality of 255 domestic population-based cancer registries, and estimated the national rates in 2013 again.MethodsNPC incidence and mortality data of 255 domestic cancer registries in 2013, accepted by the 2016 National Cancer Registry Annual Report, were collected and collated, and the indices of NPC such as the numbers of new cases and deaths, crude rates, age-standardized rates, and truncated rates of incidence and mortality were calculated and analyzed. The incidence and mortality in China and its constituent areas were estimated according to the national population in 2013.ResultsAn estimated 42,100 new cases and 21,320 deaths were attributed to NPC in China in 2013, accounting for 1.14% of all new cancer cases and 0.96% of all cancer-related deaths that year in China. Crude incidence and mortality of NPC were 3.09/100,000 and 1.57/100,000, respectively. World age-standardized incidence and mortality were 2.17/100,000 and 1.08/100,000, respectively. The incidence and mortality of males were obviously higher than those of females and slightly higher in urban areas than in rural areas. Among seven Chinese administrative regions, NPC incidence and mortality were obviously higher in South China than in other regions and lowest in North China. Top 3 incidence and mortality provinces and registering areas all located in South China. The age-specific incidence and mortality rose quickly from age 25–29 and 35 to 39 years, respectively, peaked at different ages and varied by location.ConclusionsThese results demonstrated that NPC incidence and mortality in China in 2013 were also at high levels worldwide, which suggested that its control and prevention should be enhanced.

Prognostic role of neutrophil-lymphocyte ratio in nasopharyngeal carcinoma: A meta-analysis.

BackgroundInflammatory markers are used to predict prognosis of nasopharyngeal carcinoma (NPC). Previous reports of neutrophil-to-lymphocyte ratio (NLR) and NPC mortality are inconsistent. This study aimed to quantify the prognostic impact of NLR on NPC.MethodsThe primary outcome was overall survival (OS), and the secondary outcomes were disease-specific survival (DSS), progression-free survival (PFS) and distant metastasis-free survival (DMFS). We systematically searched electronic databases, identified articles reporting an association between NLR and NPC prognosis. Hazard ratios (HRs) and 95% confidence intervals (CIs) were extracted, and pooled HRs for each outcome were estimated using random effect models.ResultsNine studies enrolling 5397 patients were included in the analyses. NLR greater than the cutoff value was associated with poor overall survival (HR 1.51, 95% CI 1.27–1.78), disease-specific survival (HR 1.44, 95% CI 1.22–1.71), progression-free survival (HR 1.53, 95% CI 1.22–1.90), and distant metastasis-free survival (HR 1.83, 95% CI 1.14–2.95).ConclusionsElevated NLR predicts worse OS, DSS, PFS and DMFS in patients with NPC.

Spatial and temporal patterns of nasopharyngeal carcinoma mortality in China, 1973–2005

We fitted generalized linear models using data from three national retrospective surveys on cause of death in China to explore the spatial and temporal patterns of nasopharyngeal carcinoma (NPC) mortality over the period 1973 to 2005. The results suggest that there was a significant decrease in NPC mortality in China over time (p < 0.0001), the mortality rate ratio (RR) for the two later time periods were 0.59 (95% CI: 0.55–0.64) for 1990–1992 and 0.42 (95% CI: 0.39–0.45) for 2004–2005 compared to that of 1973–1975. Residents living in the South China areas have an elevated risk of mortality from NPC compared to those living in North China across all three time periods, with the RR being 4.96 (95% CI: 4.31–5.70) in 1973–1975, 12.83 (95% CI: 10.73–15.34) in 1990–1992 and 15.20 (95% CI: 12.34–18.72) in 2004–2005. Although NPC mortality in most areas of China has reduced to very low levels, the widening geographical disparities in NPC mortality are still noteworthy. It may be necessary to target public health policies to address the widening geographical disparities in NPC mortality.

Global trends in incidence and mortality of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a rare malignancy with an extraordinarily skewed geographic distribution worldwide. Although decreasing trends in incidence and mortality of NPC have been sporadically reported in some high-risk areas, no comprehensive description of the global trends has ever been made. We accessed incidence (1970–2007) and mortality (1970–2013) data from multiple sources, with the main ones being the Cancer Incidence in Five Continents (CI5) series and the World Health Organization (WHO) cancer mortality database. During the entire period studied, age-standardized incidence rates (ASIRs) of NPC decreased significantly in southern and eastern Asia, north America and Nordic countries with average annual percent changes (AAPCs) of −0.9% to −5.4% in males and −1.1% to −4.1% in females. Declines in age-standardized mortality rates (ASMRs) are even more remarkable and extensive, with AAPCs varying from −0.9% and −0.8% to −3.7% and −6.5% in males and females, respectively. Decreasing trends in NPC incidence are probably due to tobacco control, changes in diets and economic development. Declines in mortality rates are the results of advancements in diagnostic and radiotherapy techniques, as well as decreased incidence rates.

Smoking and nasopharyngeal carcinoma mortality: a cohort study of 101,823 adults in Guangzhou, China.

BackgroundNasopharyngeal carcinoma (NPC), also known as Cantonese cancer, is rare worldwide, but has particularly high incidence in North Africa and Southeast Asia, especially in Guangdong, China, such as Guangzhou. Tobacco causes head and neck cancers, but nasopharyngeal carcinoma is not included as causally related to smoking in the 2014 United States Surgeon General’s report. Prospective evidence remains limited. We used Guangzhou Occupational Cohort data to conduct the first and robust prospective study on smoking and NPC mortality in an NPC high-risk region.MethodsInformation on demographic characteristics and smoking status was collected through occupational health examinations in factories and driver examination stations from March 1988 to December 1992. Vital status and causes of deaths were retrieved until the end of 1999. Cox proportional hazard model was used to assess the association of smoking with NPC mortality.ResultsOf 101,823 subjects included for the present analysis, 34 NPC deaths occurred during the average 7.3 years of follow up. The mean age (standard deviation) of the subjects was 41 (5.7) years. Compared with never smokers, the hazard ratio (HR) of NPC mortality was 2.95 (95 % confidence interval 1.01–8.68; p = 0.048) for daily smokers and 4.03 (1.29–12.58; p = 0.016) for smokers with more than 10 pack-years of cumulative consumption, after adjusting for age, sex, education, drinking status, occupation and cohort status and accounting for smoking-drinking interaction. The risk of NPC mortality increased significantly with cigarettes per day (p for trend = 0.01) and number of pack-years (p for trend = 0.02).ConclusionsIn this first and largest cohort in a high NPC risk region, smoking was associated with higher NPC mortality. The findings have shown statistically significant dose–response trend between smoking amount and smoking cumulative consumption and the risk of NPC mortality, but due to the small event number, further studies with larger sample size are needed to confirm the findings in the present study. Our results support that smoking is one of the risk factors likely to be causally associated with NPC mortality.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1902-9) contains supplementary material, which is available to authorized users.

Mortality Characteristic and Prediction of Nasopharyngeal Carcinoma in China from 1991 to 2013.

To analyze the mortality distribution of nasopharyngeal carcinoma in China from 1991 to 2013, to predict the mortality in the ensuing five years, and to provide evidence for prevention and treatment of nasopharyngeal carcinoma. Mortality data for Nasopharyngeal Carcinoma in China from 1991 to 2013 were used to describe its epidemiological characteristics, such as the change of the standardized mortality rate, sex and age differences, urban-rural differences. Trend-surface analysis was used to study the geographical distribution of the mortality. Curve estimation, time series, gray modeling, and joinpoint regression were used to predict the mortality for the ensuing five years in the future. In China, the standardized mortality rate of Nasopharyngeal Carcinoma increased with time from 1996, reaching the peak values of 1.45 /105 at the year of 2002, and decreased gradually afterwards. With males being 1.51 times higher than females, and the city had a higher rate than the rural during the past two decades. The mortality rate increased from age 40. Geographical analysis showed the mortality rate increased from middle to southern China. The standardized mortality rate of Nasopharyngeal Carcinoma is falling. The regional disease control for Nasopharyngeal Carcinoma should be focused on Guangdong province of China, and the key targets for prevention and treatment are rural men, especially after the age of 40. The mortality of Nasopharyngeal Carcinoma will decrease in the next five years.

Levels of plasma Epstein-Barr virus DNA prior and subsequent to treatment predicts the prognosis of nasopharyngeal carcinoma.

The level of Epstein-Barr virus DNA (EBV-DNA) in the plasma prior and subsequent to treatment is a reliable biomarker for the screening, diagnosis, monitoring and prognosis of nasopharyngeal carcinoma (NPC). The present retrospective study aimed to determine whether pre- and post-treatment levels of plasma EBV-DNA were predictive of survival in a large sample of patients with NPC. The level of plasma EBV-DNA in 637 NPC patients prior and subsequent to treatment was determined by quantitative polymerase chain reaction. The value of pre- and post-treatment plasma EBV-DNA in predicting the survival of NPC patients was then analyzed. The results revealed that pre-treatment plasma EBV-DNA loads were significantly higher in patients with NPC than those in healthy controls (P<0.001). The percentage of patients with positive plasma EBV-DNA was markedly higher prior to treatment (70.64%; median, 1150 copies/ml; range, 0-9.75×106 copies/ml) than following treatment (25.99%; median, 0 copies/ml; range, 0-3.83×106 copies/ml) (P<0.001). Patients with a high plasma EBV-DNA load presented with a higher clinical tumor classification, lymph node status, metastatic status and overall cancer stage. The risk of NPC relapse and mortality was higher in patients with pre-treatment plasma EBV-DNA levels of ≥1,500 copies/ml than that in patients with <1,500 copies/ml. Furthermore, the risk of relapse and mortality was higher in patients with positive post-treatment plasma EBV-DNA than in patients with negative post-treatment plasma EBV-DNA. Detectable post-treatment plasma EBV-DNA was the most significant prognostic factor to affect relapse-free survival, whilst metastasis was the prognostic factor with the greatest effect on overall survival. These data indicated that pre- and post-treatment levels of plasma EBV-DNA were able to predict the prognosis of NPC. This finding may provide novel references for research and clinical practice.

Time trends of nasopharyngeal carcinoma in urban Guangzhou over a 12-year period (2000-2011): declines in both incidence and mortality.

Nasopharyngeal carcinoma (NPC) is an uncommon disease in most countries but occurs with much greater frequency in southern China. This study aimed to examine the secular trends of NPC in urban Guangzhou over the time period of 2000-2011 using data from the Guangzhou Cancer Registry. Age-adjusted annual incidence rates of NPC were calculated by the direct method using the WHO World Standard Population (1960) as the reference. The average annual percentage change (AAPC) was used as an estimate of the trend. A total of 7,532 new cases of NPC and 3,449 related deaths were registered. In both genders, the peak incidence occurred in the 50- to 59-year age group, and this age distribution pattern remained similar throughout. The AAPC in NPC incidence rates was -3.26% (95% CI: -5.4%--1.1) for males and -5.74% (95% CI: -8.9%--2.5) for females, resulting in a total decrease of 39.3% (from 22.14 to 13.44 per 100,000 population) for males and 48.6% (from 10.1 to 5.18 per 100,000 population) for females over this 12-year period. The AAPCs in NPC mortality rates were -4.62% (95%CI: -3.5%--5.7) for males and -6.75% (95% CI: -5.2%--8.3) for females, resulting in a total decrease of -46.1% (from 12.1 to 6.54 per 100,000 population) for males and 51.7% (from 4.14 to 2.00 per 100,000 population) for females. The age-adjusted incidence and mortality rates of NPC declined during 2000-2011 in urban Guangzhou but remained high. Future efforts to improve prevention, early detection and treatment strategies are needed.

Nasopharyngeal carcinoma incidence and mortality in China in 2010.

Nasopharyngeal carcinoma (NPC) is common in South China. Although regional epidemiological data on NPC in China is available, national epidemiological data have been unavailable up to now. The goal of this study was to analyze the NPC incidence and mortality data in some domestic cancer registries, estimate these rates in China in 2010, and provide scientific information that can be harnessed for NPC control and prevention. To accomplish this goal, NPC incidence and mortality data for 2010 were collected from 145 Chinese cancer registries from which data were included in the 2013 National Cancer Registry Annual Report. Such indices as its incident and death numbers, crude rates, age-standardized rates and truncated rates were calculated and analyzed. The incidence and mortality in China and constituent areas were estimated according to the national population in 2010. An estimated 41,503 new cases and 20,058 deaths were attributed to NPC in China in 2010, accounting for 1.34% of all new cancer cases and 1.03% of all cancer-related deaths that year in China. Crude incidence and mortality were 3.16/100,000 and 1.53/100,000, respectively. World age-standardized incidence and mortality were 2.44/100,000 and 1.18/100,000, respectively. Incidence and mortality were higher among males than among females and slightly higher in urban areas than in rural areas. Among seven Chinese administrative regions, NPC incidence and mortality were obviously higher in South China than in other regions and lowest in North China. The male and female age-specific incidence and mortality both rose quickly from age 25-29 years, but peaked at different ages and varied by location. These results demonstrated that NPC incidence and mortality in China especially in South China were at high levels in the world, and suggested that control and prevention efforts should be enhanced.

Nasopharyngeal carcinoma incidence and mortality in China in 2009

Nasopharyngeal carcinoma (NPC) is rare globally but common in China and exhibits a distinct ethnic and geographic distribution. In 2009, the National Central Cancer Registry in China provided real-time surveillance information on NPC. Individual NPC cases were retrieved from the national database based on the ICD-10 topography code C11. The crude incidence and mortality of NPC were calculated by sex and location (urban/rural). China's population in 1982 and Segi's world population structures were used to determine age-standardized rates. In regions covered by the cancer registries in 2009, the crude incidence of NPC was 3.61/100,000 (5.08/100,000 in males and 2.10/100,000 in females; 4.19/100,000 in urban areas and 2.42/100,000 in rural areas). Age-standardized incidences by Chinese population (ASIC) and Segi's world population (ASIW) were 2.05/100,000 and 2.54/100,000, respectively. The crude mortality of NPC was 1.99/100,000 (2.82/100,000 in males and 1.14/100,000 in females; 2.30/100,000 in urban areas and 1.37/100,000 in rural areas). The age-standardized mortalities by Chinese population (ASMC) and world population (ASMW) were 1.04/100,000 and 1.35/100,000, respectively. The incidence and mortality of NPC were higher in males than in females and higher in urban areas than in rural areas. Both age-specific incidence and mortality were relatively low in persons younger than 30 years old, but these rates dramatically increased. Incidence peaked in the 60-64 age group and mortality peaked in the over 85 age group. Primary and secondary prevention, such as lifestyle changes and early detection, should be carried out in males and females older than 30 years of age.

Trends in the survival of patients with nasopharyngeal carcinoma between 1976 and 2005 in Sihui, China: a population-based study

Both the incidence and mortality of nasopharyngeal carcinoma (NPC) have decreased in Hong Kong and Taiwan but not in mainland China. The goal of this study was to analyze trends in NPC patient survival between 1976 and 2005 in Sihui, an area of mainland China with a population at high risk for NPC. A total of 1,761 patients diagnosed with NPC between 1976 and 2005 according to the records of Sihui Cancer Registry were followed to the end of 2006. We determined their observed and relative survival rates and used Cox proportional hazards regression analysis to predict prognosis. Our results showed that the 5-year and 10-year observed survival rates of NPC patients in Sihui were 50.5% and 36.9%, respectively, and the median survival time was 5.1 years. The 5-year observed survival rate of NPC patients diagnosed after 2000 was 69.8%, significantly higher than that of patients diagnosed between 1976 and 1985 (42.5%; P < 0.001, relative risk = 0.28). Similarly, the 5-year relative survival rate was 84.8% between 2000 and 2005 but 51.8% between 1976 and 1985. Besides date of diagnosis, other prognostic factors included patient sex and age and NPC clinical stage and histologic type. The relative risks of death from NPC were 0.76 [95% confidence interval (CI): 0.65–0.90] for female comparing to male and 1.28 (95% CI: 1.00–1.64) for WHO type I comparing to WHO types II and III. For the eldest age group and the latest clinical stage group, the relative risks were 2.22 (95% CI: 1.73–2.84) and 3.41 (95% CI: 2.34–4.49), respectively. Our results indicate that the survival of NPC patients in Sihui has significantly increased in recent years and this increase is not influenced by patient's sex, age, histologic type, and clinical stage. A reduction in mortality rate is expected in coming years.

Lower mortality from nasopharyngeal cancer in The Netherlands since 1970 with differential incidence trends in histopathology

Nasopharyngeal carcinoma (NPC) is rare in western countries albeit affected by common and unrelated phenomena: smoking less in men, more in women and immigration from China and North Africa. We studied trends in NPC incidence, tumour morphology, survival and mortality in order to assess progress against this cancer. A trend analysis was performed with nationwide incidence and survival data (from The Netherlands Cancer registry in 1989-2009), followed by analysis of mortality (data from Statistics Netherlands) covering the period 1970-2009, and calculating estimated percentages of change (EAPC) in both. According to the WHO classification we distinguished keratinizing SCC (WHO-I), differentiated (WHO-IIA) and undifferentiated (WHO-IIB) non-keratinizing carcinoma. NPC incidence significantly decreased since 1989, especially in males (EAPC 1989-2009: -1.3; 95% CI: -2.5, -0.2) and in patients with keratinizing SCC (WHO-I) (EAPC: -3.6; 95% CI: -5.3, -1.8). By contrast, the incidence of differentiated non-keratinizing tumours (WHO-IIA) significantly increased in the same period (EAPC: 9.6; 95% CI: 5.6, 13.5). One- and three-year relative survival, as an indicator of disease-specific survival increased slightly from 79% to 81% and from 57% to 65% since 1989. NPC mortality significantly decreased since 1970 (EAPC: -1.2; 95% CI: -1.8, -0.5) and more pronounced since 1989 (EAPC: -3.0; 95% CI: -4.3, -1.6). During the past two decades, the incidence of NPC in The Netherlands decreased mainly by less keratinizing, supposedly smoking-related NPC (WHO-I). However, the incidence of non-keratinizing NPC (WHO-IIA, B) increased, most likely due to EBV infection and thus related to higher immigration levels of people from high-incidence areas.

Trends in Nasopharyngeal Carcinoma Mortality in China, 1973-2005

Nasopharyngeal carcinoma (NPC) is a disease with distinct ethnic and geographic distribution. The incidence of NPC in Chinese residing in Asia has declined over the last few decades, but NPC mortality trends in the entire Chinese population over time have not been systematically evaluated. In this study, we examined NPC mortality at the national level in China between 1973-2005. Mortality rates were derived from the databases of national retrospective surveys on cancer mortality conducted in the periods of 1973-1975, 1990-1992, and 2004-2005, respectively. NPC was classified according to the International classification of diseases. Age-adjusted mortality rates were calculated by direct standardization according to the world standard population. Trends in rates were evaluated by age, gender, geographic areas, and socioeconomic status. From 1973 to 2005, there was a general trend of decrease in NPC mortality in China, with higher rates in the south on a downward trend in the north. The age-standardized NPC mortality rates were 2.60 per 100,000 in 1973-1975, 1.94 per 100,000 in 1990-1992, and 1.30 per 100,000 in 2004-2005, respectively. The trend was similar in both men and women, in both urban and rural areas, but the declining rates in females were more remarkable than in males. The mortality rates were higher for the age groups above 50 years than those less than 50 years of age, both showing downward trend over 30-year period. In summary, the overall NPC mortality has consistently decreased in China over the past three decades, particularly in women and in old adults.

Activation of AKT is associated with metastasis of nasopharyngeal carcinoma

Although radiotherapy results of nasopharyngeal carcinoma (NPC) at an early stage are better than other tumors, there is still a portion of patients with NPC who die before 5 years after the treatment; the underlying mechanism remains to be further understood. This study aims to investigate the mechanism by which NPC cells escape from irradiation. Patients with NPC at stage I was included in this study. All the patients were treated with irradiation. NPC biopsies were obtained from each patient before and 1 week after the start of radiotherapy. Expression of AKT in NPC tissue was assessed by Western blotting. NPC cell line, SUNE-1 cells, was treated with irradiation. The levels of AKT in SUNE-1 cells were also assessed. The frequency of apoptotic SUNE-1 cells was evaluated by flow cytometry. The levels of AKT were markedly increased in NPC tissue after treatment with irradiation, which was significantly correlated with NPC metastasis and mortality. After irradiation, NPC cell line, SUNE-1 cells, expressed higher levels of AKT than control cells. The knockdown of AKT in SUNE-1 cells markedly increased apoptotic cell rate. Radiotherapy can increase the levels of AKT in NPC cells that are associated with NPC metastasis and increase in mortality.

The Prediction of Nasopharyngeal Carcinoma Mortality Based on Soil Element Levels in China

The relationship between the mortality of nasopharyngeal carcinoma (NPC) and soil trace elements of 29 regions of China was investigated. A total of 29 elements (i.e., Mn, Na, K, Mg, Ca, Sr, Ba, Hg, Pb, Se, In, Yb, Lu, Th, U, Sn, Ti, Zr, Hf, Bi, Ta, Te, Br, I, As, Cr, Cu, Fe, and Zn) were considered. A hybrid strategy called genetic algorithm-partial least squares was used to screen out important elements. As a result, only six elements, i.e., Mn, Ti, Mg, K, Na, and I, were picked out, based on which, a PLS model containing two latent variables exhibited the best performance. According to whether the mortality is larger than 2/100,000 (2 × 10(-5)), all the 29 regions were divided into the low-mortality group with 23 regions and the high-mortality group with six regions. Based on the optimal PLS model, all high-mortality regions were successfully classified while only two low-mortality regions were misclassified, i.e., an accuracy of 93%, implying that the selected six elements are effective and successful for predicting the NPC mortality of a region.

Trends in incidence and mortality of nasopharyngeal carcinoma over a 20–25 year period (1978/1983–2002) in Sihui and Cangwu counties in southern China

BackgroundNasopharyngeal carcinoma (NPC) is a rare malignancy in most parts of the world but is common in southern China. A recent report from the Hong Kong Cancer Registry, a high-risk area for NPC in southern China, showed that incidence rate decreased by 29% for males and by 30% for females from 1980–1999, while mortality rate decreased by 43% for males and 50% for females. Changing environmental risk factors and improvements in diagnosis and treatment were speculated to be the major factors contributing to the downward trend of the incidence and mortality rates of NPC. To investigate the secular trends in different Cantonese populations with different socio-economic backgrounds and lifestyles, we report the incidences and mortality rates from two population-based cancer registries in Sihui and Cangwu counties from 1978–2002.MethodsIncidence and mortality rates were aggregated by 5-year age groups and 5 calendar years. To adjust for the effect of difference in age composition for different periods, the total and age-specific rates of NPC incidence and mortality rate were adjusted by direct standardization according to the World Standard Population (1960). The Estimated Annual Percentage Change (EAPC) was used as an estimate of the trend.ResultsThe incidence rate of NPC has remained stable during the recent two decades in Sihui and in females in Cangwu, with a slight increase observed in males in Cangwu from 17.81 to 19.76 per 100,000. The incidence rate in Sihui is 1.4–2.0 times higher during the corresponding years than in Cangwu, even though the residents of both areas are of Cantonese ethnicity. A progressive decline in mortality rate was observed in females only in Sihui, with an average reduction of 6.3% (p = 0.016) per five-year period.ConclusionTo summarize, there is great potential to work in the area of NPC prevention and treatment in southern China to decrease NPC risk and improve survival risk rates in order to reduce M:I ratios. Future efforts on effective prevention, early detection and treatment strategies were also discussed in this paper. Furthermore, the data quality and completeness also need to be improved.

Changing epidemiology of nasopharyngeal carcinoma in Hong Kong over a 20-year period (1980-99): an encouraging reduction in both incidence and mortality.

Epidemiological data from the Hong Kong Cancer Registry for the period 1980-99 were analyzed. Altogether 21,768 new cases of nasopharyngeal carcinoma (NPC) and 8,664 related deaths were registered. In both genders, the peak incidence occurred in the 50-59 years age group, and this age distribution pattern remained similar throughout. The age-standardized incidence rate steadily decreased from 28.5 in 1980-84 to 20.2 in 1995-99 per 100,000 males, and from 11.2-7.8 per 100,000 females, resulting in a total decrease of 29% for males and 30% for females over this 20-year period. The magnitude of total decrease in NPC mortality amounted to 43% and 50%, respectively, as the age-standardized mortality rate steadily decreased from 13.7 in 1980-84 to 7.8 in 1995-99 per 100,000 males, and from 4.5-2.2 per 100,000 females. The age-standardized mortality/incidence ratio also decreased from the peak of 0.48 in 1980-84 to 0.39 in 1995-99 for males, and from 0.40-0.29 for females. Females had significantly lower age-standardized incidence (male/female ratio 2.5-2.6, p < 0.01) and mortality (male/female ratio 3.0-3.5, p< 0.01) throughout the whole period. Furthermore, females had consistently lower mortality/incidence ratio: 0.29 vs. 0.39 in 1995-99. These data are highly suggestive of significant improvement in prevention and control of NPC in Hong Kong. Closer scrutiny of the differences in intrinsic and extrinsic factors between the genders might help to show important factors affecting oncogenesis and prognosis. Possible ways for further reduction of incidence and mortality are discussed.

Trace element content in drinking water of nasopharyngeal carcinoma patients

Chinese in the Xiangxi region of Hunan province in China have a high incidence of nasopharyngeal carcinoma (NPC). For analyzing the relation between NPC and trace elements, the concentrations of 7 trace elements in drinking water (well water) of high- and low-incidence areas were measured (75 samples). The results showed that the concentrations of Ni, Zn and Cd in drinking water of high-incidence areas were significantly higher than those in low-incidence areas. Especially, the Ni level in drinking water had a significant positive correlation with NPC mortality. These observations are consistent with earlier studies. We also found a highly positive correlation between Ni pH value in drinking water and NPC mortality. This suggests that only considering the ion concentration in drinking water is not enough, we should also pay attention to the pH of the drinking water when we study the relation between NPC and trace elements. Because the pH of the medium can strongly affect trace element chemical characteristics and its metabolic state in living systems, the M pH (M, metal concentration) may be an important factor worthy of further research.