title: Secular trends of salted fish consumption and nasopharyngeal carcinoma: a multi-jurisdiction ecological study in 8 regions from 3 continents.
abstract: BACKGROUND
  Despite salted fish being a classical risk factor of Nasopharyngeal Carcinoma (NPC), whether secular trends in salted fish consumption worldwide accounted for changes in NPC rates were unknown. The relationship between vegetable and cigarette consumption to NPC risk worldwide were also largely uncertain. We investigated the longitudinal trends in standardised NPC incidence/mortality rates across 8 regions and their associations with secular trends in salted fish, vegetable and tobacco consumptions.
  
  
  METHODS
  Age standardised mortality rate (ASMR) and age standardised incidence rate (ASIR) of NPC were obtained from the WHO cancer mortality database and Hong Kong Cancer Registry. Per capita consumption of salted fish, tobacco and vegetables in Hong Kong and 7 countries (China, Finland, Japan, Portugal, Singapore, United Kingdom and United States) were obtained from the Food and Agriculture Organization of the United Nation (FAO) and Hong Kong Trade and Census Statistics. Pearson correlation and multivariate analysis were performed to examine both crude and adjusted associations.
  
  
  RESULTS
  There were markedly decreasing trends of NPC ASIR and ASMR in Hong Kong over the past three decades, which were correlated with corresponding secular changes in salted fish consumption per capita (Pearson r for 10 cumulative years : ASIR = 0.729 (male), 0.674 (female); ASMR = 0.943 (male), 0.622 (female), all p < 0.05 except for female ASMR). However such associations no longer correlated with adjustments for decreasing tobacco and increasing vegetable consumption per capita (Pearson r for 10 cumulative years: ASIR = 2.007 (male), 0.339 (female), ASMR = 0.289 (male), 1.992 (female), all p > 0.05). However, there were no clear or consistent patterns in relations between NPC ASIR and ASMR with salted fish consumption across 7 regions in 3 continents.
  
  
  CONCLUSIONS
  Our results do not support the notion that changes in salted fish consumption had played an important role in explaining secular trends of NPC rates in Hong Kong and worldwide. Further studies should explore other lifestyle and genetic factors. However, our findings do support the potentially protective effects of vegetable consumption against NPC.
authors.affiliation: School of Public Health, University of Hong Kong, Hong Kong, China.
authors.forename: Hiu-Ying
authors.initials: HY
authors.lastname: Lau
authors.forename: Chit-Ming
authors.initials: CM
authors.lastname: Leung
authors.forename: Yap-Hang
authors.initials: YH
authors.lastname: Chan
authors.forename: Anne Wing-Mui
authors.initials: AW
authors.lastname: Lee
authors.forename: Dora Lai-Wan
authors.initials: DL
authors.lastname: Kwong
authors.forename: Maria Li
authors.initials: ML
authors.lastname: Lung
authors.forename: Tai-Hing
authors.initials: TH
authors.lastname: Lam
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002277:Carcinoma; D002648:Child; D002675:Child, Preschool; D004032:Diet / Q000009:adverse effects*; D005260:Female; D005399:Fishes; D005519:Food Preservation / Q000379:methods; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000453:epidemiology* / Q000209:etiology; D012907:Smoking / Q000009:adverse effects; D012965:Sodium Chloride; D014675:Vegetables; D055815:Young Adult
chemical_list: D012965:Sodium Chloride