Adulthood consumption of preserved and nonpreserved vegetables and the risk of nasopharyngeal carcinoma: a systematic review

Int J Cancer. 2006 Sep 1;119(5):1125-35. doi: 10.1002/ijc.21946.


The incidence rates of nasopharyngeal carcinoma (NPC) are dramatically higher in certain regions of Asia compared to the rest of the world. Few risk factors for NPC are known; however, in contrast to the hypothesized health benefits of nonpreserved vegetables, it is thought that preserved vegetable intake may play a role in contributing to the higher incidence of NPC in high-risk regions. Therefore, the purpose of this study was to systematically review the epidemiologic evidence on the associations between adulthood intake of preserved and nonpreserved vegetables and NPC risk. A search of the epidemiological literature from 1966 to 2004 was performed using several bibliographic databases, including PubMed and the Chinese Biomedical Literature Database System. There were no language restrictions. Meta-analysis was conducted to obtain pooled odds ratios (ORs) for the highest-versus-lowest categories of preserved and nonpreserved vegetable intake. A total of 16 case-control studies were identified in the search. Results showed that highest-versus-lowest preserved vegetable intake was associated with a 2-fold increase in the risk of NPC (Random Effects Odds Ratio (RE OR) 2.04; 95% Confidence Limits (CL) 1.43, 2.92). Conversely, high nonpreserved vegetable intake was associated with 36% decrease in the risk of NPC (RE OR 0.64; 95% CL 0.48, 0.85). Findings for both preserved and nonpreserved vegetables were consistent across vegetable type and by country of study. Further research in high-risk areas to gain insight into the risk associated with preserved vegetables and protection associated with nonpreserved vegetables may advance understanding of NPC and yield clues for prevention.

Publication types

  • Meta-Analysis
  • Research Support, N.I.H., Extramural
  • Review
  • Systematic Review

MeSH terms

  • Adult
  • Carcinoma / epidemiology*
  • Carcinoma / etiology*
  • Carcinoma / prevention & control
  • China / epidemiology
  • Feeding Behavior
  • Food Preservation*
  • Humans
  • Incidence
  • Middle Aged
  • Nasopharyngeal Neoplasms / epidemiology*
  • Nasopharyngeal Neoplasms / etiology*
  • Nasopharyngeal Neoplasms / prevention & control
  • Odds Ratio
  • Risk Assessment
  • Risk Factors
  • Vegetables*