title: Worldwide malaria incidence and cancer mortality are inversely associated.
abstract: BACKGROUND
  Investigations on the effects of malaria infection on cancer mortality are limited except for the incidence of Burkitt's lymphoma (BL) in African children. Our previous murine lung cancer model study demonstrated that malaria infection significantly inhibited tumor growth and prolonged the life span of tumor-bearing mice. This study aims to assess the possible associations between malaria incidence and human cancer mortality.
  
  
  METHODS
  We compiled data on worldwide malaria incidence and age-standardized mortality related to 30 types of cancer in 56 countries for the period 1955-2008, and analyzed their longitudinal correlations by a generalized additive mixed model (GAMM), adjusted for a nonlinear year effect and potential confounders such as country's income levels, life expectancies and geographical locations.
  
  
  RESULTS
  Malaria incidence was negatively correlated with all-cause cancer mortality, yielding regression coefficients (log scale) of -0.020 (95%CI: -0.027,-0.014) for men (P< 0.001) and-0.020 (95%CI: -0.025,-0.014) for women (P< 0.001). Among the 29 individual types of cancer studied, malaria incidence was negatively correlated with colorectum and anus (men and women), colon (men and women), lung (men), stomach (men), and breast (women) cancer.
  
  
  CONCLUSIONS
  Our analysis revealed a possible inverse association between malaria incidence and the mortalities of all-cause and some types of solid cancers, which is opposite to the known effect of malaria on the pathogenesis of Burkitt's lymphoma. Activation of the whole immune system, inhibition of tumor angiogenesis byPlasmodiuminfection may partially explain why endemic malaria might reduce cancer mortality at the population level.
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou Science Park, 510530 Guangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Qin
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital, 181 Longwood Ave, Boston, MA 02115 USA.
authors.forename: Changzhong
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou Science Park, 510530 Guangzhou, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Chen
authors.affiliation: Boston University, Boston, MA 02215 USA.
authors.forename: Ran
authors.initials: R
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital, Guangzhou Medical University, 151 Yanjiang Road, 510120 Guangzhou, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Ou-Yang
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital, Guangzhou Medical University, 151 Yanjiang Road, 510120 Guangzhou, China.
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou Science Park, 510530 Guangzhou, China.
authors.forename: Siting
authors.initials: S
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou Science Park, 510530 Guangzhou, China.
authors.forename: Zhengxiang
authors.initials: Z
authors.lastname: He
authors.affiliation: Department of Bioengineering, McGill University, Montreal, QC H3A 0C3 Canada.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital, Guangzhou Medical University, 151 Yanjiang Road, 510120 Guangzhou, China.
authors.forename: Jianxing
authors.initials: J
authors.lastname: He
authors.affiliation: Boston University, Boston, MA 02215 USA.
authors.forename: Pinghua
authors.initials: P
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital, Guangzhou Medical University, 151 Yanjiang Road, 510120 Guangzhou, China.
authors.forename: Nanshan
authors.initials: N
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou Science Park, 510530 Guangzhou, China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Chen
keywords: Cancer mortality; Epidemiological data; Generalized additive mixed model (GAMM); Malaria incidence; Regression analysis