Elsevier

The Lancet Oncology

Volume 11, Issue 8, August 2010, Pages 741-752
The Lancet Oncology

Fast track — Articles
Body-mass index and cancer mortality in the Asia-Pacific Cohort Studies Collaboration: pooled analyses of 424 519 participants

https://doi.org/10.1016/S1470-2045(10)70141-8Get rights and content

Summary

Background

Excess bodyweight is an established risk factor for several types of cancer, but there are sparse data from Asian populations, where the proportion of overweight and obese individuals is increasing rapidly and adiposity can be substantially greater for the same body-mass index (BMI) compared with people from Western populations.

Methods

We examined associations of adult BMI with cancer mortality (overall and for 20 cancer sites) in geographic populations from Asia and from Australia and New Zealand (ANZ), within the Asia-Pacific Cohort Studies Collaboration, by use of Cox regression analysis. Pooled data from 39 cohorts (recruitment 1961–99, median follow-up 4 years) were analysed for 424 519 participants (77% Asian; 41% female; mean recruitment age 48 years) with individual data on BMI.

Findings

After excluding those with follow-up of less than 3 years, 4872 cancer deaths occurred in 401 215 participants. Hazard ratios for cancer sites with increased mortality risk in obese (BMI ≥30 kg/m2) compared with normal weight participants (BMI 18·5–24·9 kg/m2) were: 1·21 (95% CI 1·09–1·36) for all-cause cancer (excluding lung and upper aerodigestive tract), 1·50 (1·13–1·99) for colon, 1·68 (1·06–2·67) for rectum, 1·63 (1·13–2·35) for breast in women 60 years or older, 2·62 (1·57–4·37) for ovary, 4·21 (1·89–9·39) for cervix, 1·45 (0·97–2·19) for prostate, and 1·66 (1·03–2·68) for leukaemia (all after left censoring at 3 years). The increased risk associated with a 5-unit increase in BMI for those with BMI of 18·5 kg/m2 or higher was 1·09 (95% CI 1·04–1·14) for all cancers (excluding lung and upper aerodigestive tract). There was little evidence of regional differences in relative risk of cancer with higher BMI, apart from cancers of the oropharynx and larynx, where the association was inverse in ANZ and absent in Asia.

Interpretation

Overweight and obese individuals in populations across the Asia-Pacific region have a significantly increased risk of mortality from cancer. Strategies to prevent individuals from becoming overweight and obese in Asia are needed to reduce the burden of cancer that is expected if the obesity epidemic continues.

Funding

National Health and Medical Research Council of Australia, Health Research Council of New Zealand, and Pfizer Inc.

Introduction

More than 1 billion people worldwide are overweight or obese, conditions that are a main risk factor for chronic diseases, including some cancers.1 Because of its widespread prevalence and effect on many health conditions, excess weight is ranked as the seventh most important contributor to mortality worldwide.2 As in the west, many Asian countries such as China, South Korea, Thailand, and Singapore are experiencing a steep rise in the prevalence of obesity in their populations,3 although compared with the west, the prevalence remains low.3, 4

Excess weight and obesity are associated with increased risk of several site-specific cancers, with a 5 kg/m2 higher body-mass index (BMI) typically associated with risk ratios in the range of 1·10–1·60.5 The evidence linking excess weight and obesity to cancer has mainly come from Western populations, with few data from Asians,6, 7, 8 in whom adiposity can be substantially greater for the same BMI.9, 10 Furthermore, the background prevalence of other dietary and lifestyle risk factors for cancer might also differ between Western and Asian populations,11 which could affect the association between excess weight and subsequent cancer risk. Recent meta-analyses of Asian data, mainly from Japan or Hawaii, show that higher BMI is associated with increased risks of cancer of the female breast5 and colorectum12 in populations from Asia or the Asia-Pacific region, compared with North America, Europe, and Australia.

The present study, which uses data from the Asia-Pacific Cohort Studies Collaboration (APCSC), has two aims: to examine associations between BMI and site-specific cancer mortality in populations of the Asia-Pacific region, and to assess whether the magnitude and direction of the associations are consistent between geographic populations in Asia and outside Asia (Australia and New Zealand) which, to the best of our knowledge, has not been previously systematically examined using individual participant data.

Section snippets

Procedures

The APCSC is a large, collaborative, data-pooling project involving data from more than 600 000 participants in the Asia-Pacific region. Details of the collaboration have been described elsewhere.13, 14 Briefly, studies were eligible for inclusion if they had the following criteria: a study population from the Asia-Pacific region; a prospective cohort study design; at least 5000 person-years of follow-up; date of birth (or age), sex, and blood pressure recorded at baseline; date of death or age

Results

Individual participant data were included from 39 cohorts (webtable 2), consisting of 424 519 people, of whom 326 387 (77%) were from Asian cohorts and 175 364 (41%) were female; mean age was 48 years; and median year of recruitment was 1992 in cohorts from Asia and ANZ. Comparing baseline characteristics with the Asian cohorts, individuals from ANZ had higher BMI (mean 26·6 kg/m2 [SD 3·7] in men and 26·0 kg/m2 [4·9] in women vs 23·0 kg/m2 [2·7] in men and 22·6 kg/m2 [3·1] in women from Asia);

Discussion

In the present study, based on data from more than 400 000 individuals from 39 prospective cohort studies in the Asia-Pacific region, we found that among individuals with a BMI higher than 18·5 kg/m2, there was a positive and continuous association between BMI and all-cancer mortality, such that a 5 kg/m2 increase in BMI was associated with a relative risk (HR) of 1·09 (95% CI 1·04–1·14), after excluding cases of lung and UADT cancer, which had a negative association with BMI. Compared with

Glossary

Left censoring
Exclusion of study participants with follow-up time less than a certain duration

References (37)

  • EC Rush et al.

    Body size, body composition and fat distribution: comparative analysis of European, Maori, Pacific Island and Asian Indian adults

    Br J Nutr

    (2009)
  • M Ezzati et al.

    Role of smoking in global and regional cancer epidemiology: current patterns and data needs

    Int J Cancer

    (2005)
  • Y Ning et al.

    A quantitative analysis of body mass index and colorectal cancer: findings from 56 observational studies

    Obes Rev

    (2009)
  • Determinants of cardiovascular disease in the Asian Pacific region: protocol for a collaborative overview of cohort studies

    CVD Prevention

    (1999)
  • M Woodward et al.

    Cohort profile: the Asia Pacific Cohort Studies Collaboration

    Int J Epidemiol

    (2006)
  • Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies

    Lancet

    (2004)
  • DF Easton et al.

    Floating absolute risk: an alternative to relative risk in survival and case-control analysis avoiding an arbitrary reference group

    Stat Med

    (1991)
  • G Whitlock et al.

    Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies

    Lancet

    (2009)
  • Cited by (205)

    View all citing articles on Scopus
    *

    Prof Jamrozik died in March, 2010

    Listed in webappendix

    View full text