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Ethnic inequalities in cancer incidence and mortality: census-linked cohort studies with 87 million years of person-time follow-up

View Article: PubMed Central - PubMed

ABSTRACT

Background: Cancer makes up a large and increasing proportion of excess mortality for indigenous, marginalised and socioeconomically deprived populations, and much of this inequality is preventable. This study aimed to determine which cancers give rise to changing ethnic inequalities over time.

Methods: New Zealand census data from 1981, 1986, 1991, 1996, 2001, and 2006, were all probabilistically linked to three to five subsequent years of mortality (68 million person-years) and cancer registrations (87 million person years) and weighted for linkage bias. Age-standardised rate differences (SRDs) for Māori (indigenous) and Pacific peoples, each compared to European/Other, were decomposed by cancer type.

Results: The absolute size and percentage of the cancer contribution to excess mortality increased from 1981–86 to 2006–11 in Māori males (SRD 72.5 to 102.0 per 100,000) and females (SRD 72.2 to 109.4), and Pacific females (SRD −9.8 to 42.2) each compared to European/Other.

Results: Specifically, excess mortality (SRDs) increased for breast cancer in Māori females (linear trend p < 0.01) and prostate (p < 0.01) and colorectal cancers (p < 0.01) in Māori males. The incidence gap (SRDs) increased for breast (Māori and Pacific females p < 0.01), endometrial (Pacific females p < 0.01) and liver cancers (Māori males p = 0.04), and for cervical cancer it decreased (Māori females p = 0.03). The colorectal cancer incidence gap which formerly favoured Māori, decreased for Māori males and females (p < 0.01).

Results: The greatest contributors to absolute inequalities (SRDs) in mortality in 2006–11 were lung cancer (Māori males 50 %, Māori females 44 %, Pacific males 81 %), breast cancer (Māori females 18 %, Pacific females 23 %) and stomach cancers (Māori males 9 %, Pacific males 16 %, Pacific females 20 %). The top contributors to the ethnic gap in cancer incidence were lung, breast, stomach, endometrial and liver cancer.

Conclusions: A transition is occurring in what diseases contribute to inequalities. The increasing excess incidence and mortality rates in several obesity- and health care access-related cancers provide a sentinel warning of the emerging drivers of ethnic inequalities. Action to further address inequalities in cancer burden needs to be multi-pronged with attention to enhanced control of tobacco, obesity, and carcinogenic infectious agents, and focus on addressing access to effective screening and quality health care.

Electronic supplementary material: The online version of this article (doi:10.1186/s12885-016-2781-4) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Ethnic inequalities in smoking, obesity, alcohol and screening examples of mediators for excess cancer mortality, New Zealand. Note: Smoking prevalence rates use the definition of regular current smoking of 1+ cigarette per day and there was some slight variation between censuses in the questions for ethnicity and smoking. The crude obesity prevalence rates from National Nutrition Surveys (NNS) and New Zealand Health Surveys (NZHS) use an obesity definition of a BMI of ≥30, except for Māori and Pacific peoples before 2000 when it was ≥32. The age group was 15+ year olds except for in 1977 (20–64 years) and 1989 (15–74 years). European/Other obesity figures in 1977 and 1989 are estimated from the total population. Alcohol consumption is from the NZHS and the New Zealand Drug and Alcohol Survey. Breast and cervical screening coverage is from the Independent Monitoring Reports at www.nsu.govt.nz
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Fig1: Ethnic inequalities in smoking, obesity, alcohol and screening examples of mediators for excess cancer mortality, New Zealand. Note: Smoking prevalence rates use the definition of regular current smoking of 1+ cigarette per day and there was some slight variation between censuses in the questions for ethnicity and smoking. The crude obesity prevalence rates from National Nutrition Surveys (NNS) and New Zealand Health Surveys (NZHS) use an obesity definition of a BMI of ≥30, except for Māori and Pacific peoples before 2000 when it was ≥32. The age group was 15+ year olds except for in 1977 (20–64 years) and 1989 (15–74 years). European/Other obesity figures in 1977 and 1989 are estimated from the total population. Alcohol consumption is from the NZHS and the New Zealand Drug and Alcohol Survey. Breast and cervical screening coverage is from the Independent Monitoring Reports at www.nsu.govt.nz

Mentions: These issues are relevant in New Zealand, where the prevalence of tobacco smoking, obesity, human papilloma virus (HPV) infection, H. Pylori infection and chronic hepatitis B infection is substantially higher in Māori and Pacific peoples compared with European/Other, and screening coverage rates are lower and vary over time (Fig. 1). Such large ethnic differences in risk factors makes New Zealand a potentially valuable case study to explore the trends in ethnic inequalities in cancer burden.Fig. 1


Ethnic inequalities in cancer incidence and mortality: census-linked cohort studies with 87 million years of person-time follow-up
Ethnic inequalities in smoking, obesity, alcohol and screening examples of mediators for excess cancer mortality, New Zealand. Note: Smoking prevalence rates use the definition of regular current smoking of 1+ cigarette per day and there was some slight variation between censuses in the questions for ethnicity and smoking. The crude obesity prevalence rates from National Nutrition Surveys (NNS) and New Zealand Health Surveys (NZHS) use an obesity definition of a BMI of ≥30, except for Māori and Pacific peoples before 2000 when it was ≥32. The age group was 15+ year olds except for in 1977 (20–64 years) and 1989 (15–74 years). European/Other obesity figures in 1977 and 1989 are estimated from the total population. Alcohol consumption is from the NZHS and the New Zealand Drug and Alcohol Survey. Breast and cervical screening coverage is from the Independent Monitoring Reports at www.nsu.govt.nz
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5037611&req=5

Fig1: Ethnic inequalities in smoking, obesity, alcohol and screening examples of mediators for excess cancer mortality, New Zealand. Note: Smoking prevalence rates use the definition of regular current smoking of 1+ cigarette per day and there was some slight variation between censuses in the questions for ethnicity and smoking. The crude obesity prevalence rates from National Nutrition Surveys (NNS) and New Zealand Health Surveys (NZHS) use an obesity definition of a BMI of ≥30, except for Māori and Pacific peoples before 2000 when it was ≥32. The age group was 15+ year olds except for in 1977 (20–64 years) and 1989 (15–74 years). European/Other obesity figures in 1977 and 1989 are estimated from the total population. Alcohol consumption is from the NZHS and the New Zealand Drug and Alcohol Survey. Breast and cervical screening coverage is from the Independent Monitoring Reports at www.nsu.govt.nz
Mentions: These issues are relevant in New Zealand, where the prevalence of tobacco smoking, obesity, human papilloma virus (HPV) infection, H. Pylori infection and chronic hepatitis B infection is substantially higher in Māori and Pacific peoples compared with European/Other, and screening coverage rates are lower and vary over time (Fig. 1). Such large ethnic differences in risk factors makes New Zealand a potentially valuable case study to explore the trends in ethnic inequalities in cancer burden.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Background: Cancer makes up a large and increasing proportion of excess mortality for indigenous, marginalised and socioeconomically deprived populations, and much of this inequality is preventable. This study aimed to determine which cancers give rise to changing ethnic inequalities over time.

Methods: New Zealand census data from 1981, 1986, 1991, 1996, 2001, and 2006, were all probabilistically linked to three to five subsequent years of mortality (68 million person-years) and cancer registrations (87 million person years) and weighted for linkage bias. Age-standardised rate differences (SRDs) for Māori (indigenous) and Pacific peoples, each compared to European/Other, were decomposed by cancer type.

Results: The absolute size and percentage of the cancer contribution to excess mortality increased from 1981–86 to 2006–11 in Māori males (SRD 72.5 to 102.0 per 100,000) and females (SRD 72.2 to 109.4), and Pacific females (SRD −9.8 to 42.2) each compared to European/Other.

Results: Specifically, excess mortality (SRDs) increased for breast cancer in Māori females (linear trend p < 0.01) and prostate (p < 0.01) and colorectal cancers (p < 0.01) in Māori males. The incidence gap (SRDs) increased for breast (Māori and Pacific females p < 0.01), endometrial (Pacific females p < 0.01) and liver cancers (Māori males p = 0.04), and for cervical cancer it decreased (Māori females p = 0.03). The colorectal cancer incidence gap which formerly favoured Māori, decreased for Māori males and females (p < 0.01).

Results: The greatest contributors to absolute inequalities (SRDs) in mortality in 2006–11 were lung cancer (Māori males 50 %, Māori females 44 %, Pacific males 81 %), breast cancer (Māori females 18 %, Pacific females 23 %) and stomach cancers (Māori males 9 %, Pacific males 16 %, Pacific females 20 %). The top contributors to the ethnic gap in cancer incidence were lung, breast, stomach, endometrial and liver cancer.

Conclusions: A transition is occurring in what diseases contribute to inequalities. The increasing excess incidence and mortality rates in several obesity- and health care access-related cancers provide a sentinel warning of the emerging drivers of ethnic inequalities. Action to further address inequalities in cancer burden needs to be multi-pronged with attention to enhanced control of tobacco, obesity, and carcinogenic infectious agents, and focus on addressing access to effective screening and quality health care.

Electronic supplementary material: The online version of this article (doi:10.1186/s12885-016-2781-4) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus