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ORIGINAL PAPER
Cancer Incidence Among Canadian Immigrants, 1980–1998:Results from a National Cohort Study
Sarah McDermott • Marie DesMeules • Roxanne Lewis •
Jenny Gold • Jennifer Payne • Bryan Lafrance •
Bilkis Vissandjee • Erich Kliewer • Yang Mao
Published online: 19 May 2010
� Her Majesty the Queen in Rights of Canada 2010
Abstract Canadian immigrants have lower overall cancer
risk than the Canadian-born population. Less is known
about risks for immigrant subgroups and site-specific
cancers. Linked administrative data sets were used to
compare cancer incidence between subgroups of immi-
grants to Canada and the general Canadian population. The
study involved 128,962 refugees and 241,010 non-refu-
gees. Standardized incidence ratios (SIRs) were calculated
for all-site and site-specific cancers by immigration
categories and regions of birth. Relative to the general
Canadian population, incidence of all-site cancer was
lower among immigrants overall, by sex and refugee status
(non-refugee SIRs 0.25: men, 0.24: women; refugee SIRs
0.31: both). Significantly higher SIRs resulted for liver,
nasopharyngeal and cervical cancers, including liver cancer
among South-East Asian and North-East Asian immi-
grants, and nasopharyngeal cancer among North-East
Asian non-refugees. Hypothesized explanations for varia-
tion in cancer incidence include earlier viral infection in
the country of origin.
Keywords Standardized incidence ratio � Cancer �Immigrant � Refugee � Non-refugee
S. McDermott (&)
Innovations and Trends Analysis Division, Strategic Initiatives
and Innovations Directorate, Public Health Agency of Canada,
785 Carling Avenue, A.L. 6809B, Ottawa, ON K1A 0K9,
Canada
e-mail: [email protected]
M. DesMeules
Health Determinants and Global Initiatives Division,
Strategic Initiatives and Innovations Directorate,
Public Health Agency of Canada, Ottawa, ON, Canada
R. Lewis � J. Gold � J. Payne � Y. Mao
Evidence and Risk Assessment Division,
Centre for Chronic Disease Prevention and Control,
Public Health Agency of Canada, Ottawa, ON, Canada
B. Lafrance
Health Statistics Division, Statistics Canada,
Ottawa, ON, Canada
B. Vissandjee
School of Nursing Sciences, University of Montreal,
Montreal, QC, Canada
E. Kliewer
Department of Epidemiology and Cancer Registry,
CancerCare Manitoba, Winnipeg, MB, Canada
E. Kliewer
Department of Community Health Sciences,
University of Manitoba, Winnipeg, MB, Canada
E. Kliewer
Cancer Control Research, British Columbia Cancer Agency,
Vancouver, BC, Canada
Y. Mao
Department of Epidemiology and Community Medicine,
University of Ottawa, Ottawa, ON, Canada
Present Address:J. Payne
Gender and Health Unit, Regions and Programs Branch,
Health Canada, Ottawa, ON, Canada
123
J Immigrant Minority Health (2011) 13:15–26
DOI 10.1007/s10903-010-9347-3
Introduction
The immigrant population is rapidly growing in Canada
and is a vital part of Canadian society. According to the
2006 Census, the Canadian population reached 31.6 mil-
lion, 1.2 million of whom immigrated to the country since
2001 [1]. This puts the total number of immigrants at 6.6
million, or 20.8% of the population. Canada has become an
increasingly multiethnic and multicultural country, [2] and
the health of its immigrants is an important part of the
overall health picture. Several studies have shown that
morbidity and mortality rates among recent immigrants are
lower than those among the general Canadian population
(although they may converge towards the latter over time)
[3, 4]. This ‘‘healthy immigrant effect’’ may be attributed
to a number of factors: first, people in good health are more
likely than those in poor health to emigrate; second,
employability, which is a factor in granting permission to
immigrate to Canada, requires a certain level of health; and
third, before they are admitted, immigrants undergo a
medical exam which is likely to screen out the very ill [5].
However, although they have a health advantage overall,
research has documented that immigrant populations may
show elevated rates of some diseases, such as certain
cancers, HIV/AIDS and tuberculosis [6–10].
Cancer is one of the leading causes of death in Canada.
Most previous cancer epidemiology studies of immigrants
have been based on cancer mortality, [9–11] and few reports
on incidence rates are available for this population. Scat-
tered reports from specific communities or for site-specific
cancers suggest variation in rates among immigrants, due in
part to region of origin, genetic susceptibility, and geo-
graphic, cultural and behavioural factors [12–18]. For
instance, Luo et al. [12] investigated the incidence of cancer
among Canadians of Chinese origin using data from the
Alberta Cancer Registry and the cancer registry in Shang-
hai. For cancers that were relatively common in China (e.g.,
nasopharyngeal, liver and esophageal cancer), the age-
standardized incidence rates among Chinese immigrants
were higher than in the Canadian-born population. How-
ever, the incidence of cancers less common in China (e.g.
prostate and breast cancer) was lower among Chinese
immigrants than among Canadians, but higher than in the
Chinese population. The same pattern has been found by Au
et al. [18] in their study of Hodgkin’s lymphoma among
Chinese immigrants in British Columbia. However, no
single study has examined cancer incidence rates among
immigrants across the country. An understanding of cancer
incidence patterns in Canadian immigrants and immigrant
subgroups would be of value for targeting public health
efforts and for health service planning.
The primary objective of this study was to examine the
extent to which Canadian immigrants, including some
subgroups (by sex and refugee status), and the general
Canadian population differ in their all-site and site-specific
cancer incidence rates. The secondary objective was to
assess whether these differentials, if they exist, vary
according to region of birth. In this paper we report cancer
incidence rates that are based on large, national, adminis-
trative data sets, which provided comprehensive and
detailed information for analysis. These data sets have
large enough samples to provide adequate statistical power
for many subgroups.
Methods
A historical cohort record linkage study design was used.
The sample frame consisted of immigration records col-
lected for administrative purposes on those achieving lan-
ded immigrant status (i.e., ‘‘landing’’) in Canada between
January 1, 1980 and December 31, 1990. This sample
frame did not include illegal immigrants or those denied
landed immigrant status. The immigrant cohorts were
stratified random samples from the sample frame. The
refugee sample consisted of every second record in this
group (n = 128,962) and the non-refugee sample consisted
of every fifth record in this group (n = 241,010). Refugees
were over-sampled to increase the statistical power for this
subgroup of immigrants. This random sample represented
approximately 20 and 50% of all non-refugee and refugee
immigrants who landed in Canada during the study period,
respectively.
Data Sources
Four national databases were used in this study
1. Canadian landed immigrant data from Citizenship and
Immigration Canada. The database is largely complete.
For example, the least complete variable for 1980
immigrants is date of birth, which is missing in
approximately 1,000 out of 143,476 records (0.7%)
[19].
2. Revenue Canada taxation data provides tax records of
all Canadian residents, including immigrants, who file
taxes. This is routinely linked to Canadian immigration
data by Statistics Canada to create the Longitudinal
Immigration Database (IMDB).
3. The Canadian Mortality Database (CMDB) contains
records of all deaths in Canada since 1950. The
database is mostly complete with coverage varying
from 98 to 100% for most variables [19].
4. The Canadian Cancer Database (CCDB) contains
records of cancer incidence since 1969, including
information such as type of cancer and date of
16 J Immigrant Minority Health (2011) 13:15–26
123
diagnosis. It is created in a form suitable for use in
record linkage studies, including standardization and
coding of name information.
The Generalized Iterative Record Linkage System, a
probabilistic linking system, was used to link the Canadian
immigration data (along with tax filing information from
the IMDB) to the CMDB and CCDB for the years 1980–
1998 using phonetically standardized immigrant names,
sex, date of birth and birthplace. The linkage and the
research conducted using the linked data were approved by
the University of Ottawa Research Ethics Board. The
methodology for the linkage has been reported on previ-
ously [20]. The method has also been verified in pilot
projects [19].
Data Analysis
Variable Selection
The variables used in the analysis included the following:
birth date, death date, sex, landing date, refugee status,
country of birth, date of cancer diagnosis, International
Classification of Diseases 9th edition (ICD-9) code for
cancer site, and annual tax filing. ICD-9 codes for cancer
site were as follows: all-site cancer 140–239, nasopharynx
147–148, stomach 151, colorectal 153–154, liver 155,
pancreas 157, lung 162–163, bladder 186–187, lymphoma
200–203, leukemia 204–206, breast (174–175) and cervix
180–181.
Person-year Calculation
Individuals were deemed to have entered the study on the
date of official landing as an immigrant in Canada,
although they may have entered Canada before being
granted this official status, and therefore before this date.
Total person-years of follow-up was defined by the
following formula:
Person years = (exit date - entry date)/365.242 days.
This was calculated by sex, refugee status, and country
of birth.
This study minimized losses to follow-up in the cohorts
through two methods: (1) Death dates recorded in the
CMDB were used as the exit date if the person died during
the study period. (2) The tax filing information was used to
adjust the estimate of residency in Canada for those
immigrants flagged as having filed taxes at least once
during the study period (approximately 84.7% of immi-
grant cohort). In this case, follow-up was continued until
the first of death date, cancer diagnosis date, last emigra-
tion date, last date the immigrant filed taxes or end of study
date (December 31, 1998). Those never flagged as having
filed taxes during the study period were followed until first
of death date, cancer diagnosis date, last emigration date or
end of study date.
Calculation of Standardized Incidence Ratios
Cancer incidence among immigrants was compared with
that of the general Canadian population who were resident
in Canada from 1980 to 1998 using an indirect age-stan-
dardization method. The analysis excluded 145 cancer cases
among non-refugees and 24 cases among refugees who were
diagnosed before ‘‘landing’’ in Canada. Expected counts of
cancer cases among the immigrant cohort were calculated
on the basis of age-specific cancer incidence rates in the
general population. The quotient of observed cases divided
by expected cases gives the standardized cancer incidence
ratio. The age-standardized incidence ratios (SIRs) for all-
site and site-specific cancers were stratified by sex, refugee
status, and country of birth. Sex-combined ratios were used
for SIRs that had cell counts of 15 or less. Corresponding
95% confidence intervals (CIs) were calculated to test the
statistical significance of the ratios.
All standardized ratios were based on a minimum of 5
observations. For some cancers in specific immigrant
groups, there were 15 or fewer cases; under these cir-
cumstances the results are not presented.
Results
The study cohorts included 128,962 refugees and 241,010
non-refugees, representing 50 and 20% of refugee and non-
refugee immigrants, respectively, who landed in Canada
between January 1, 1980, and December 31, 1990.
Most immigrants were young at landing time, with 46%
of non-refugees and 55% of refugees aged between 20 and
44 years (Table 1). High proportions of both refugees and
non-refugees came from South-East Asia and Western
Europe, whereas low proportions of both came from Oce-
ania and the Pacific Islands and the United States (USA).
However, larger proportions of refugees than non-refugees
came from South and Central America and Eastern Europe,
while larger proportions of non-refugees than refugees
came from North-East Asia and South Asia.
For all cancer sites combined, the SIR was significantly
lower for all immigrant subgroups than for Canadians
generally (Table 2). Refugees had a higher SIR than non-
refugees. Lower SIRs were also found for most site-
specific cancers, except for nasopharyngeal and liver cancer
(nasopharyngeal cancer, male non-refugee SIR = 4.03,
male refugee = 3.20, female non-refugee = 3.67; liver
cancer, male non-refugee = 1.41, male refugee = 3.09).
Among refugee women, the incidence of cervical cancer
J Immigrant Minority Health (2011) 13:15–26 17
123
was elevated, but the difference relative to the general
population was significant only among those 45-64 years
of age (SIR 1.58, 95% CI: 1.06–2.09). This was not the
case among non-refugee women in this age group (SIR
0.90, 95% CI: 0.67–1.12).
Tables 3 and 4 show the SIRs by geographic region of
birth and sex for non-refugees and refugees, respectively.
The SIRs for both groups for all-site cancer were low
among immigrants from all geographic regions compared
with Canadians in general. The SIRs varied by region of
birth for site-specific cancers. The SIR for liver cancer was
significantly elevated among immigrants from North-East
Asia and South-East Asia (SIR 3.40 and 2.07 for non-
refugee males and females respectively from North-East
Asia; 6.81 for refugee males from South-East Asia). The
SIR for cancer of the nasopharynx was also high among
non-refugees from North-East Asia (13.21 and 13.44 for
males and females, respectively).
Discussion
The findings of this study indicate that immigrants were at
lower risk for all-site cancer than the general Canadian
population. This confirms the impression of generally
lower cancer incidence and mortality rates among immi-
grants, [21–23] a finding that has been previously dis-
cussed in terms of the healthy immigrant effect [2, 3]. One
possible explanation for this lower risk is diet. Immigrants,
especially recent immigrants, may follow dietary patterns
that closely resemble those of their home country, and, in
some cases, these have been shown to be lower in satu-
rated fat consumption than the diet of the new host
country [24, 25]. This may have important implications
in the lower cancer incidence of immigrants. Another
possible explanation is the lower prevalence of smoking
among immigrants compared to the general Canadian
population [26].
Table 1 Distribution of immigrants in the sample frame and cohort with respect to linkage variables (age, sex and immigrant category) and
region of birth
Characteristics Refugees Non-refugees
Sample framea Cohortb Sample framea Cohortb
Count Percent Count Percent Count Percent Count Percent
Sex
Male 151,215 58.6 75,607 58.6 569,940 47.3 114,015 47.3
Female 106,710 41.4 53,355 41.4 635,113 52.7 126,995 52.7
Age group
0–19 92,172 35.7 46,080 35.7 351,105 29.1 70,227 29.1
20–44 142,080 55.1 71,040 55.1 549,313 45.6 109,860 45.6
45–64 22,116 8.6 11,060 8.6 234,932 19.5 46,981 19.5
65? 1,557 0.6 782 0.6 69,703 5.8 13,942 5.8
Region of birth
Western Europe 57,493 22.3 28,747 22.3 265,650 22.0 53,129 22.0
Eastern Europe and former Soviet Union 22,509 8.7 11,253 8.7 31,205 2.6 6,244 2.6
Middle East and North Africa 14,063 5.5 7,177 5.6 103,213 8.6 20,642 8.6
Africa 14,737 5.7 7,223 5.6 38,678 3.2 7,735 3.2
North-East Asia 12,444 4.8 6,223 4.8 200,203 16.6 40,043 16.6
South Asia 2,895 1.1 1,447 1.1 128,201 10.6 25,639 10.6
South-East Asia 100,868 39.1 50,434 39.1 162,902 13.5 32,581 13.5
Oceania and Pacific Islands 98 0.0 51 0.0 18,675 1.5 3,733 1.5
USA 700 0.3 349 0.3 69,948 5.8 13,992 5.8
Caribbean 833 0.3 417 0.3 92,348 7.7 18,470 7.7
South and Central America 31,065 12.0 15,532 12.0 92,428 7.7 18,486 7.7
Other/not stated 220 0.1 109 0.1 1,602 0.1 316 0.1
a The sample frame (1,462,978 records) includes all non-refugee and refugee immigrants who landed in Canada between January 1, 1980, and
December 31, 1990, except deportees and immigrants who had missing values for the linkage variables immigration category, sex and birth date
(\0.5% of records)b The immigrant cohorts are random samples of immigrants from the sample frame. The refugee sample consisted of every second record
(128,962 records). The non-refugee sample consisted of every fifth record (241,010 records)
18 J Immigrant Minority Health (2011) 13:15–26
123
Different patterns were found for site-specific cancers.
Elevated SIRs for cancer of the liver, cervix and naso-
pharynx were observed. This is consistent with the results
of previous research [12, 27–32]. Analysis by region of
birth revealed a high incidence of liver and nasopharyngeal
cancers (NPC) for immigrants from specific regions. The
high SIRs for liver cancer among South-East and North-
East Asian immigrants and for NPC among North-East
Asian immigrants are consistent with findings from previ-
ous studies [12, 20, 30, 31, 33–37]. The increased rates of
liver cancer observed in the present study may reflect the
high prevalence of viral hepatitis, especially of hepatitis B
(HBV) and C viral genotypes, in these regions. Immigrants
may have acquired the infection in early life, before
migration. A substantial proportion of those who are HBV-
infected become chronic carriers, which increases risk of
liver cancer, chronic active hepatitis and cirrhosis [38].
Liver cancer is also etiologically associated with con-
sumption of aflatoxin, a fungus endemic in the South-East
and North-East Asian regions in specific cereals, nuts, oils
and spices.
Our finding of a high incidence of NPC among immi-
grants from North-East Asia is also consistent with other
research [31]. Some studies have suggested a possible link
between NPC and genetic susceptilibility, [39] others have
suggested links with factors in early life, such as a diet of
highly salted foods and extensive exposure to dust or
smoke and infection with the Epstein-Barr virus [28, 39].
Cervical cancer rates among refugee women 45–64 years
of age exceeded rates among their Canadian counterparts.
This finding is relevant to the reported lower use of Pap
smear screening among immigrant women in Canada [40,
41]. Among non-refugee immigrant women of the same age,
the rate was no higher than among women in the general
Canadian population. There is evidence that incidence of
human papillomavirus (HPV), the virus that causes cervical
cancer, [42] as well as cervical cancer incidence and
mortality are associated with lower socioeconomic status,
[43–47] an issue possibly of greater concern to refugees.
Further, the distribution of HPV varies geographically, [48]
contributing to a potentially higher prevalence of carcino-
genic subtypes of HPV among some immigrants.
Table 2 Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for site-specific cancers among immigrants compared with the
Canadian general population, 1980–1998
Sex Cancer site (ICD-9) Non-refugees Refugees
N SIR 95% CI Na SIR 95% CI
Male All-sites (140–239) 2,464 0.25 0.24–0.26 703 0.31 0.28–0.33
Nasopharynx (147–148) 50 4.03* 2.91–5.14 19 3.20* 1.76–4.63
Stomach (151) 123 0.40 0.33–0.47 45 0.75 0.53–0.97
Colorectal (153–154) 299 0.27 0.24–0.30 71 0.34 0.26–0.42
Liver (155) 96 1.41* 1.13–1.70 59 3.09* 2.30–3.88
Pancreas (157) 50 0.22 0.16–0.28 18 0.40 0.22–0.59
Lung (162–163) 411 0.23 0.20–0.25 106 0.31 0.25–0.37
Bladder (186–187) 213 0.24 0.21–0.27 47 0.35 0.25–0.46
Lymphoma (200–203) 175 0.26 0.22–0.29 149 0.24 0.20–0.27
Leukemia (204–206) 86 0.24 0.19–0.29 32 0.22 0.14–0.29
Female All-sites (140–239) 2,400 0.24 0.23–0.25 641 0.31 0.34–0.29
Nasopharynx (147–148) 23 3.67* 2.17–5.18 NA
Stomach (151) 72 0.41 0.31–0.50 19 0.72 0.40–1.04
Colorectal (153–154) 259 0.24 0.21–0.27 46 0.31 0.22–0.40
Liver (155) 34 0.87 0.58–1.16 NA
Pancreas (157) 67 0.31 0.24–0.38 NA
Lung (162–163) 174 0.18 0.16–0.21 32 0.20 0.13–0.28
Breast (174–175) 678 0.32 0.30–0.35 183 0.38 0.33–0.44
Cervix (180–181) 126 0.68 0.56–0.79 70 1.07b 0.82–1.32
Bladder (186–187) 62 0.59 0.44–0.73 20 0.54 0.30–0.78
Lymphoma (200–203) 149 0.24 0.20–0.27 42 0.30 0.21–0.39
Leukemia (204–206) 60 0.21 0.16–0.26 NA
* Indicates that SIR is significantly greater than 1 (P \ 0.05)a NA indicates that the observed number of cases (N) is B15b Cervical cancer incidence is elevated among refugee women 45–64 years of age, SIR = 1.58 (1.06–2.09)
J Immigrant Minority Health (2011) 13:15–26 19
123
Table 3 Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for site-specific cancers in male and female non-refugees by
birth region compared with the Canadian general population, 1980–1998
Site Region of birth Males Females
N SIR 95% CI N SIR 95% CI
All-site Western Europe 573 0.30 0.28–0.33 571 0.29 0.27–0.32
Eastern Europe 185 0.37 0.32–0.42 207 0.32 0.28–0.37
South Asia 213 0.13 0.11–0.15 226 0.17 0.15–0.20
South-East Asia 261 0.24 0.21–0.26 266 0.21 0.19–0.24
North-East Asia 553 0.26 0.24–0.28 437 0.22 0.20–0.24
Middle East and North Africa 154 0.23 0.19–0.27 100 0.18 0.15–0.22
Africa 65 0.30 0.23–0.37 60 0.27 0.20–0.33
Caribbean 206 0.26 0.22–0.29 233 0.22 0.19–0.25
Americas 95 0.27 0.22–0.32 126 0.27 0.22–0.32
Oceania and Pacific Islands 17 0.21 0.11–0.30 26 0.29 0.18–0.40
Nasopharynx North-East Asia 33 13.21* 8.70–17.72 16 13.44* 6.85–20.02
Stomach Western Europe 32 0.54 0.35–0.73 18 0.48 0.26–0.71
North-East Asia 42 0.63 0.44–0.82 18 0.52 0.28–0.75
Colorectal Western Europe 78 0.37 0.29–0.45 84 0.38 0.30–0.47
Eastern Europe 21 0.37 0.21–0.53 22 0.30 0.18–0.43
South-East Asia 28 0.22 0.14–0.30 29 0.22 0.14–0.30
Caribbean 19 0.22 0.12–0.32 22 0.20 0.12–0.36
North-East Asia 78 0.33 0.25–0.40 61 0.29 0.22–0.36
Liver North-East Asia 50 3.40* 2.46–4.35 16 2.07* 1.06–3.09
Lung Western Europe 99 0.30 0.24–0.36 36 0.21 0.14–0.28
Eastern Europe 36 0.40 0.27–0.53 NA
South-East Asia 67 0.33 0.25–0.40 23 0.19 0.11–0.27
North-East Asia 110 0.27 0.22–0.32 54 0.28 0.21–0.36
Bladder Western Europe 46 0.82 0.59–1.06 18 0.88 0.48–1.29
Eastern Europe 20 1.34 0.75–1.92 NA
Lymphoma Western Europe 35 0.25 0.17–0.34 37 0.30 0.20–0.40
South Asia 34 0.33 0.22–0.45 NA
South-East Asia 23 0.32 0.19–0.45 NA
North-East Asia 21 0.15 0.09–0.21 17 0.14 0.07–0.21
Leukemia Western Europe 35 0.48 0.32–0.63 37 0.63 0.43–0.83
South Asia 34 0.67 0.45–0.90 NA
South-East Asia 23 0.60 0.36–0.85 NA
North-East Asia 21 0.30 0.17–0.43 17 0.32 0.17–0.47
Breast Western Europe NA 182 0.45 0.39–0.52
Eastern Europe NA 47 0.35 0.25–0.45
South Asia NA 63 0.23 0.18–0.29
South-East Asia NA 67 0.25 0.19–0.31
North-East Asia NA 101 0.24 0.19–0.29
Middle East and North Africa NA 42 0.34 0.24–0.45
Caribbean NA 60 0.27 0.20–0.34
Americas NA 38 0.40 0.27–0.53
Cervical cancer South-East Asia NA 16 0.69 0.35–1.03
* Indicates that SIR is significantly greater than 1 (P \ 0.05)a NA indicates that the observed number of cases (N) is B15. Those regions not included in the table for a particular cancer site also have 15 or
fewer cases
20 J Immigrant Minority Health (2011) 13:15–26
123
It is of significance to note that the three cancers for
which elevated SIRs were found can be related to earlier
viral infection in the country of origin (i.e. hepatitis B and
C viruses, Epstein-Barr virus and HPV). These represent
exceptions to the healthy immigrant effect. The option of
enhanced screening and other preventive measures by
health service practitioners and at point of immigration
could be further studied with the aim of maximizing pre-
vention, early detection and treatment of cancer. In the case
of liver cancer, for example, some immigrants from South-
east and North-east Asia have been found to have a lower
level of knowledge about hepatitis virus infection [35, 38].
Hislop et al. [38] surveyed Chinese immigrants in British
Columbia and found that most respondents were aware that
HBV can cause cirrhosis and liver cancer, but possessed
lower level of knowledge about how HBV is spread. Of the
total sample, 57% had been tested for HBV; of these, 7% of
men and 5% of women had been told that they were
carriers. Preventive measures against liver cancer for vul-
nerable immigrant subgroups might include selective
screening for hepatitis B and C, targeted educational
approaches and immunization.
Similarly, early and regular screening is an important
preventive method for reducing the morbidity and mortal-
ity associated with cervical cancer, but many immigrant
women are unaware of early detection methods and their
importance, as well as the signs and symptoms of cervical
cancer [49]. Rates of screening for cervical cancer tend to
increase with length of stay in Canada for Black and His-
panic women and for White women from Europe, but less
so among immigrant women of Asian background even
after many years of residence [41]. One exploratory study
of cultural influences on breast and cervical screening
among Vietnamese-Canadian women found that study
participants valued their bodies as private and not to be
openly discussed, which served as barriers to them seeking
screening [50]. There is some evidence that educational
programs tailored towards specific immigrant groups can
be effective at increasing participants’ awareness of cancer
and its methods of prevention or early detection [51].
Table 4 Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for site-specific cancers in male and female refugees by birth
region compared with the Canadian general population, 1980–1998
Site Region of birth Males Females
N SIR 95% CI N SIR 95% CI
All-site Eastern Europe 267 0.35 0.30–0.39 248 0.37 0.32–0.41
South-East Asia 267 0.29 0.26–0.33 267 0.30 0.26–0.34
North-East Asia 49 0.32 0.23–0.41 23 0.21 0.20–0.48
Middle East and North Africa 31 0.28 0.18–0.38 20 0.25 0.14–0.36
Africa 26 0.32 0.20–0.45 16 0.38 0.19–0.57
Americas 52 0.24 0.17–0.30 54 0.24 0.18–0.30
Colorectal Eastern Europe 30 0.42 0.27–0.57 NA
South-East Asia 20 0.25 0.14–0.36 23 0.34 0.14–0.36
Liver South-East Asia 50 6.81* 4.92–8.69 NA
Lung Eastern Europe 28 0.24 0.15–0.33 NA
South-East Asia 49 0.37 0.27–0.48 19 0.28 0.15–0.40
North-East Asia 18 0.59 0.32–0.86 NA
Bladder Eastern Europe 17 0.90 0.47–1.33 NA
Lymphoma Eastern Europe 30 0.33 0.14–0.32 19 0.43 0.24–0.62
South-East Asia 25 0.23 0.14–0.32 NA
Leukemia Eastern Europe 30 0.65 0.42–0.88 19 0.74 0.41–1.08
South-East Asia 25 0.41 0.25–0.57 NA
North-East Asia 17 0.32 0.17–0.47 NA
Breast Western Europe NA 43 0.45 0.32–0.59
Eastern Europe NA 79 0.47 0.36–0.57
South-East Asia NA 65 0.33 0.25–0.41
Americas NA 17 0.32 0.17–0.47
Cervical South-East Asia NA 32 1.15 0.75–1.55
* Indicates that SIR is significantly greater than 1 (P \ 0.05)a NA indicates that the observed number of cases (N) is B15. Those regions not included in the table for a particular cancer site also have 15 or
fewer cases
J Immigrant Minority Health (2011) 13:15–26 21
123
While the use of linkage in the study methodology
provided accurate and reliable information on the cohort of
immigrants and minimized the information biases that
often occur in self-reported records, limitations exist.
Firstly, use of the general Canadian population, which
includes immigrants, as a comparison group may dilute the
effects under study. Further, the study did not address risk
factors for cancer or their social determinants. Risk factors,
such as behaviour (i.e. smoking) and stress, and protective
factors, such as personal strength and social resources,
often interact in complex ways with social determinants of
health, including socioeconomic status, to influence out-
comes. The lack of data on these variables limits our ability
to explain observed differences in cancer incidence.
Another limitation of record linkage studies, including
this one, is false non-links due to immigrant name mis-
spellings, name changes and accidental reversals. These
could lead to an underestimation of cancer incidence rates
among immigrants. The rigour of the record linkage
approach used (e.g., multiple names, name and birth date
reversals, name change information from the CIC data-
base), and the consistency of the findings with those of
other studies, suggest the results presented in this report
remain valid despite this limitation.
Finally, bias may occur if immigrants die in another
country, since deaths of Canadians abroad are not generally
included in Canadian vital statistics (with the exception of
some American states). Use of Canadian tax records min-
imized this loss to follow-up bias by adjusting the estimate
for the immigrants who continued to reside in Canada.
Validation of the use of tax filing information to adjust the
estimate of residency in Canada was undertaken using
observed deaths in the CMDB. Validation revealed that
among those who stopped filing taxes after at least one
filing, few death dates were observed in CMDB after date
of last filing, suggesting these immigrants may have moved
to another country. On the other hand, among those who
never filed taxes, 3,494 deaths were observed (out of a total
8,990 deaths among the immigrant cohort), demonstrating
that many of these immigrants remained and died in
Canada, despite never having filed taxes. Immigrants who
never file taxes may represent an especially vulnerable
group (with respect to socio-economic status, integration,
etc.) and should not be excluded from record linkage
studies on this basis. For this reason, tax filing information
was used to adjust for loss to follow-up only among those
who filed taxes at least once.
Overall, study results demonstrate that immigrants to
Canada bring their own unique health characteristics,
which may be quite different from those of the general
Canadian population and are also likely to differ according
to their region of birth. Findings are important for further
cancer etiologic research, policy development and service
planning. Enhanced health promotion and disease preven-
tion strategies could be further explored, including primary
and secondary prevention programs, to encourage use of
available health services (e.g. cancer screening programs),
and to meet the needs of immigrants.
Acknowledgments The Canadian Population Health Initiative, of
the Canadian Institute for Health Information, Citizenship and
Immigration Canada, Statistics Canada and the Public Health Agency
of Canada (PHAC) sponsored this study. Data were provided to
PHAC by Citizenship and Immigration Canada, Statistics Canada and
the Quebec Cancer Registry. The authors also wish to acknowledge
Mrs. Martha Fair, formerly of Statistics Canada, for her invaluable
contribution to the data linkage process for this study.
Appendix
See Table 5.
Table 5 Group of countries
Western Europe Andorra
Austria
Azores
Belgium
Canary Islands
Channel Islands
Cyprus
Denmark
England
Finland
France
German Democratic Republic
Germany, Federal Republic of
Gibraltar
Greece
Holy See (Vatican City)
Iceland
Ireland, Republic of
Italy
Liechtenstein
Luxembourg
Madeira
Malta
Monaco
Netherlands, the
Northern Ireland
Norway
Poland
Portugal
San Marino (Italy)
Scotland
Spain
22 J Immigrant Minority Health (2011) 13:15–26
123
Table 5 continued
Sweden
Switzerland
United Kingdom and Colonies
Wales
Eastern Europe
and Former
Soviet Union
Albania
Bosnia-Hercegovina
Bulgaria
Croatia
Czech Republic
Czechoslovakia
Estonia
Fyr Macedonia
Hungary
Latvia
Lithuania
Romania
Slovak Republic
Slovenia
Turkey
Yugoslavia
Union of Soviet Socialist Republics
Afghanistan
Azerbaijan
Belarus
Kazakhstan
Kyrgyzstan
Tadjikistan
Turkmenistan
Uzbekistan
Moldova
Mongolia, People’s Republic of
Armenia
Georgia
Russia
Ukraine
South Asia Bangladesh
Pakistan
Sikkim (Asia)
Sri Lanka
Maldives, Republic of
India
Nepal
Bhutan
South-East Asia Cambodia
Indonesia, Republic of
Malaysia
Macao
Hong Kong
Hong Kong SAR
Table 5 continued
Singapore
Brunei
Laos
North Vietnam
Papau New Guinea
Thailand
Tibet
Vietnam, Socialist Republic of
Myanmar (Burma)
Papau
North-East Asia Japan
Taiwan
China, People’s Republic of
Philippines
Korea, People’s Democratic Republic of
Korea, Republic of
Middle East and
North Africa
Israel
Jordan
Palestinian Authority (Gaza/West Bank)
Qatar
Saudi Arabia
Syria
United Arab Emirates
Yemen, People’s Democratic Republic of
Lebanon
Oman
Kuwait
Iran
Iraq
Bahrain
Algeria
Libya
Morocco
Tunisia
Egypt
Africa Angola
Cape Verde Islands
Zambia
Namibia
Rwanda
Sierra Leone
Zimbabwe
Botswana, Republic of
South Africa, Republic of
Lesotho
Swaziland
Mozambique
Central African Republic
Chad
J Immigrant Minority Health (2011) 13:15–26 23
123
Table 5 continued
Burundi
Congo, Democratic Republic of
Zaire, Republic of
Burkina Faso
Liberia
Mali, Republic of
Cameroon, Federal Republic of
Guinea, Equatorial
Guinea, Republic of
Guinea-Bissau
Ivory Coast, Republic of
Ghana
Niger, Republic of the
Nigeria
Sao Tome e Principe (near Guinea)
Western Sahara
Mauritania
Benin, Republic of
Senegal
Gambia
Gabonese Republic
Togo, Republic of
Malawi
Tanzania, United Republic of
Kenya
Uganda
Somalia, Democratic Republic of
Ethiopia
Erythrea
Sudan, Democratic Republic of
Djibouti, Republic of
Caribbean Anguilla
Barbados
Bermuda
Dominican Republic
Grenada
Guadeloupe
Haiti
Jamaica
Martinique
Montserrat
Netherlands Antilles, the
Nevis
Puerto Rico
St. Kitts-Nevis
St. Lucia
St. Vincent and the Grenadines
Trinidad & Tobago, Republic of
Table 5 continued
Turks and Caicos Islands
Virgin Islands, British
Virgin Islands, U.S.
Antigua and Barbuda
Aruba
Bahama Islands, The
Cayman Islands
Cuba
Dominica
Americas Canada
United States of America
St. Pierre et Miquelon
Greenland
Newfoundland
Mexico
Belize
Honduras
Nicaragua
Costa Rica
El Salvador
Guatemala
Panama Canal Zone
Panama, Republic of
Argentina
Colombia
Ecuador
Marinas
Paraguay
Peru
Surinam
Uruguay
Venezuela
Falkland Islands
French Guyana
Guyana
Bolivia
Brazil
Chile
Oceania and Pacific Islands Australia
New Caledonia
New Zealand
Cook Islands
Fiji
French Polynesia
Tonga
Tuvalu
St. Helena
Samoa, American
24 J Immigrant Minority Health (2011) 13:15–26
123
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