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Ethnic differences in the time trend of female breast cancer incidence: Singapore, 1968-2002.

Sim X, Ali RA, Wedren S, Goh DL, Tan CS, Reilly M, Hall P, Chia KS - BMC Cancer (2006)

Bottom Line: While our analyses provided some evidence that an age-drift model described the trend seen in the Indians, age-period-cohort model and age-cohort model had the best fit for the Chinese and Malays aged 25 to 79 respectively.The observed dissimilarity among ethnic groups suggests ethnic differences in exposure or response to certain risk factors.It is likely that longer and subtler differences in childbearing trends and other risk factors may further explain these ethnic differences.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Molecular Epidemiology, National University of Singapore and Genome Institute of Singapore, Singapore. cmesx@nus.edu.sg <cmesx@nus.edu.sg>

ABSTRACT

Background: From 1968 to 2002, Singapore experienced an almost three-fold increase in breast cancer incidence. This increase appeared to be different across the three main ethnic groups: Chinese, Malays and Indians. This paper used age-period-cohort (APC) modelling, to determine the effects of age at diagnosis, calendar period, and birth cohort on breast cancer incidence for each ethnic group.

Methods: This study included all breast cancer cases (n = 15,269) in the three ethnic groups, reported to the Singapore Cancer Registry from 1968 to 2002 between the ages 25 to 79. Age-specific fertility rates from the Department of Statistics were used to explore the role of fertility.

Results: In the 1970s, Indian women had the highest age-standardized breast cancer but by the mid-1980s the highest rates were seen among the Chinese. Remarkable differences were seen in the age-specific incidence rates by ethnic groups. After age 49, the incidence rates for the Chinese and Malays leveled off whereas it continued to rise in the Indians. While our analyses provided some evidence that an age-drift model described the trend seen in the Indians, age-period-cohort model and age-cohort model had the best fit for the Chinese and Malays aged 25 to 79 respectively. Overall, Chinese and Malay women born in later cohorts were at increased risk of developing breast cancer relative to their counterparts in the earlier cohorts. The three ethnic groups experienced similar changes in their fertility in the 1970s, which likely explained much of the increase in their breast cancer incidence but not the ethnic differences. There was a stronger inverse association between total fertility rate and pre-menopausal breast cancer incidence in the Chinese and Malays than the Indians.

Conclusion: The observed dissimilarity among ethnic groups suggests ethnic differences in exposure or response to certain risk factors. It is likely that longer and subtler differences in childbearing trends and other risk factors may further explain these ethnic differences.

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Total fertility rates for Singaporean women aged 15 – 44 from 1968 – 2002, stratified by ethnicity. Source: Reports on Registration of Births and Deaths (1968 – 2002). (Note: Only number of live births in each year is included and female population denominators used are based on interpolation of census data in 1970, 1980, 1990 and 2000).
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Figure 4: Total fertility rates for Singaporean women aged 15 – 44 from 1968 – 2002, stratified by ethnicity. Source: Reports on Registration of Births and Deaths (1968 – 2002). (Note: Only number of live births in each year is included and female population denominators used are based on interpolation of census data in 1970, 1980, 1990 and 2000).

Mentions: Total fertility by calendar year declined across the three ethnic groups, from over 4,000 births per 1,000 women in the 1960s to around or less than 2,000 births per 1,000 women in the late 1990s (Figure 4). The Malays tend to have the highest total fertility rate, followed by the Indians and lastly the Chinese. There was also an increasing trend in the age at first birth for the three ethnic groups. The median age at first birth in 1970 ranged from 21.6 to 24.9, while in 2000, it ranged from 25.6 to 29.2 (Table 4). In 1970, the median age of first birth for Malay women was 21.6, compared to 24.9 for the Indians and 23.8 for the Chinese [17]. By the year 2000, the median age had increased to 25.6 for the Malays, 29.2 for the Indians and 28.9 for the Chinese. The Chinese had the highest rate of increase over the 30 years period while the Malays consistently had the median youngest age at first birth.


Ethnic differences in the time trend of female breast cancer incidence: Singapore, 1968-2002.

Sim X, Ali RA, Wedren S, Goh DL, Tan CS, Reilly M, Hall P, Chia KS - BMC Cancer (2006)

Total fertility rates for Singaporean women aged 15 – 44 from 1968 – 2002, stratified by ethnicity. Source: Reports on Registration of Births and Deaths (1968 – 2002). (Note: Only number of live births in each year is included and female population denominators used are based on interpolation of census data in 1970, 1980, 1990 and 2000).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1636657&req=5

Figure 4: Total fertility rates for Singaporean women aged 15 – 44 from 1968 – 2002, stratified by ethnicity. Source: Reports on Registration of Births and Deaths (1968 – 2002). (Note: Only number of live births in each year is included and female population denominators used are based on interpolation of census data in 1970, 1980, 1990 and 2000).
Mentions: Total fertility by calendar year declined across the three ethnic groups, from over 4,000 births per 1,000 women in the 1960s to around or less than 2,000 births per 1,000 women in the late 1990s (Figure 4). The Malays tend to have the highest total fertility rate, followed by the Indians and lastly the Chinese. There was also an increasing trend in the age at first birth for the three ethnic groups. The median age at first birth in 1970 ranged from 21.6 to 24.9, while in 2000, it ranged from 25.6 to 29.2 (Table 4). In 1970, the median age of first birth for Malay women was 21.6, compared to 24.9 for the Indians and 23.8 for the Chinese [17]. By the year 2000, the median age had increased to 25.6 for the Malays, 29.2 for the Indians and 28.9 for the Chinese. The Chinese had the highest rate of increase over the 30 years period while the Malays consistently had the median youngest age at first birth.

Bottom Line: While our analyses provided some evidence that an age-drift model described the trend seen in the Indians, age-period-cohort model and age-cohort model had the best fit for the Chinese and Malays aged 25 to 79 respectively.The observed dissimilarity among ethnic groups suggests ethnic differences in exposure or response to certain risk factors.It is likely that longer and subtler differences in childbearing trends and other risk factors may further explain these ethnic differences.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Molecular Epidemiology, National University of Singapore and Genome Institute of Singapore, Singapore. cmesx@nus.edu.sg <cmesx@nus.edu.sg>

ABSTRACT

Background: From 1968 to 2002, Singapore experienced an almost three-fold increase in breast cancer incidence. This increase appeared to be different across the three main ethnic groups: Chinese, Malays and Indians. This paper used age-period-cohort (APC) modelling, to determine the effects of age at diagnosis, calendar period, and birth cohort on breast cancer incidence for each ethnic group.

Methods: This study included all breast cancer cases (n = 15,269) in the three ethnic groups, reported to the Singapore Cancer Registry from 1968 to 2002 between the ages 25 to 79. Age-specific fertility rates from the Department of Statistics were used to explore the role of fertility.

Results: In the 1970s, Indian women had the highest age-standardized breast cancer but by the mid-1980s the highest rates were seen among the Chinese. Remarkable differences were seen in the age-specific incidence rates by ethnic groups. After age 49, the incidence rates for the Chinese and Malays leveled off whereas it continued to rise in the Indians. While our analyses provided some evidence that an age-drift model described the trend seen in the Indians, age-period-cohort model and age-cohort model had the best fit for the Chinese and Malays aged 25 to 79 respectively. Overall, Chinese and Malay women born in later cohorts were at increased risk of developing breast cancer relative to their counterparts in the earlier cohorts. The three ethnic groups experienced similar changes in their fertility in the 1970s, which likely explained much of the increase in their breast cancer incidence but not the ethnic differences. There was a stronger inverse association between total fertility rate and pre-menopausal breast cancer incidence in the Chinese and Malays than the Indians.

Conclusion: The observed dissimilarity among ethnic groups suggests ethnic differences in exposure or response to certain risk factors. It is likely that longer and subtler differences in childbearing trends and other risk factors may further explain these ethnic differences.

Show MeSH
Related in: MedlinePlus