Cancer Incidence in British Indians
Cancer incidence rates are lower in India than in Britain. Studies in migrant populations can help explain the relative contribution of genetic and environmental factors in cancer. Leicester has the largest population of Indian origin in Britain with the first migrants arriving in the 1950s. Studies of cancer incidence in British Asians using self-assigned ethnicity have been hampered by the incomplete ethnicity data held by cancer registries. Since 1996, self-assigned ethnicity has been recorded in the Hospital Episodes Statistics (HES) database and is almost complete in Leicester.
To compare cancer incidence in British Indians and British Whites using ethnicity data from the Hospital Episodes Statistics (HES) database.
- Trent Cancer Registry provided us with data on all cancer registrations from January 2001 to December 2006 for residents of the local authority of Leicester.
- The registry data consisted of individual patient records with information on sex, age, site of the cancer and deprivation.
- Ethnicity for each person with cancer was then obtained by linkage to the HES database and was available for 93% of cancer registrations (6178 / 6615). The name recognition software ‘Nam- Pehchan’ was then used for those with a missing ethnicity code showing that 5% or fewer were likely to be of South Asian origin.
- Population estimates for the local authority of Leicester were obtained from the 2001 census, stratified by sex, age, ethnicity, and quintile of deprivation.
- Age-standardised rates per 100,000 person-years were calculated for British Indians and British Whites.
- Poisson regression was used to estimate incident rate ratios (IRRs) in British Indians compared to British Whites, adjusted for age and deprivation.
- In 2001 - 2006, there were 714 cancers registered among British Indians and 4609 among British whites in Leicester.
- British Indians had lower age-standardised rates than British Whites for all cancers, and cancer of the prostate, lung, colorectum and breast. (Figure 1.)
Figure 1: Age standardised cancer incidence rates for British Indians compared to British Whites living in Leicester.
Incident rate ratios (I95% confidence intervals) in British Indians compared to British Whites living in Leicester, adjusted for age and deprivation.
|All cancers||0.59 (0.52 – 0.66)||0.64 (0.58 - 0.72)|
|Lung||0.39 (0.28 – 0.54)||0.15 (0.08 – 0.27)|
|Colorectum||0.59 (0.42 – 0.84)||0.61 (0.42 - 0.89)|
|Head and neck||0.82 (0.53 – 1.27)||1.63 (0.89 – 3.00)|
|Breast||-||0.69 (0.57 – 0.83)|
|Prostate||0.73 (0.56 – 0.96)||-|
Conclusions and future plans
- This is the first study to estimate cancer incidence rates in British Indians using self–assigned ethnicity.
- It confirms results of studies based on name analysis, showing that the incidence of certain cancers in British Indians is lower than in British Whites.
- Further research is planned to investigate how cancer incidence varies by duration of residence, age at migration, and between first and second generation migrants.
- Further studies investigating the role of diet in explaining the lower incidence of colorectal cancer in Indians are also planned with a case-control study looking at the association of life-long vegetarianism and colorectal cancer in India already underway.