Cancer incidence in the south Asian population of California, 1988-2000

Abstract

Background: Although South Asians (SA) form a large majority of the Asian population of U.S., very little is known about cancer in this immigrant population. SAs comprise people having origins mainly in India, Pakistan, Bangladesh and Sri Lanka. We calculated age-adjusted incidence and time trends of cancer in the SA population of California (state with the largest concentration of SAs) between 1988-2000 and compared these rates to rates in native Asian Indians as well as to those experienced by the Asian/Pacific Islander (API) and White, non-Hispanic population (NHW) population of California.

Methods: Age adjusted incidence rates observed among the SA population of California during the time period 1988-2000 were calculated. To correctly identify the ethnicity of cancer cases, 'Nam Pehchan' (British developed software) was used to identify numerator cases of SA origin from the population-based cancer registry in California (CCR). Denominators were obtained from the U.S. Census Bureau. Incidence rates in SAs were calculated and a time trend analysis was also performed. Comparison data on the API and the NHW population of California were also obtained from CCR and rates from Globocan 2002 were used to determine rates in India.

Results: Between 1988-2000, 5192 cancers were diagnosed in SAs of California. Compared to rates in native Asian Indians, rates of cancer in SAs in California were higher for all sites except oropharyngeal, oesophageal and cervical cancers. Compared to APIs of California, SA population experienced more cancers of oesophagus, gall bladder, prostate, breast, ovary and uterus, as well as lymphomas, leukemias and multiple myelomas. Compared to NHW population of California, SAs experienced more cancers of the stomach, liver and bile duct, gall bladder, cervix and multiple myelomas. Significantly increasing time trends were observed in colon and breast cancer incidence.

Conclusion: SA population of California experiences unique patterns of cancer incidence most likely associated with acculturation, screening and tobacco habits. There is need for early diagnosis of leading cancers in SA. If necessary steps are not taken to curb the growth of breast, colon and lung cancer, rates in SA will soon approximate those of the NHW population of California.

Figure 1

Comparison of invasive cancers, all sites combined, in the SA¹, NHW² and API³ population of California, 1988–2000. * Rates are per 100,000 and age-adjusted to the U.S. 2000 standard population (18 age groups). ¹ south Asian. ² White, non-Hispanic. ³ Asian/Pacific Islanders.

Figure 2

Top five leading cancers with trends in California south Asian males, 1988–2000. * Rates are per 100,000 and age-adjusted to the U.S. 2000 standard population (18 age groups).

Figure 3

Top five leading cancers with trends in California south Asian females, 1988–2000. * Rates are per 100,000 and age-adjusted to the U.S. 2000 standard population (18 age groups).