Breast cancer trends in Indian residents and emigrants portend an emerging epidemic for India.

PURPOSE: As developing nations such as India become increasingly Westernized, incidence rates will increase for many cancers. Presently, breast cancer is the leading cancer site in female residents of India, but rates are considerably lower than in Western countries. Trends observed in Indian immigrants to the West may help predict changes expected in India. METHODS: Data were obtained from Indian cancer registries, the SEER program in the USA, IARC scientific database, and published studies. Incidence, age at diagnosis, stage at diagnosis, and hormone receptor status in these three populations were compared for the period 1993-1999. RESULTS: Age-adjusted (to world standard population) incidence rates (per 100,000) in Indian immigrants (47.0-61.0) were higher than in Indian residents (7.2-33.4) but lower than in Western whites (83.1-112.0). Compared to Indian residents, Indian immigrant cases tended to be older (49 years +), diagnosed at an earlier stage, and more often hormone receptor positive, sharing similarities with Western white women. CONCLUSIONS: The intermediate breast cancer trends exhibited by Indian immigrants may help predict future incidence trends amongst Indian (particularly urban) residents, which have major public health implications for India as urbanization and Westernization continue. We suggest adding demographic variables to cancer registry data, and additional studies on immigrant Indian populations.

Stage at diagnosis and relative differences in breast and prostate cancer incidence in India: comparison with the United States.

PURPOSE: To examine and reconcile differences in incidence rates and stage-at-initial-presentation of prostate and breast cancers in India, a country in epidemiologic transition. METHODS: Age-adjusted prostate and female breast cancer incidence rates and proportion of cases by stage-at-diagnosis were compared. Data were derived from the National Cancer Registry Program of India, other Indian registries, the International Agency for Research on Cancer, and the US/ NCI Surveillance, Epidemiology, and End Results (SEER) Program. RESULTS: Average annual cancer incidence rates in India ranged from 5.0 to 9.1 per 100,000/year for prostate and 7.2 to 31.3 per 100,000/year for female breast. Comparative rates in the US for prostate cancer are 110.4 for Whites and 180.9 for Blacks; for female breast, the rates are 86.6 for Blacks and 96.4 for Whites. Notable differences were observed between rural and urban areas in India, while such differences by rurality appear to be much smaller in the US. Overall, about 50-55% of breast cancer cases and about 85% of prostate cancers were detected at late (III and IV) stage; in contrast to the US where 15% of either cancer is diagnosed at late stage. CONCLUSIONS: Differences in stage-at-diagnosis help explain variations in incidence rates among cancer registries in India and rate differences between India and the US. These findings indicate that erroneous inferences will result from incidence-rate comparisons that do not take into account stage-at-diagnosis. Results also point to epidemiologic studies that could be conducted to deepen understanding of the etiology of these cancers. By enhancing data on staging, the Indian cancer registries could widen the scope of collaborative, cross-national research.