Killer on the tral

Migrating to another country may lower or raise chances of contracting breast cancer, reveals a new study

By Padma Rao
Published: Tuesday 31 October 1995

A RECENT study carried in the Journal of the us National Cancer Institute in Bethesda says that migrating to a country with a high breast cancer incidence may enhance the risk of dying from the killer disease for immigrant women from traditionally low-risk countries.

Enrich V Yliewer of the Australian National University, Canberra, Australia, and Ken R Smith of the University of Utaj in Salt Lake City, reveals that changes in diet, air, water, and stress altered reproductive habits and lifestyle. It may cause breast cancer death rates to spiral among immigrant women living in high-risk countries like Australia and Canada. The report also examines Indian and Pakistani women.

The study provides startling insights: environmental and lifestyle factors associated with the new residence, influence breast cancer rate among immigrants in a way that their mortality risk either rises or falls (depending on where they came from), to the level prevalent among the women of the adopted country.

Breast cancer death rates among immigrants to Australia and Canada rose (or fell, as the case was) to match that of their local counterparts within 30 years - or less - of migration to those countries. Although the authors warn that no precise conclusion can be drawn on the high-risk to low-risk residence movement due to the lack of relevant data, their research revealed that convergence - as the phenomenon of the merger of death rates is referred to was a constant.

Referring to previous studies on usbased Asian immigrants, the report showed how the risk of contracting breast cancer increased with the period of residence upto 8- 14 years. The overall picture that emerges is that Asian immigrants in Australia and Canada have an increased risk of contracting the deadly tumour. Earlier, the most consistently found risk factors responsible for the vast variance in the incidence of breast cancer all over the world were stated to be reproductive factors - including hormonal levels and diet. But the new study shows that migration is likely to affect these aspects, too.

Immigrant women may delay their first childbirth, or childbearing as a whole for economic, professional or other reasons. Therefore, immigrant women may have fewer children than their sisters in their own country. This directly affects fertility rates and the average number of children born to immigrants. The shift in fertility rates was found to be consistent with the convergence in breast cancer mortality rates.

Also, an examination of 5 Hawaiian ethnic groups showed that there was a clear relationship between total fat intake per day and breast cancer incidence rates. A previous us analysis quoted by the report had revealed that there was increase in breast cancer among us-based Japanese women - comfortably explained by an increase in fat consumption.

Interestingly, the most important aspect of the new report is that it rein- forces notions already held by many specialists, that the risk of breast cancer is not necessarily something certain women are born with, but rather, some- thing which can be influenced by individual experience.

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