A snapshot of breast cancer worldwide

by Laura Shea, R.N., Prevention First Coalition

This report is a summary of a presentation by Dr. Annie Sasco of the International Agency of Research on Cancer (IARC) of the World Health Organization. This was part of the opening plenary session entitled, “A Look at Breast Cancer in the 21st Century.”¹ It is intended as a snapshot of the global picture. References are provided for those who wish to access statistics not discussed in her presentation.

We have good reason to be worried about cancer in general, and breast cancer in particular in the 21st century. Currently, worldwide, 11 million cancer cases are diagnosed each year—5.7 million in women, 5.3 million in men. An estimated 22 million people are living with cancer while more than 6 million people die of it each year—2.7 million women and 3.5 million men.

More than a million women are diagnosed with breast cancer each year, contributing to an estimated 4 million women living with breast cancer, and 400,000 dying of the disease each year. Breast cancer is by far the most common cancer in women worldwide; cervical cancer is second with nearly half a million new cases each year. (Dr. Sasco pointed out that although breast cancer has been more prevalent for many years in the industrialized world, this is now also the case in developing countries.)

Breast cancer remains a relatively rare disease among young women under 30 with only “a few cases“each year. Most cases occur in the decade after the age of 50.² Between the years 1980 and 2000, the number of cases of breast cancer almost doubled, an increase that cannot be explained by an increase in population. According to Dr. Sasco, improved detection technologies can account for some of this increase, but not all. The good news is that, with newer treatments, more women are surviving breast cancer today as compared to 20 years ago and, in richer countries such as the U.K. and U.S.A. where women are more likely to have access to health care, mortality rates are declining.³

Geographically, the incidence of cancer in general is highest in North America, Australia, New Zealand and parts of Europe. The ten countries with the highest rates of breast cancer are in North America and Europe, although some South American countries—notably Argentina and Uruguay—also have high rates. (In Canada, there are over 19,000 new breast cancer cases each year and close to 5,600 deaths.) The incidence is lower in Eastern European countries and lowest in Asia and Africa.

“How can we explain these differences?“asked Dr. Sasco, “Is it because women in Laos or Haiti are genetically different from women in Canada and France? Or is it because life style and environment are different?“Some studies of migrants who moved from China to Chinatown in San Francisco or Los Angeles show that it is not the genetic background but the change of country that matters. “Either you, or more likely your daughters and granddaughters, will—little by little—catch up to the disease rate of the country you immigrate to.”

The “traditional” risk factors associated with breast cancer are genetics, reproductive history, and life style. Genetic factors represent less than 10% of all breast cancer cases so they cannot explain why the majority of breast cancers occur. Dr. Sasco confirmed that a woman“s reproductive history plays a role in slightly increasing her risk of breast cancer, as do life style issues such as high fat diet, obesity (at least after menopause), and lack of physical exercise. But these latter risk factors are best explained by their impact on women“s hormones.

However, only a small proportion of breast cancer cases can be explained by the traditional risk factors: “We still do not know why we see increases in breast cancer in many countries of the world. Most probably, the hormonal pathway is the clue to breast cancer but there are many determinants and we need more data because if age at menarche (first menstrual period) is a risk factor, then we have to find out why girls in the world are getting their first period earlier than their mothers and grandmothers did.”

Dr. Sasco believes that preventative strategies that seek to identify environmental links to breast cancer are embedded in the Precautionary Principle which, simply put, advises to “first, do no harm.”4 “We know that some compounds of chemical agents are recognized carcinogens5; we know that some things—including radiation, some specific carcinogens and hormones—increase the risk of cancer, including breast cancer.” We need more research on the impact of environmental toxins on human health. Studies need to be done on both the effects of specific compounds, as well as the cumulative impact of exposure to low doses of various compounds. Dr. Sasco concluded by stressing how crucial it is to avoid exposure to compounds we know or suspect to be harmful. This is particularly important during fetal development, and around the ages of puberty and menopause, periods of change when women“s bodies are extremely sensitive to hormone activity.

I tend to hold my breath when scientists start talking about individual “risk factors” dreading the thought of hearing, once again, that my state of health is entirely my responsibility. I was pleasantly surprised to hear Dr. Sasco say that although there are some things we can do to help reduce our individual risk of getting diseases like breast cancer, our health is also “in the hands of politicians“who need to “set up [environmental] regulations [because] we cannot control the air we breathe or the water we drink.” Our health is indeed a political issue.

References:

From the World Conference on Breast Cancer, Victoria, BC, 2002. The audio tape is available in the BCAM library.

For more statistics on age trends in Canada and Canadian breast cancer statistics in general, see The Canadian Cancer Society“s website at: www.cancer.ca

The Canadian Breast Cancer Research Initiative Biennial Report 1999-2000. Available in the BCAM library or visit: www.breast.cancer.ca/english/e_frame.htm (Click on “statistics”) Note: invalid link

For more information on the Precautionary Principle, see: www.sehn.org

The International Agency for Research on Cancer: http://www.iarc.fr/ Click on Research Units then on Carcinogen Identification and Evaluation