Breast Cancer Facts, 2008

Breast Cancer Statistics

Breast cancer now strikes more women in the world than any other type of cancer except skin cancer. In the United States, a woman’s lifetime risk of breast cancer increased steadily and dramatically from the 1930s, when the first reliable cancer incidence records (starting in the state of Connecticut) were established, through the end of the 20th century. Between 1973 and 1998, breast cancer incidence in the United States increased by more than 40 percent. Today, a woman’s lifetime risk of breast cancer is one in eight.

The incidence of breast cancer varies considerably by a number of factors, including age and ethnicity. In the U.S. between 2000 and 2004, white women had the highest overall annual incidence rate for the disease (132.5 cases per 100,000 women), followed by African American (118.3 per 100,000), Hispanic (89.3 per 100,000), Asian American/Pacific Islander (89.0 per 100,000) and American Indian/Alaska Native (69.8 per 100,000) women.

The great majority of women diagnosed with breast cancer are 45 years of age or older, and a higher rate of the disease is found for white women as compared to African American women for all ages older than 45. Nevertheless, there is a higher incidence rate for African American than white women for ages 35 years and younger. Most importantly, younger women in general, and younger African American women in particular, present with forms of the disease that are more aggressive and more difficult to treat effectively. See Breast Cancer Incidence and Mortality by Race and Ethnicity for more information.

Globally, more than 1.15 million women were diagnosed with breast cancer in 2002. The highest rates are found in the industrialized nations of North America and western Europe, while lower rates are generally found in western Asia, southern Africa and South America, although even in these areas cancer of the breast is the most commonly diagnosed cancer in women. In northern Africa, as in many countries that are either developing or in transition, breast cancer rates are escalating sharply. While some of the changes in rates may be associated with improved ability to detect the disease along with changes in lifestyle and reproductive histories, migration studies suggest that much of the variability in international incidence rates might be environmentally related.

Breast Cancer Rates Are Falling?

Recent data indicate a significant decrease in breast cancer incidence in the United States. These data are cause for excitement, the first indications in decades that the sum of factors leading to the development of breast cancer may be receding. Most notably, several reports in the recent scientific literature have associated these decreases in (ER+, post-menopausal) breast cancer rates to very recent decreases in use of post-menopausal hormone replacement therapy (HRT).

There could be other factors contributing to this decline. It has been three decades since many pesticides, including DDT, have been banned. Although we all carry remnants of DDT’s earlier large-scale usage, concentrated exposures during critical periods of breast development are much lower than they were for young girls several decades ago.

Similarly, federal and state regulations have succeeded in removing from common use several other chemicals that have been implicated in the rising risk for breast cancer. For example, our air is generally cleaner than it was 35 years ago, reducing exposure to PAHs and other air pollutants linked to breast cancer. And smoking restrictions in workplaces and public spaces have greatly reduced our exposures to secondhand smoke, a factor that is especially important for young children and adolescents.

As always, patterns of disease incidence, including breast cancer, need to be watched for the short term and the longer term. Still, declines in breast cancer rates provide real promise for the future that by decreasing exposures to exogenous estrogens, estrogen mimics, endocrine disruptors and other carcinogens, we may continue to lower the levels of breast cancer and eventually prevent the disease in the future.

Breast Cancer is Life-Threatening

Looking at national mortality data and aggregating across all possibly affected organs, cancer is the leading cause of death for U.S. women between the ages of 40 and 79, and the second most prevalent cause of death for all other ages. Cancer of the breast results in the highest mortality rates of any cancers in women between the ages of 20 and 59 years. Although rates of mortality from breast cancer remain high for older women, the elderly are more likely to succumb to lung cancer than breast cancer.

The Environmental Links to Breast Cancer

All women are at risk for breast cancer, regardless of hereditary factors. In fact, no more than 10 percent of people with breast cancer have a genetic predisposition to the disease. Other known risk factors and personal characteristics include personal or family history of breast cancer, high breast tissue density, earlier onset of menstruation (12 years or younger), later menopause (55 years or older), late first-term pregnancy (30 years or older), no children or no breast-feeding, early or recent use of oral contraceptives, more than four years use of hormone replacement therapy, postmenopausal obesity, alcohol consumption, exposures to secondhand cigarette smoke and exposure to ionizing radiation.

Although environmental exposures are not generally cited as risk factors for the disease (except for diet, pharmaceuticals and radiation), a substantial body of evidence indicates that exposures to certain toxic chemicals and hormone-mimicking compounds contribute to the development of breast cancer.

Detection Is Not Prevention

Mammography does not prevent breast cancer, but the earlier breast cancer is detected by self-exam or mammography and followed by appropriate treatment, the greater the chance of survival. However, mammograms fail to detect as much as 20 percent of breast cancer in women over 50, and as much as 40 percent in younger women.

Mammography is not early detection. By the time a tumor can be spotted on a mammogram, it has been growing, on average, eight to 10 years. In addition, mammography involves exposure to radiation, a known carcinogen.

For references, see State of the Evidence 2008.