Breast cancer epidemiology - Incidence & mortality

Module introduction
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Estimated 2005 New Cancer Cases & Deaths by Primary Site for U.S. Females
Incidence		Mortality
Primary site*	Cases	Primary site*	Cases
Breast	211,240	Lung & bronchus	73,020
Lung & bronchus	79,560	Breast	40,410
Colon & rectum	73,470	Colon & rectum	27,750
Uterine corpus	40,880	Ovary	16,210
Non-Hodgkin lymphoma	27,320	Pancreas	15,980
Ovary	22,220
Cervix**	10,370	Cervix**	3,710
* Skin cancers and in situ cancers are not included in these data ** Cervical cancer data included for comparison, but are not in rank order (ACS, 2005; based on data from NCI Surveillance, Epidemiology, and End Results program SEER, and National Center for Health Statistics)

Incidence

Breast cancer is the most common type of cancer diagnosed in women, excluding skin cancer (ACS, 2005).

Almost one third (32%) of all cancers diagnosed in women are breast cancer (ACS, 2004f).
However, the incidence of breast cancer (number of new breast cancers per 100,000 women) varies by race and ethnicity. American Indian and Native Alaskan women have the lowest incidence whereas White women have the highest incidence of breast cancer diagnoses (ACS, 2005).

The incidence of breast cancer has increased over the past four decades.

The incidence increased rapidly in the 1980s, associated with increased use of mammography, and the incidence increased more gradually in the 1990s (ACS, 2004f; ACS, 2005).
The increase since 1990 is mainly in women 50 and older, consistent with the two primary risk factors for breast cancer: increasing age and female gender.
The continued increase in incidence of breast cancer is associated with

increased mammography screening
an increased use of hormone replacement therapy
an increase in obesity in postmenopausal women
lower levels of physical activity
earlier menarche, delayed childbearing, and having fewer children (ACS, 2004f)

The increased incidence of ductal carcinoma in situ (DCIS, a non-invasive lesion in the duct system considered by some to be a pre-cancer) is directly associated with the increased use of mammography and the detection of lesions before they can be felt (Jemal et al., 2005).

Mortality

Cancer has become the leading cause of death among U.S. women aged 40 to 79 (Jemal et al., 2005).

Breast cancer is the leading cause of cancer death among women aged 20 to 59 years.
Lung/bronchial cancer is the leading cancer death among women 60 years and older.

However, mortality rates from breast cancer in the U.S. have decreased significantly from 33.1 per 100,000 women in 1990 to 26.7 per 100,000 women in 2000 (Stewart et al., 2004).

The largest decreases in mortality have been among women under 50 years old (ACS, 2005).
Considered on an annual basis, the mortality rates from breast cancer have declined by 2.3% per year between 1990 and 2001 (ACS, 2005).
The decline in breast cancer mortality rates was only 0.9% for African American women while the decline was 2.1% for non-Hispanic White women (Stewart et al., 2004).
African American women have the highest mortality rates whereas Asian American and Pacific Islander women have the lowest mortality rates from breast cancer (ACS, 2005).

table of breast cancer incidence and mortality rates by race/ethnicity

The decline in breast cancer mortality rates is associated with a number of factors:

increased awareness of breast cancer
earlier detection of breast cancer through increased screening
improved treatment (ACS, 2005)

cancer incidence and mortality for Wisconsin females by site

Breast cancer rates among men

Although outside the scope of this project, it is important for clinicians to be aware that men are at risk for breast cancer as well. An estimated 1,690 men in the U.S. will be diagnosed with breast cancer and an estimated 460 men will die from breast cancer in 2005 (ACS, 2005). Approximately 1% of the new cases of breast cancer diagnosed in Wisconsin are in men; 42 men were diagnosed with breast cancer in 2001 (Wisconsin Cancer Reporting System, 2004). An estimated 35 men are diagnosed with breast cancer each year in Wisconsin (ACS, 2004b). Data were not available for mortality rates for men with breast cancer in Wisconsin.

Introduction, incidence & mortality