Breast Cancer Incidence and Mortality--United States, 1992

Breast cancer is the most commonly diagnosed nondermatologic cancerand the second leading cause of cancer-related deaths among womenin the United States. In 1996, a total of 184,300 new cases ofand 44,300 deaths from invasive breast cancer are projected amongwomen. To assess trends in incidence and death rates for breastcancer among US women, the CDC analyzed national incidence datafrom the National Cancer Institute's Surveillance, Epidemiology,and End Results (SEER) program and death-certificate data fromthe CDC's National Center for Health Statistics (NCHS).

This report presents incidence and death rates for breast cancerfor 1992 (the most recent year for which SEER data were available)and summarizes trends in these rates for 1973 to 1992. Overall,these findings indicate that incidence rates for invasive breastcancer increased among women during 1973 to 1987 and stabilizedduring 1988 to 1992, while mortality remained stable during 1973to 1988 and decreased during 1989 to 1992.

The incidence rate of breast cancer in the United States is estimatedby using aggregate data reported by the SEER program, which includesa nonrandom sample of approximately 14% of the US population.Based on 1990 data from the Bureau of the Census, the demographiccharacteristics of persons included in SEER is representativeof the total US population for whites and blacks; in addition,persons included in SEER reflect the percentage of persons amongthe total US population living below the poverty level* and thepercentage of adults who graduated from high school. However,a higher proportion of persons included in SEER resided in urbanareas.

This analysis includes all cases of invasive breast cancer (InternationalClassification of Diseases, for Oncology, codes C50.0-C50.9) registeredin SEER. Annual incidence rates were computed for 1973 to 1992,and race- and age-specific average annual incidence rates werecomputed for the combined years of 1988 to 1992.

Decedents for which the underlying cause of death was breast cancer(International Classification of Diseases, Adapted, Ninth Revision,codes 174.0-174.9) were identified from public-use mortality datatapes. Annual death rates were computed for 1973 to 1992, andrace-specific average annual death rates by age and by state werecomputed for the combined years of 1988 to 1992.

Denominators for annual incidence and death rate calculationswere derived from US census population estimates. Rates were directlystandardized to the age distribution of the 1970 US populationusing 5-year age groupings. Data are presented only for whitesand blacks because numbers for other racial/ethnic groups weretoo small for meaningful analysis.

Breast Cancer Incidence

In 1992, the overall age-adjusted incidence rate for breast cancerwas 110.6 per 100,000 women. The rate for white women (113.1)was higher than that for black women (101.0).

During 1973 to 1992, the overall incidence rate increased from82.5 to 110.6: rates increased steadily during 1973 to 1987 andstabilized during 1988 to 1992 (Figure 1). During 1988 to 1992,incidence rates increased directly with age until age 75 to 79years for whites and age 80 to 84 years for blacks; the ratesfor whites and blacks were similar for women age less than 45years, but for women age 45 years or more, the rate was higherfor whites than for blacks. During 1973 to 1992, race-specificrates varied: for white women, the age-adjusted rate increased34% (from 84.3 to 113.1) and, for black women, increased 47% (from68.7 to 101.0).

Breast Cancer Mortality

In 1992, a total of 43,063 US women died from breast cancer. Thedeath rate was 26.2 per 100,000 women.

During 1973 to 1992, the overall death rate varied; rates werestable during 1973 to 1988, before decreasing during 1989 to 1992(Figure 1). During 1988 to 1992, the overall ratio of black-to-whitedeath rates was 1.2. Rates increased directly with age. For womenage less than 70 years, the rate was higher for blacks than forwhites; for women age 70 years or more, the rate was higher forwhites than for blacks. During this period, race-specific ratesvaried. During 1989 to 1992, the rate for white women decreased6% (from 27.5 to 26.0) and, for black women, increased 3% (from30.4 to 31.2).

During 1988 to 1992, the state-specific age-adjusted death rateranged from 18.2 in Hawaii to 35.3 in the District of Columbia.

Editorial Note from the CDC

The findings in this report indicate that incidence rates forbreast cancer increased 34% during 1973 to 1992. The increaseand later stabilization of incidence rates during the 1980s ismost likely related to increased use of breast cancer screeningmethods, particularly mammography and clinical breast examination,which enable earlier diagnosis of the disease.

The decrease in breast cancer death rates during 1989 to 1992may reflect a combination of factors, including earlier diagnosisand improved treatment. For example, screening mammography andclinical breast examination are effective methods for reducingbreast cancer mortality among women age 50 years or more. Survivalfrom breast cancer increases when the disease is diagnosed atearlier stages, and from 1974-1976 to 1986-1991, the survivalrate for invasive breast cancer increased substantially.

Differences in the race-specific and state-specific incidenceand death rates for breast cancer during 1973 to 1992 may reflectdifferences in such factors as socioeconomic status, access toand delivery of medical care, and the prevalence of specific risksfor disease. For example, women in minority populations are lesslikely than white women to be screened for breast cancer. Althoughsocioeconomic and risk-factor data were not analyzed in this report,the findings underscore the need for further characterizationof the burden of cancer for US women in racial/ethnic, geographic,and other subgroups.

Early detection and appropriate treatment are essential to reducingthe burden of breast cancer in the United States. The CDC's NationalBreast and Cervical Cancer Early Detection Program provides earlydetection screening and referral services for cancers of the breastand cervix among older women who have low incomes or are uninsured,underinsured, or in a racial/ethnic minority. Additional effortsby this program and health-care professionals are needed to ensurethat every US woman at risk for breast cancer receives breastcancer screening, prompt follow-up, and assurance that tests areconducted in accordance with current federal quality standards.

Adapted from Morbidity and Mortality Weekly Report, vol 45, no.39, October 4, 1996.