The National Cancer Institute (NCI) recently announced that the breast cancer death rate in American women continued to decline through 1993. This finding suggests, says NCI, that improved breast cancer management, from early detection to treatment, is having a beneficial effect.
Breast cancer mortality trends for US white women have improved markedly in the 1990s compared with the 1980s. For black women, increases in mortality persist, especially among older women, but the overall increase has slowed significantly.
During the most recent 5-year period of available data, 1989 to 1993, age-adjusted breast cancer mortality fell approximately 6% in white women and rose about 1% in black women. By comparison, from 1980 to 1989, rates increased 3% in white women and 16% in black women, according to data from the National Center for Health Statistics.
"These findings are good news, but not good enough," said US Department of Health and Human Services (HHS) Secretary Donna E. Shalala.
"The data suggest the trend is starting to move in a positive direction for African-American women as well as white women. Rates have declined among younger black women, although they are still higher than those of white women and are improving more slowly," NCI Director Richard Klausner, MD, said.
The overall death rate from breast cancer in US women has fallen about 5% in recent years, dropping from 27.5 per 100,000 women in 1989 to 25.9 per 100, 000 in 1993. This year, an estimated 44,300 women will die of the disease nationwide, but that estimate could prove to be too high if the trend continues.
In both white and black women, the greatest improvements in mortality during the recent 5-year period were seen in younger age groups, but the changes were more modest in blacks than in whites of all ages. Other mortality trends were also seen:
- Among white women, death rates declined for all decades of age from 30 to 79 years.
- Among black women, rates were down for all decades from 30 to 69 years.
- For women age 30 to 39 years, rates dropped about 13% in whites and 5% in blacks.
- For women age 40 to 49 years, rates dropped 9% in whites and 2% in blacks.
- For women age 50 to 59 years, rates declined 9% in whites and less than 1% in blacks.
- For women 60 to 69 years old, rates decreased 6% in whites and less than 1% in blacks.
- For women 70 to 79 years old, rates increased 5% in blacks and decreased 3% in whites.
- For women 80 years and older, rates increased 5% in blacks and 2% in whites.
The median age at death is 68 years for white breast cancer patients and 62 years for black breast cancer patients.
Earlier Detection, Improved Treatment
Experts believe the recent decline in breast cancer mortality is partly a result of mammography screening, which rapidly increased in the United States during the 1980s and resulted in a shift toward the detection of breast cancer at earlier, more curable stages. But they say screening cannot explain all of the decline.
"Such changes in mortality trends across a wide age range usually indicate improvements in medical interventions, and examination of stage-specific breast cancer incidence rates and survival rates suggests that both earlier detection and improved treatment are likely contributing to the recent declines in breast cancer mortality," said Robert Tarone, PhD, of the NCI's Biostatistics Branch.
"Further study is required to determine the relative contribution of early detection and improved treatment to the recent declines in breast cancer mortality," added Brenda K. Edwards, PhD, director of NCI's Cancer Control Research Program. "Research is now under way to investigate the impact of adjuvant therapy on mortality rates."
Health authorities in the United Kingdom have also reported a steep decline in the breast cancer death rate among women age 55 to 69 during roughly the same time period. Mortality in this group dropped 12% from 1987 to 1994. This trend began at the same time as the introduction of the UK breast screening program, but researchers there have concluded that it occurred too soon to be entirely a result of screening. Instead, they attribute much of the decline to more effective treatment, particularly the widespread adoption of tamoxifen(Drug information on tamoxifen) (Nolvadex) therapy. These results add weight to the evidence for a similar beneficial effect of treatment advances on breast cancer mortality in US women according to the NCI statement.
Racial/Ethnic Differences in Mortality
Breast cancer death rates vary fairly widely among racial and ethnic groups in the United States. Hispanic, Chinese, Filipino, and Japanese women have annual rates at or below 15 per 100,000 population, while black, white, and Native Hawaiian women have rates above 25 per 100,000.
Edwards said the racial differences in mortality depend on several factors, including the risk of developing breast cancer, access to screening, and early detection, treatment and medical follow-up, and supportive care. The NCI is investigating differential risk factors, pattern of care, and clinical and biologic prognostic factors for survival, she said, adding that "understanding of these relationships is still incomplete."
The continued rise in breast cancer mortality in older women extends a long-standing, trend of increasing breast cancer risk for women born from 1900 to 1920, Tarone said. Researchers believe the increasing mortality in this group reflects changes in various risk factors, such as delayed childbearing early in the century.
Less well-understood is the declining mortality among women under age 40, who generally are not screened. The trend in this group appears to reflect a recent change in risk factors above and beyond the improvements due to medical intervention.
HHS-Sponsored Research Programs
HHS support for breast cancer research, prevention, and treatment has increased from $271 million in 1993 to $476 million in 1996. Special programs include:
- a comprehensive effort by the NCI to identify the genetic and biologic basis of breast cancer, characterize patterns of risk in the population, and apply the knowledge gained through basic research to more effective prevention and treatment strategies;
- the CDC's National Breast and Cervical Cancer Early Detection program, which offers free or low-cost mammography to uninsured or low-income women;
- the FDA's quality standards for mammography services; and
- the clinical practice guidelines on mammography issued by the Agency for Health Care Policy and Research.
In addition, the Health Care Financing Administration of the HHS helps pay for mammography for beneficiaries of the Medicare program. In recent years, some 37% of women beneficiaries have been making use of Medicare's mammography coverage. An ongoing HHS campaign, targeted especially at women over age 65, aims to increase the use of the benefit to at least 60% by the year 2000.