Trends in Breast Cancer Incidence and Outcomes in the US: An Update from the American Cancer Society
The most recent statistics about breast cancer in the US reflect significant changes in disease detection, treatment and distribution of resources from state to state. There are differences among ethnicities that are just beginning to be learned, and more observation is needed to equalize outcomes for all women.
Breast Cancer Statistics, 2017, Racial Disparity in Mortality by State
Authors: DeSantis, CE et al.
Source: CA: A CA J Clin 2017;000:000-000 doi 10.3322/caac.21412
Every two years, the American Cancer Society evaluates the latest trends in breast cancer incidence, mortality, survival and screening by race/ethnicity in the US. This recent report provides the latest data about breast cancer outcomes among ethnic groups from 2004-2017. Data for non-Hispanic white (NHW), non-Hispanic Black (NHB), Hispanic, Asian/Pacific Islander (API) and American Indian/Alaska Native (AI/AN) women was collected and reviewed. The data for AI/AN women was not consistently available.
Approximately 252,710 new cases of invasive breast cancer are expected in 2017. About 63,410 cases of in situ disease are expected. The majority (81%) of cases will occur in women over age 50. The lifetime risk of breast cancer in the US is 1 in 8, or 12.4%. The median age at diagnosis for all women is 62 years, but the age is younger for black women (59).
Breast cancer incidence rose rapidly in the 1980s and 1990s, in large part because of the use of screening mammography. Once the statistical effects of early detection stabilized, the incidence of breast cancer remained relatively constant for a few years. Towards the late 1990s, the rate rose again, mostly among older women. This was believed to be due to rising rates of obesity as well as the use of hormone replacement therapy (HRT). Rates began to drop around the year 2000, likely because of the drop in the use of HRT and also because of decreased rates of screening mammography over time (70% in 2000 and 64% in 2015).
Looking at breast cancer incidence among women aged 50 or older, the rates are highest among NHW women, followed by NHB women, Hispanic women and API women. The rates drop with advancing age in each group.
Hormone receptor positive, HER2neu negative breast cancer is the most common disease type among all women, but its prevalence is highest among NHW women. Hispanic and API women have the lowest rates of this type of breast cancer. Hormone receptor and HER2neu negative disease is most common in the NHB population—twice as high as that of NHW women. Looking at API women with hormone receptor negative and HER2neu positive disease, Korean, Filipina, Chinese and Southeast Asian women have a higher risk for this breast cancer subtype compared to Japanese and AI women.
There were differences in breast cancer presentation. NHW and API women present most frequently with localized disease (breast alone), while NHB and Hispanic women have higher rates of presenting with regional (breast and axillary nodes) disease. NHB women have the highest rates of presenting with metastatic disease.
The group also looked at breast cancer mortality. Rates of death have decreased by 39% through 2015, which translates to over 322,000 lives saved. Interestingly, the decline among AI/AN women began 10 years later than for other ethnic groups. This decline in the death rate is due to improved cancer treatment as well as screening mammography. Although rates of death have dropped for all women, this improved survival is not equivalent among ethnic groups. NHB women still have a 39% greater breast cancer mortality compared to NHW women. While such differences may be due to different breast cancer types and prognoses, there is evidence that healthcare access continues to play a role in determining breast cancer outcomes: the survival rates were almost equivalent between these groups in Delaware, Connecticut and Massachusetts, states who have succeeded in providing equitable healthcare for many of their residents.
This information enlightens us with the most recent data about breast cancer in the US. Breast cancer subtypes among different ethnicities may reflect inherited and/or environmental differences. Socioeconomic and lifestyle differences, as well as cultural traditions, clearly play significant roles in breast cancer detection, treatment and outcomes. All of these factors complicate the interpretation of trends but provide more avenues for exploration to improve breast cancer outcomes for all women.