Both black and white women age 75 to 84 years who underwent annual mammography had lower 10-year breast cancer mortality than corresponding women who underwent biennial or no/irregular mammographies. These findings were published in the American Journal of Medicine (doi:10.1016/j.amjmed.2015.06.032).
Breast cancer is the second most common cancer in women after skin cancer and was diagnosed in 230 000 women in the United States in 2015. Breast cancer afflicts 1 in 8 women in their lifetime and 1 in 25 die from the disease. Although a number of randomized trials demonstrate the benefits of mammography screening in women up to age 74 years, data are sparse in women older than 74 years, especially minorities. In 2010, 41% of breast cancer deaths were among the more than 19 million women age 65 to 84 years.
Among elderly women, the American Cancer Society and the United States Preventive Services Task Force recommend regular mammography from 65 to 74 years.
For this study, Charles H. Hennekens, MD, of Florida Atlanta University in Boca Raton, and senior author of the study, and his collaborators from Baylor College of Medicine and Meharry Medical College used Surveillance, Epidemiology, and End Results (SEER) data linked to Medicare administrative claims to identify screening mammography use from 1995 to 2009 of 64 384 non-Hispanic women (4886 black and 59 498 white).
The files, linked between claims and mammography use, permitted the researchers to explore breast cancer mortality differences between elderly black and elderly white women who self-selected for regular annual or biennial mammography screening. The researchers selected 69 years as the lower age limit because Medicare coverage of the general population begins at age 65 years. The exposure of interest was regular mammography screening in the 4 years immediately preceding a breast cancer diagnosis.
Three mutually exclusive categories were defined: no or irregular mammography; biennial mammography; and annual mammography. The researchers looked at data from non-Hispanic, white, or black women; Hispanics were not included because Hispanic white women have substantially lower mortality than non-Hispanic whites, and the number of Hispanic blacks is small. They also measured socioeconomic status looking at median household income, the percentage of persons living below the poverty level, and whether or not they had a high school education.
The study findings showed that white women who had died tended to be older, have later-stage disease at diagnosis, received chemotherapy, and were of a higher socioeconomic status. White women who died were less likely to have undergone surgery or radiation therapy. Similar characteristics were seen in black women as in white women.
Risk of disease-specific mortality at 5 years or 10 years was consistently lower in those women age 69 to 84 years who underwent regular annual screening mammography during the 4 years immediately preceding their breast cancer diagnosis compared with women who underwent no or irregular screening, regardless of race. The 10-year risks were more than 3 times higher among white and more than 2 times higher among blacks age 69 to 84 years with no or irregular screening compared with those who underwent annual screening.