Screening Mammography in Older Women
Abstract & Commentary
Synopsis: Regular screening mammography up to and even past 85 years of age was found to reduce mortality by detecting breast cancer at its earliest stages.
Source: McCarthy EP, et al. J Am Geriatr Soc. 2000;48:
1226-1233.
Two sources of data were combined for a large sample of women 67 years of age and older to match their use of mammography with diagnosis of a first primary breast cancer and subsequent mortality. The National Cancer Institute and the Health Care Financing Administration have developed a linkage between Medicare physician claims which record mammography use, and the national breast cancer registry for Surveillance, Epidemiology and End Results (SEER). By analyzing a 7-year period from 1987-1993, McCarthy and associates were able to track a study sample of 11,399 women in 3 geographically separate areas who received a new diagnosis of first primary breast cancer. They were also able to obtain demographic and ethnic information from the Medicare beneficiary enrollment files.
Regular mammography use declined with advancing age at diagnosis: only 10% of women age 85 and older had regular mammograms, compared to 23% of women age 75-84 and 29% of women age 67-74. Regular use was defined as at least 2 mammograms in the 2 years preceding their breast cancer diagnosis, at least 10 or more months apart. Later stage breast cancer was generally detected in the oldest women: 53% of women age 85 and older had stage II or greater compared to 41% and 45% for the younger age groups.
When stage of diagnosis was matched with use of mammography, it was clear that regular users of mammography were significantly more likely to be diagnosed with early stage breast cancer compared to non-users. Only 28% of regular mammography users of all ages presented with late-stage disease. If women did not use regular mammography, the late-stage disease increased with advancing age, from 49% for age 67-74 up to 69% for age 85 and older. Even after adjusting for factors known to be associated with late-stage diagnosis, such as race, comorbid conditions, and income of zip code of residence, the lack of mammography remained a significant predictor of late-stage diagnosis within all age groups.
Survival also decreased with later stage of diagnosis, and decreased even further with advancing age within each cancer stage. After adjusting for comorbidity and sociodemographic factors, nonusers of mammography had a significantly greater risk of death from breast cancer within each age group.
COMMENT BY MARY ELINA FERRIS, MD
Breast cancer remains the second leading killer of women from cancer (lung cancer being the first), and accounts for the largest number of new cancer cases in women other than skin cancer. The risk of breast cancer for older women rises with age, but it’s long been a quandry in geriatric medicine whether to continue annual screening mammography in women older than age 70 when many guidelines stop further recommendations. Although the American Cancer Society and the National Cancer Institute recommend indefinite annual or biennial screening, other organizations such as the American Academy of Family Physicians recommend stopping at age 69, and the NCQA HEDIS® quality indicators for managed care health plans measure regular mammography only up to age 69. The American College of Physicians recommends mammography screening until age 74 years, based on the oldest ages of clinical trial participants. The U.S. Preventive Services Task Force analysis of the scientific evidence behind these recommendations has stated that there is limited and conflicting evidence for use in ages 70-74, and little research for use in age 75 and older.1
This new article provides strong support for continuing screening mammography for older women of any age as long as they would benefit from the early detection of breast cancer. Both the breast cancer stage at diagnosis and mortality were better for women who were regular users of mammography, especially at advanced ages. Combined with another recent article that also confirmed increased life expectancy for women using mammography during ages 70-79,2 this will probably be the best evidence we can hope for in lieu of randomized controlled trials.
New recommendations from the American Geriatrics Society urge us to continue annual or at least biennial mammography until age 75 and subsequently every 2-3 years thereafter with no upper age limit as long as women have an estimated life expectancy of at least 4 or more years.3 While it will still remain an individual decision between the clinician and the older woman whether to continue screening mammography, there is now much better scientific support to continue mammography well into the oldest years.
References
1. US Preventive Services Task Force. Guide to Clinical Preventive Services: Report of the U.S. Preventive Services Task Force. 2nd ed. Baltimore, Md: Williams & Wilkins; 1996.
2. Kerlikowske K, et al. JAMA. 1999;282:2156-2163.
3. AGS Clinical Practice Committee. J Am Geriatr Soc. 2000;48:842-844.
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