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Annual Screening Mammography for Women in Their Forties?

Mammography is less sensitive in younger than older women, but yearly screening can improve detection rates.

Whether, and how often, women in their forties should undergo mammographic screening remains controversial, as mammography is less sensitive in this age group than in older women. These investigators sought to identify factors associated with reduced mammographic sensitivity in younger women. First, they examined rates of interval cancer (defined as cancer diagnosed within 2 years after a negative screening mammogram) in 73 women in their forties and 503 older women with invasive breast cancer. They then compared mammographic and tumor characteristics between the younger and older women.

Younger women had significantly higher rates of interval cancer (i.e., reduced mammographic sensitivity) than did older women, both within 1 year (28% vs. 14%) and 2 years (52% vs. 25%) after mammography. Regardless of age, factors strongly associated with diagnosis of interval tumors included premenopausal status, mammographically dense breast tissue, and histopathology/immunocytochemistry characteristics predictive of rapid tumor growth. Mammographic-quality parameters most associated with interval cancers were noise and positioning errors. Greater breast density in younger women explained about two thirds of their excess risk for interval cancer within 1 year; greater breast density and more rapid tumor growth explained most of their excess risk within 2 years.

Comment: The incidence of breast cancer is substantially lower in younger than in older women. Nonetheless, mammographic breast density is greater and tumors grow more rapidly in women younger than 50, and this report documents that these factors contribute to the lower mammographic sensitivity in this age group. The authors note that yearly mammography can raise sensitivity in younger women; indeed, in this study, mammography was 48% sensitive for the 2-year follow-up, but was 72% sensitive when follow-up was limited to 1 year. The data underscore the importance of continued efforts to improve imaging in young women with dense breast tissue, including enhancing conventional mammography and using alternative and newer technology (e.g., magnetic resonance imaging). Finally, this report reminds us that determining the optimal screening frequency in younger women merits ongoing attention.

— Andrew M. Kaunitz, MD

Published in Journal Watch Women's Health December 8, 2004

Citation(s):

Buist DSM et al. Factors contributing to mammography failure in women aged 40-49 years. J Natl Cancer Inst 2004 Oct 6; 96:1432-40.

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