Older women may benefit from undergoing screening mammography once every 2 years rather than once a year, indicate the findings of a large, long-term study.
Uncertainty exists regarding the appropriate use of screening mammography among older women because comorbid illnesses may diminish the benefit of such testing, noted the investigative team led by Dejana Braithwaite, PhD, an assistant professor of epidemiology and biostatistics at the University of California–San Francisco, in Journal of the National Cancer Institute. In order to examine the risk of adverse tumor characteristics and false-positive rates according to screening interval, age, and comorbidity, the group prospectively collected data on 2,993 women with breast cancer and 137,949 women without the disease who underwent mammography from 1999 through 2006. All the women were aged 66 to 89 years.
Nearly half (48%) of the women aged 66 to 74 years who underwent annual screening mammography had false-positive results, compared with 29% of women in the same age range who were screened every 2 years. Rates of late-stage breast cancer were similar between the annual and biennial groups, and no statistically significant differences in adverse tumor characteristics existed between the two groups in terms of comorbidity, age, or screening interval.
Braithwaite and colleagues concluded that among women aged 66 to 89 years, risk for advanced-stage breast cancer is similar for those who undergo biennial screening mammography and for those who are tested annually, and that biennial patients have lower cumulative risk of a false-positive finding.