Shorter mammography interval may improve breast cancer prognosis

Mammographic screening at intervals <1.5 years as recommended by the American Cancer Society-rather than every 2 years as recommended by the U.S. Preventive Services Task Force (USPSTF)-may improve breast cancer prognosis. So say the results of a retrospective study presented on Friday, December 6 at the annual meeting of the Radiological Society of North America (RSNA).

Researchers from Northwestern University/Feinberg School of Medicine in Chicago, Ill reviewed records of 332 women with breast cancer identified by screening mammography from 2007 to 2010. The participants were divided into three groups, based on length of time between screening mammograms: <1.5 years (207), 1.5 to 3 years (73), and >3 years (52).

No significant difference was seen between the groups in age, breast density, high-risk status, family history, or index histology. The % stage 0 or 1 cancer and % minimal cancer also did not differ between the groups (P=0.057 and P=0.165, respectively) nor did the size of invasive cancers (ANOVA, P=0.165).

Lymph node positivity, however, was lowest in group 1 (<1.5-year interval) and statistically significantly different from the other two groups (8.7% vs 20.5% and 15.4%; P=0.002). The study authors therefore concluded that screening mammography performed at a shorter interval than the 2 years recommended by the USPSTF significantly reduces the rate of lymph node positivity, and hence, improves patient prognosis.

“Our study looks at what would happen if the revised guidelines issued by USPSTF were followed by women,” said lead author Lilian Wang, MD. “We should be following the guidelines of the American Cancer Society and other organizations, recommending that women undergo annual screening mammography beginning at age 40.”  

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