Annual Mammograms in Women Over 40 Detect Earlier, Smaller Breast Cancers

Laurie Barclay, MD

July 28, 2003

July 28, 2003 — Women older than 40 years who have annual screening mammograms are more likely to be diagnosed with ductal carcinoma in situ (DCIS) and/or smaller tumors compared with women screened less frequently, according to the results of a study published in the September 1 issue of Cancer and published online July 28. In addition, they were more likely to be offered breast conservation therapy.

"This study confirms a significant downstaging of tumor stage and tumor size associated with mammography screening [for women older than 40 years] that has been shown in other recent studies as well," write Gary M. Freedman, MD, from Fox Chase Cancer Center in Philadelphia, Pennsylvania, and colleagues.

Although routine screening mammography for breast cancer has been shown to have significant benefit in detecting early breast cancer, especially in women older than 50 years with less dense breast tissue, evidence for benefit has been less clear in women between the ages of 40 and 49 years.

Of 1,591 women aged 40 years or older and treated for breast cancer between 1995 and 2001, 192 had no previous mammography, 695 had mammography less often than annually, and 704 had mammography at least once a year.

Difference in tumor stage was statistically significant between these three groups (P < .0001). DCIS was diagnosed in 26% of women screened annually, in 21% of women screened less often, and in 15% of women without prior screening. Stage T1 tumors (<2 cm) were diagnosed in 56% of patients screened annually, in 50% of patients screened less often, and in 32% of patients with no previous mammogram. Tumor size was not greater than 1 cm in 20% to 23% of patients with annual or less frequent screening and in 8% of women with no history of mammography.

In the groups with annual or less frequent mammograms, 61% of women were offered the option of breast conservation therapy, compared with 41% in the group with no prior mammography. Mastectomy was recommended to 41% of women with no history of mammography and to 28% in the remaining groups. Outcomes data were not available. These trends were similar in the subgroup of women aged 40 to 49 years.

"This study supports many of the benefits associated with mammographic screening for women 40 years or older and supports at least a yearly interval versus more than yearly for optimal detection of the most curable forms of breast cancer," the authors write.

Cancer. 2003;98:000-000

Reviewed by Gary D. Vogin, MD


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